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User configuration 

Overview 

An administrator can change user account properties, Protected Item, Storage Vault, Device, and Policy settings via the Comet Server web interface.

A user can change their own Protected Item and Storage Vault settings via the Comet Backup client application interface.

The descriptions in this section apply to both situations.

Profile 

Username 

Usernames must be at least six characters long, using only the characters a-z, A-Z, 0-9, underscore (_), period (.), at (@), and hyphen (-).

Usernames are case-sensitive.

Changes to username support 

Prior to Comet 17.9.0, the characters @ and . were unsupported.

Certain versions of Comet expanded the list of characters allowed in usernames. Usernames that are valid for newer versions of Comet may be invalid when used with older versions of Comet. This may impact certain scenarios including software downgrades and/or mixed-server-version replication.

If you have usernames that would be invalid under older versions of Comet, please take care to ensure that all your Comet infrastructure is upgraded past the point of conversion, to prevent any potential issues that may occur.

Future versions of Comet may allow characters from international alphabets in usernames (subject to Unicode normalization).

Password 

Passwords must be at least eight characters long.

The password must be on one line (no CR/LF bytes are permitted).

Any other characters are permitted, including spaces, special characters, symbols, and characters from international alphabets.

Language 

The user is able to set their own language.

As of Comet 18.6.0, the following languages are supported:

Language Code First introduced
English en_US
Spanish es_ES Comet Beta 1.0.0
Brazilian Portuguese pt_BR Comet 17.3.2
Dutch nl_NL Comet 17.3.4
Italian it_IT Comet 17.9.0
German de_DE Comet 17.9.2
French fr_FR Comet 17.9.2
Croatian hr_HR Comet 17.12.6
Russian ru_RU Comet 18.5.0
Hebrew he_IL Comet 18.6.0

Help translate Comet 

Our company is committed to making Comet available in multiple languages. Our staff mostly only speak English, so we contract translation companies to perform this work. However, the best-quality translations come from our customers, who better understand the software and the backup industry.

If you want to correct a translation in Comet, or if you want to translate Comet into a new language, please see the help-translate-comet directory inside your Comet Server install folder for more information.

Timezone 

Comet uses universal time; when you log in to the web interface, times will be converted on display to your browser's timezone (which is inherited from your operating system timezone).

The Comet Backup client app resets the user's timezone automatically, to match the user's operating system timezone. An administrator can set the timezone to any valid IANA tzdata timezone. The default timezone for new accounts is always Etc/UTC.

Email addresses 

Comet Server has some built-in features to send email reports to customers. You can configure any number of email addresses for a user account.

Email addresses can be configured via Comet Server (as of 17.6.1) and via the Comet Backup client (as of 17.9.6). An administrator can set an account policy to control whether users are allowed to modify their own email addresses.

Quota 

Comet Backup supports Quota restrictions based on different types of data measurements.

All Protected Items Quota 

You can set a limit on the maximum size of all Protected Items in the user's account. When a backup job is performed, the total size of Protected Items is checked against this quota, and the backup job will be aborted if it would exceed quota. If possible, the quota limits are checked before starting the backup, to avoid inconvenient interruptions and wasted bandwidth.

Device Limit 

You can set a limit on the number of devices that may be registered into the user's account. If a user tries to log in to this account using a new device, the registration will fail with an error message.

Storage Vault quota 

For more information about Storage Vault quota, please see the Storage Vault > Quota section below.

Suspending Accounts 

This feature is available in Comet 17.8.0 and newer.

An administrator is able to suspend user accounts in Comet Server. An administrator can suspend a user account by clicking the 'Actions' button and choosing the 'Suspend' option. You can unsuspend a suspended account in the same way.

A suspended user cannot log in to the Comet Backup client and cannot backup nor restore any data. A user is not able to un-suspend themselves.

Protected Items 

Overview tab 

In the "Description" field, enter a brief name describing what data is being backed up. Select which type of data is to be protected.

"Files and Folders" items 

The "Files and Folders" option lets you back up files and folders on the PC.

Use the Plus button to browse files and folders for backup. You can also drag-and-drop files and folders into the Comet Backup client to select them.

The "Choose files" dialog displays a live estimate of the selected filesize (before compression and deduplication).

Filesystem snapshots 

On Windows, the "Take filesystem snapshot" option creates a VSS snapshot.

This enables Comet to back up files that are currently in-use. It also provides disk-wide "crash-consistency", as all files for backup will originate from the precisely same timestamp.

Non-Windows platforms do not currently require the use of this feature to back up in-use files, however, they also do not benefit from the disk-wide consistency.

This feature was enabled by default for new Protected Items in Comet 18.6.6.

Network shares 

Comet supports backing up Windows network shares (SMB / CIFS). However, you should prefer to install Comet Backup directly on the network device; this will offer increased backup performance.

On Windows,

  • The "Choose Items" dialog lets you browse through mapped network drive letters. You can also use the "Options > Browse UNC Path" option to directly browse a UNC path.
  • Comet 18.6.5 and later support entering custom Windows Network Authentication credentials via the "Log in to network share" option. If you select a network share for backup, you may need to enter custom credentials in order for the service user account to access the network share.
  • Because mapped network drives are private to a user session, Comet Backup automatically converts mapped network drive letters into their UNC path equivalent, so that it can still be accessed by the service user account.

On non-Windows platforms,

  • You should mount the network share locally before backing it up.

Encrypted files (Windows EFS) 

Comet 18.6.7 supports backing up EFS-encrypted files on Windows. The files will be silently decrypted if possible (e.g. if Comet Backup is running as the encryption user, or if Comet Backup is running as the EFS Recovery Agent user).

If it is not possible to automatically decrypt the file for backup, Comet will back up the file in its encrypted form, and will only be able to restore it in its encrypted form. EFS-encrypted files are displayed with green text in the Restore browser dialog in Comet Backup.

If you have a PC failure, the EFS encryption keys may be lost. In this situation, the EFS-encrypted files may be unusable, even after restoring from backup. Comet warns you about this situation by adding a warning message in the backup job log.

In order to safely prepare for this scenario, you should export the PC's EFS encryption keys, so that the files can be accessed after a PC failure. On Windows, you can do this via certmgr.msc; or on Windows Server, taking a System State backup may be sufficient.

Once you have safely backed up the PC's EFS encryption keys, you can suppress the warning in Comet Backup by enabling the "I confirm EFS keys are exported" option.

Windows Server Deduplication 

This section applies to Comet 18.5.3 and later.

Windows Server 2012 and later have a data deduplication feature that is separate- and unrelated- to Comet's own deduplication, that can be used to increase free disk space on NTFS volumes. A scanning process runs in the background to find and merge duplicate file content. By default, the scanning process runs overnight.

Deduplicated files look and behave like normal files; however, they are stored on disk in a special format, that can only be read by Windows Server (and Linux). Non-Server versions of Windows are entirely unable to read these files from disk.

When backing up deduplicated files with Comet, it backs up the full (rehydrated) file content, and then applies its own deduplication to it. This means that Windows Server deduplicated files can be safely restored to non-Server versions of Windows.

When restoring deduplicated files from Comet, the files are restored in their full (rehydrated) format, and are not re-deduplicated until Windows runs its next background scanning pass. This means that you may not have enough free disk space to completely restore a Comet backup to the same source drive.

Exclude filters 

You can exclude a range of files from the backup job. An exclusion filter checks whether to exclude each file from backup, using either a glob pattern or a regular expression (regex).

There is no limit to the number of exclusion filters you can add to a single Protected Item.

Glob pattern match 

Comet can exclude files based on a glob pattern. Any files matching the glob pattern will be excluded from the backup job.

The expression is tested against the full disk path to the file. Your glob expression can be a partial match (e.g. *.txt) or a fully anchored match (e.g. C:\path\to\file.docx).

Some special characters and wildcards are allowed:

  • A star (*) skips zero or more characters within a filename
  • A double-star (/**/) skips any number of directory components
  • A question-mark (?) skips a single character within a filename
  • Square brackets denote a character class (e.g. [0-9]) within a directory or file name

As of Comet 18.9.1, an invalid glob pattern will prevent a backup job from running.

Regular expression match 

This feature is available in Comet 17.6.13 and later.

Comet can exclude files based on a regular expression (regex). Any files matching the regular expression will be excluded from the backup job. The specific syntax flavour is that of the Go regexp library.

The regular expression is tested against the full disk path to the file. This enables filtering by path component, or (on Windows) drive letter.

By default, the regular expression is

  • case-sensitive. You can perform a case-insensitive match by adding an (?i) expression
  • non-anchored. You can restrict your regex to the start- or end- of the file path by using the ^, $, \A and/or \z expressions.

Forwardslash (/) is not a special character and does not require escaping with \/.

An invalid regular expression will prevent a backup job from running.

System exclusions 

The Comet Backup system automatically excludes certain folders.

On Windows, Comet skips

  • The $RECYCLE.BIN and System Volume Information directories in any drive root
  • The C:\Recovery directory
  • The C:\pagefile.sys, C:\hiberfil.sys, and C:\swapfile.sys files (as of Comet 17.6.1)
  • Symbolic links on the C: volume that have both the hidden + system attributes (prior to Comet 18.6.4)
    • This is intended to work around an issue with application compatibility symbolic links (symlinks) used by the operating system.
    • Comet 18.6.4 and later back up these entries as symlinks.
  • The MicrosoftEdge.exe file (as of Comet 18.6.7)
    • This is intended to work around an issue with The file cannot be accessed by the system messages affecting Windows 1803 and later.
  • Invalid .DFSFolderLink files (as of Comet 18.6.6)

On other platforms, Comet skips

  • The /proc directory
  • The /sys and /selinux directories (as of Comet 17.8.1)

Rescan unchanged files 

This feature is available in Comet 17.3.0 and newer.

In a regular "Files and Folders" backup, Comet will skip over files that have the same file size and modification time as the last backup job. If these properties are the same, Comet will refer to previous chunks and not re-chunk the file. This dramatically improves performance.

If you are working with certain types of files that change content without updating their modification time attribute on the filesystem - for instance, applications that use direct disk I/O instead of filesystem functions; some database data files; or VeraCrypt container files - then the above is obviously unsatisfactory for ensuring backup integrity. In this case, you can enable the "Rescan unchanged files" feature to cause Comet to chunk every encountered file. This has some performance penalty but does ensure backup integrity in the presence of such files.

"Program Output" items 

The "Program Output" backup type backs up the stdout (Standard Output) stream of any command execution. This stream data is saved as a virtual file within the backup job. You can choose the virtual file name.

The data is streamed directly to the backup destination and never touches the local disk. This has the consequence that no progress bar or ETA can be calculated or displayed during backup jobs.

If the target application produces any content on stderr (Standard Error), it will be logged in the job report, and the final job status will not be less severe than "Warning".

If the target application exits with a non-zero error code, the error code will be logged in the job report, and the final job status will not be less severe than "Error".

"Microsoft Exchange Server" items 

Using this Protected Item type may incur a Booster charge.

This Protected Item type backs up Microsoft Exchange Server databases. The underlying technology is VSS and is compatible with Microsoft Exchange Server 2007 and later, including Exchange Server 2016 (the latest version at the time of writing).

The appropriate VSS writer must be installed.

As Exchange Server can only be installed on Server SKUs of Windows, this backup type is only applicable when running on Windows Server.

Some forms of Exchange Server backup will cause log truncation to occur on the Exchange Server. For more information, please see the official Exchange Server documentation. If circular logging is enabled on the Exchange Server, the 'Incremental' and 'Differential' backup types have limited effect.

Exchange Server 2010 and newer are supported since Comet 17.1.0 Beta. Comet 17.9.7 extended the support back to Exchange Server 2007.

"Microsoft Hyper-V" items 

Using this Protected Item type may incur a Booster charge.

This Protected Item type backs up Microsoft Hyper-V virtual machines. The underlying technology is VSS and is compatible with all versions of Hyper-V running on Windows Server, including Windows Server 2016 (the latest version at the time of writing).

This backup type is only applicable when running on Windows Server. Hyper-V on Windows Desktop is not supported by this Protected item type.

Comet integrates with the Hyper-V VSS writer to perform a Hyper-V backup snapshot, including support for in-VM quiescence on supported guest operating systems.

Backing up a Hyper-V virtual machine with Comet includes, but is not limited to:

  • its configuration file
  • all attached virtual drives
  • the contents of memory (if the machine was running)
  • the full tree of saved checkpoints

You can select individual virtual machines for backup, or choose "All virtual machines".

Consistency and guest additions 

The following information applies to all products that perform Hyper-V backup.

When backing up a guest VM, it's important to get a consistent state of the VM. There are some different ways this happens.

If the guest OS has all necessary Hyper-V integration services installed, then the host can request for the guest VM to take a VSS snapshot. The snapshot is then exposed to Hyper-V on the host for Comet to back up. It shouldn't interrupt the guest OS. The VM backup is application-consistent.

If the host OS is running Server 2012 R2 or newer, but there are no integration services inside the guest OS, then Hyper-V will take a checkpoint of the VM; Comet will back up the checkpoint; and then the checkpoint will be removed. This kind of checkpoint does not interrupt the guest OS. The VM backup is crash-consistent.

If the host OS is older than Server 2012 R2, and there are no integration services inside the guest OS, then the VM will be paused; Windows will take a VSS snapshot of Hyper-V's files in paused state; the VM will be resumed and Comet will back up from the VSS snapshot. It would cause a short interruption to the guest OS. The VM backup is crash-consistent.

Replica VM 

The following information applies to all products that perform Hyper-V backup.

If you are using Hyper-V replication, you can back up your virtual machines from either the primary or replica host.

A backup taken on the primary VM host is application-consistent (if possible), by quiescing a VSS snapshot inside the VM guest; or crash-consistent otherwise. However, a backup taken on the secondary VM host is only ever crash-consistent, because the replica VM is not running in order for guest integration services to take a VSS snapshot.

Current versions of Hyper-V do not allow backing up a VM that is currently replicating. If a VM is found to be currently replicating at the time of backup, Comet will retry the operation a few times. If you repeatedly see errors of the form The virtual machine '...' cannot start a backup operation because it is currently executing a conflicting operation. Try the backup again., and you are running backups from the replica VM host, you could consider

  • scheduling the backup job to run at a time when it's more likely that the VM replication is up-to-date; or
  • using Before / After commands in Comet to temporarily stop VM replication while the backup job is running.

For more information about backing up a replica VM, see https://blogs.technet.microsoft.com/virtualization/2014/04/24/backup-of-a-replica-vm/

Pass-through disks 

The following information applies to all products that perform Hyper-V backup.

Hyper-V supports passthrough disks, to attach a physical disk from the host directly into the guest VM. This unmounts it from the host OS.

Hyper-V itself does not support backing up passthrough disks (nor does it support replicating them). A Hyper-V backup of the guest machines can be taken from the host, but does not include any data from passthrough disks.

You can work around this issue by either

  • installing Comet Backup inside the guest VM, and backing up the extra data at a file level (this will use an extra Device license); or
  • changing your passthrough disks to be a real disk containing a large .vhd or .vhdx file. The "New Virtual Disk Wizard" in Hyper-V Manager has an option to convert an existing disk to a .vhd or .vhdx file.

For more information about backing up passthrough disks in Hyper-V, see https://blogs.technet.microsoft.com/virtualization/2009/03/03/working-around-the-pass-through-limitations-of-the-hyper-v-vss-writer/

Troubleshooting 

Error "The term Get-VM is not recognized" or Error "Please install 'Hyper-V Module for Windows Powershell'." 

The "Hyper-V Module for Windows PowerShell" must be installed to use this feature. You can install this module from Powershell or from Windows Server Manager.

You can install the module from Powershell by running Install-WindowsFeature -Name Hyper-V-PowerShell.

You can install the module from Windows Server Manager, in "Add Roles and Features", in "Features". For Server 2016, the feature checkbox is located under "Remote Server Administration Tools" > "Role Administration Tools" > "Hyper-V Management Tools" > "Hyper-V Module for Windows PowerShell".

"Microsoft SQL Server" items 

Using this Protected Item type may incur a Booster charge.

This Protected Item type backs up a Microsoft SQL Server database. The underlying technology is VDI and is compatible with SQL Server 2005 and later, including SQL Server 2016 (the latest version at the time of writing).

No data is spooled to the local disk. As per the "Program Output" type, no progress bar or ETA appears during a Microsoft SQL Server backup.

Databases are backed up one-at-a-time. If you require point-in-time consistency across multiple databases, please use the "Application-Aware Writer" option instead.

Connection details 

Connection details should be supplied before selecting databases. Comet will only connect to SQL Server running on the local machine. You must enter the instance name, or leave the field blank to use the default instance.

Address 

The address is always localhost, but Comet does not use TCP addresses or TCP ports to connect to SQL Server instances. Comet uses "Shared Memory" to connect to SQL Server instances.

Comet's use of "Shared Memory" connection does improves performance for some operations, at the expense of only working on the local machine; but Comet's use of VDI requires it to run against the local machine anyway.

If you encounter issues connecting to your SQL Server, you must ensure that "Shared Memory protocol" is enabled in SQL Server Configuration Manager.

To support SQL Server instances that require the use of TLS 1.2, Comet first tries to connect to your SQL Server using the MSOLEDBSQL provider. If this provider is not installed, you can download it from https://www.microsoft.com/en-us/download/details.aspx?id=56730 .

If the MSOLEDBSQL provider is not installed, Comet connects to SQL Server using the legacy SQLOLEDB provider, which is always available.

In Comet 18.9.4, 18.8.5, and earlier, Comet always used the SQLOLEDB provider.

Authentication 

Comet allows you to connect to SQL Server using either Windows authentication (running as the local Administrator) or native SQL Server authentication.

  • If you are using Windows Authentication, the connection occurs as the local Administrator.
    • You can assign the local Administrator user to have sysadmin rights within SQL Server.
  • If you are using SQL Server authentication, you must enter a valid username and password to connect to SQL Server.

Impersonation is not currently available for Windows authentication. Future versions of Comet will support impersonation for Windows authentication.

Multiple instances 

Comet supports backing up multiple instances from SQL Server. You can select an instance for backup, by entering the instance name in the "Instance Name" field. Leave this field blank to use the default instance.

Comet Backup 17.6.3 automatically lists available instances for selection in the drop-down menu.

A future version of Comet will make the instance dropdown list available for remote administration in Comet Server.

Backup mode 

By default, Comet opts to make a full database export from SQL Server, and then uses its own deduplication system to optimise the stored/uploaded data.

This is the "Full (copy only)" option. It is equivalent to the BACKUP WITH COPY_ONLY T-SQL statement.

Because Comet can efficiently deduplicate full image backups, it is normally sufficient to only take full backups of SQL Server in Comet.

Base images 

You have the option to use SQL Server's own differential/log backup system. This may be more efficient, but it does require additional administrative work, and complicates the process of restoring data.

The SQL Server maintains one single point-in-time reference, from which it can produce differential backups and/or log-based backups. When you take a new "Full (base image)" backup, the point-in-time reference is moved forward, so that any future differential and/or log-based backups are based on the last base-image backup.

To use SQL Server's own differential/log backup system, you must create multiple Protected Items (each with a different schedule) in order to capture both a base image and a differential/log backups. By creating multiple Protected Items, you can individually schedule, report-on, and manage retention policies for both base and differential/log backups.

If you are using Comet alongside another product for SQL server backups, you should ensure that only one product is taking base-image backups. Otherwise, it's possible that a chain of differential/log backups would be incomplete.

Prior to Comet 18.3.3, this option was labelled as "differential base image".

Differential 

Comet can use SQL Server's own systems for differential backup. In this mode, you can regularly make "differential base" backups, and then a series of small "differential increment" backups, each containing the difference from the last base backup. These operations are equivalent to the BACKUP and BACKUP WITH DIFFERENTIAL T-SQL statements respectively. Comet will still deduplicate multiple base backups that are sent to the same Storage Vault.

This is the "Differential increment" option.

Log 

You can opt to use SQL Server's own systems for log backup. In this mode, you must periodically take full (base image) backups, and regularly take log backups.

You have the choice of whether to apply log truncation. These operations are equivalent to the BACKUP LOG and BACKUP LOG WITH NO_TRUNCATE T-SQL statements respectively. Comet will still deduplicate all data that is sent to the same Storage Vault.

To use SQL Server's own log system, you must create multiple Protected Items (each with a different schedule) in order to capture both full and log backups.

This mode requires that the database Recovery Model is set to "Full" or "Bulk Logged" in SQL Server. For more information, please see https://msdn.microsoft.com/en-us/library/ms189275.aspx .

Recommendations 

In general, we would recommend using the default "Full" backup technique.

SQL Server's native differential/log systems may be used if you experience performance issues with the default mode, however, you must ensure that

  1. No other backup systems are resetting the last base backup;
  2. Whenever the differential/log backs up successfully, that the base has also recently backed up successfully;
  3. Base backups are performed regularly to minimise differential overhead; and
  4. Retention is carefully managed to ensure that recovery is possible

Alternative ways to back up Microsoft SQL Server 

You can use Comet's "Commands" feature to call osql/sqlcmd to run a T-SQL BACKUP statement against the database, and then back up the resulting spooled file with the "Files and Folders" type. This option requires more temporary disk space than the built-in system above.

You can use the "Application-Aware Writer" type to back up SQL Server using the VSS Writer. Compared to Comet's standard VDI approach, this option enables more detailed progress information, and can take a consistent point-in-time snapshot of multiple databases at once; but offers more limited control over SQL Server features such as log truncation. The resulting files also must be restored in a different way.

You can use the "Files and Folders" type to back up individual database files if the "Take filesystem snapshot" option is selected. However, the "Files and Folders" backup type does not invoke SQL Server's VSS writer, so this would (at best) produce a "crash-consistent" backup and is not recommended.

"MySQL" items 

This Protected Item type backs up a MySQL database. It is also compatible with MySQL-compatible servers such as MariaDB and Percona Server. It works at the logical (SQL) level.

No data is spooled to the local disk. As per the "Program Output" type, no progress bar or ETA appears during a MySQL backup.

Connection details 

Connection details should be supplied before selecting databases. Fill in the fields at the bottom of the dialog window.

Selecting databases 

Use the plus button on the right to open a database browser, allowing you to select individual databases for backup. Use the dropdown-plus button to add a custom property.

Custom mysqldump 

Comet Backup's MySQL support works at the logical (SQL) level using mysqldump.

The mysqldump binary is selected as follows:

  • If a custom path to mysqldump has been set, this binary is used.
  • Otherwise, if there is a version of mysqldump installed (e.g. you are backing up a MySQL server from the server itself), the local version of mysqldump will be used to ensure maximum compatibility.
  • Otherwise, if no copy of mysqldump can be found, the Windows version of Comet Backup bundles a recent mysqldump binary in compliance with its license.
  • If no suitable mysqldump binary is found, the MySQL backup job will fail. This failure can be detected via the backup job's status or its log entries.

"Windows Server System State" items 

Comet Backup integrates with Windows Server System State to support backing up System State .vhd files using the wbadmin technology. This feature is only available on certain versions of Windows Server with the "Server Backup Role" feature enabled.

A Windows Server System State backup may include Active Directory, boot files, the COM+ registration, the system Registry hive, and/or other system files.

A local path must be used for spooling temporary data. Spooled temporary data will be removed once the backup job completes. The selected path

  • must be a bare root drive, and
  • must support VSS, and
  • must have at minimum 10GB free space, and
  • must not reside on a "critical" volume (unless KB944350 has been applied).

For more information about Windows Server System State backups, please see

Restoring 

Once you restore the .vhd file with Comet, you can use the wbadmin start systemstaterecovery command to apply a System State .vhd backup to an installed copy of Windows Server.

Alternative ways of backing up System State 

Note that because wbadmin is used, spool space is required. As an alternative, you can back up System State by using the "Application-Aware Writer" Protected Item type. This produces a similar result, but

  • no spool space is required; and
  • the files are not collected in a .vhd file. This may produce better deduplication at the expense of missing bootloader files.

"Windows System Backup" items 

Comet Backup integrates with Windows System Backup to support backing up entire system volumes as .vhd files using the wbadmin technology.

Choose volumes to back up, and/or choose "all critical volumes".

A local path must be used for spooling temporary data. Spooled temporary data will be removed once the backup job completes. The selected path

  • must be a bare root drive, and
  • must not be included as one of the selected volumes.

Restoring (Data drive) 

Once you restore the .vhd file with Comet, it can be mounted in Windows to extract individual files, or it can be attached to a virtual machine, or written out to a physical volume.

Restoring (Operating System) 

Once you restore the .vhd file with Comet, you can boot into either Windows Recovery or the Windows install media, and choose the "System Image Recovery" option.

Alternatively, the .vhd file can be attached to a virtual machine or written out to a physical volume. Because the .vhd is a data-only file, you may need to manually recreate the NTLDR bootloader (using the bootsect and bcdedit commands) before the machine can be booted.

Note that the disk image is not pre-prepared for hardware independence. An operating system image may only mount on identical- or highly-similar hardware. This issue originates from the wbadmin "Windows System Backup" technology and is not specific to Comet's implementation. You may find more information online.

Alternative ways of backing up Windows System Backup 

Note that because wbadmin is used, spool space is required. It may be preferable to use the "Files and Folders" backup type instead, that does not require spool space.

"Application-Aware Writer" items 

Using this Protected Item type may incur a Booster charge.

About 

VSS is a technology for taking a consistent point-in-time snapshot of a disk volume. A VSS Writer is an extra software plugin that detects when this action is taking place and ensures that application-specific files are in a safe state on disk. Comet's "Application-Aware Writer" feature allows you to invoke a single VSS Writer, or a sub-component of a single VSS Writer, and back up only the files that it was protecting.

This is also an important third-party integration point for application vendors. If your third-party application includes a VSS Writer, you can use this Protected Item type to back it up using Comet.

Some products that can be backed up with this Protected Item type are:

  • Oracle DB;
  • MailStore Server;
  • Microsoft Dynamics CRM;
  • Microsoft Sharepoint;
  • Pervasive PSQL;
  • other products natively supported by Comet, including Microsoft Exchange Server, Microsoft Hyper-V, and Microsoft SQL Server;
  • and other products.

This feature was added in Comet 17.6.1. In versions of Comet before 18.3.13, the Protected Item type was named "VSS-Aware Component".

NOTE: This Protected Item type is intended for integration with specific custom applications. If you want to back up normal files with a VSS snapshot, use the "Files and Folders" Protected Item type with the "take filesystem snapshot" option enabled.

Selecting components 

In Comet Backup, click the Edit button (pencil icon) to browse the available VSS Writers installed on your device.

You can select the top-most checkbox to include all components within the VSS Writer, or you can select individual components within the VSS Writer. For instance, the Microsoft SQL Server VSS Writer allows you to select individual databases for backup.

The VSS Writer itself may mark some components as non-selectable. This is shown in Comet as a grey subcomponent without a checkbox.

VSS Mode 

You can perform the operation in "VSS Full", "VSS Copy", "VSS Incremental", or "VSS Differential" modes. If a specific VSS Writer does not support the selected backup mode, it will perform the backup in "Full" mode.

The actual behaviour of these modes is specific to each VSS Writer. For more information, consult the documentation for your VSS Writer.

Schedules 

Comet can run backup jobs automatically on a schedule. It is strongly recommended to automate your backups on a regular schedule.

Click the plus button to add a new schedule.

General Schedule options 

When a schedule is due to run, the backup job will run automatically to the selected Storage Vault.

You can also configure advanced backup runtime options:

  • Skip if already running. If this option is enabled, and another backup job is known by the Comet Server to exist for the same Protected Item and Storage Vault in "Running" status, then this backup job will be skipped. Skipping a backup job creates a log entry for the job in "Skipped" status.
  • Cancel if still running after. You can set a time limit for the backup job. If the backup job exceeds this time limit, the backup job would be cancelled.
  • Limit Storage Vault Speed. This option allows you to limit the total speed that Comet reads and writes to the Storage Vault. The speed limit applies to the total combined read/write bandwidth.
  • Limit backup to use only 1 disk thread. When reading multiple files from the local disk for backup, Comet Backup uses multithreading to improve performance. On some machines, this can impact PC performance. If you are experiencing low system performance while the backup job is running, you can try enabling this option to see if it resolves the issue.

Schedule times 

You can configure the times when this schedule will be executed. You can add multiple times to the same schedule.

The available time-based schedule frequencies are:

  • Hourly. The schedule would run every hour. You can choose the minutes past the hour.
  • Daily. The schedule would run every day. You can choose the time of day (hours/minutes). The hours are specified in 24-hour time, from 0 to 23.
  • Weekly. The schedule would run every week. You can choose the day of the week, and the time of day (hours/minutes). In Comet 18.6.1 and later, you can choose multiple days of the week.
  • Monthly. The schedule would run every month.
  • Once only. The schedule would run only when the specified date and time is reached.

If the device is online, Comet Backup will try to run the backup job. If the device is not online, or the backup job could not be started, the Comet Server will inject a "Missed" job into the customer's backup job log. Administrators can use these "Missed" backup job notifications when monitoring the job history for their customers, to ensure that backup jobs run on schedule.

As of Comet 18.6.7, event-based schedule frequencies are also available.

The available event-based schedule frequencies are:

  • Also run when PC starts. The schedule would be initiated immediately after the PC boots.
  • Also run when PC starts, if the last job was Missed. The schedule would be initiated immediately after the PC boots if the last backup job for this Protected Item and Storage Vault pair was in Missed status. This allows you to "catch up" missed backups for PCs that are only online at irregular intervals (e.g. laptops).

The time that the "PC starts" is defined as follows: the time that the Comet Backup background service started, if the system uptime is less than 10 minutes. (This definition is subject to change.)

Commands (Schedule) 

You can configure Commands that run before/after this Schedule runs.

The Commands feature on a Schedule works the same way as for Commands on a Protected Item or on a Storage Vault. For more information about the Commands feature, please see details under the Overview and Concepts section.

Commands (Protected Item) 

You can configure Commands that run before/after this Protected Item is backed up.

The Commands feature on a Protected Item works the same way as for Commands on a Storage Vault or on a Schedule. For more information about the Commands feature, please see details under the Overview and Concepts section.

Retention (Protected Item) 

On the Retention tab, you can configure a retention policy to apply when backing up this Protected Item to a specific Storage Vault. If no policy is configured for a specific Storage Vault, the default retention policy for the Storage Vault will apply.

Retention (Storage Vault) 

"Retention" is the concept of classifying backed-up data, to determine what data should be kept, and what data can be safely removed in order to free up disk space. For instance, you may choose to keep the last 30 days' of backed-up data, or all data from the last 100 backup jobs; but any data older than this is unlikely to be useful and can be safely removed.

Retention Pass 

After each backup job, a "retention pass" runs for the Storage Vault. You can also run a retention pass for a Storage Vault on demand, by right-clicking the Storage Vault within the Comet Backup application.

During a retention pass, Comet Backup looks at each backed-up job within the Storage Vault and determines whether it meets the retention policy. If the retention policy states that the backed-up job can be safely removed, the backed-up job is removed from the Storage Vault. Once all backed-up jobs are checked against the retention policy, any data chunks that are no longer referenced by a backed-up job can then be pruned to save disk space.

Preferences 

Comet allows you to configure retention for a Storage Vault, as well as for a Protected Item / Storage Vault pair.

The retention rule for the pair will be used in preference to the retention rule for the Storage Vault. The retention rule for the Storage Vault is therefore only applied when

  • there is no overridden retention rule for the Protected Item / Storage Vault pair; or
  • the Protected Item is unknown, deleted, or belongs to a different Comet user account

Retention policies 

In Comet 17.6.1 there are two categories of retention policy:

  • A policy that keeps all data forever, and
  • A policy that keeps data as long as it falls within any of a set of configurable ranges. You can combine multiple ranges to create a more complex policy.

Retention ranges 

A retention range is a time period or job count during which a backup job should be kept.

The following ranges are available:

"Last [...] backups" - Specify a number of backups to keep. If the backup job was within the last X backups, then the backup job will be kept.

"All backups in the last [...]" - Specify a number of days, weeks, and/or months. If the backup job occurred recently within the specified range, then the backup job will be kept.

"All backups newer than a specific date" - Specify a specific date. If the backup job occurred after that specific date, then the backup job will be kept.

Future versions of Comet may make additional Retention Range options available.

Storage Vaults 

General tab 

On this tab, you can give a name to the Storage Vault. You can use any name; if you have multiple Storage Vaults within an account, we would recommend using a name that identifies the content and/or purpose of the Storage Vault.

On this tab, you can also configure a retention policy for the Storage Vault.

Quota (Storage Vault) 

On this tab, an administrator using Comet Server can configure a quota limit, restricting the total amount of data stored within this Storage Vault.

You can set this property on a per-Storage Vault basis. For example, you could use this feature to limit the amount of data stored on an expensive network storage account, but still allow any amount of data to be stored on a local hard drive.

When a backup job is performed, the total size of the Storage Vault is measured and checked against this quota limit. As the job proceeds, the amount of uploaded data is compared against the remaining available size, and the backup job will be aborted once reaching this limit.

After a quota has been exceeded 

A backup job that is abandoned for reaching its Storage Vault quota does not remove the chunks that were uploaded to the Storage Vault. Future backup jobs will almost certainly fail immediately. In this situation, you have the choice between

  1. Raising the Storage Vault quota and retrying the backup. This will cause any existing chunks in the vault to be re-used, accelerating the backup quickly up to the point where it was interrupted; or
  2. Using the "Apply retention rules now" feature to clear unused chunks from the Storage Vault. This will reduce the data size within the Storage Vault and allow future backups to proceed.

Neither action is taken automatically - you should choose one action to take depending on the situation.

Storage tab 

On this tab, you can configure the data storage location for this Storage Vault. A number of types are available, including local disk storage, network accounts, and cloud storage providers. For more information about data storage locations, please see the Storage Configuration documentation.

Commands 

The Commands feature on a Protected Item works the same way as for Commands on a Storage Vault or on a Schedule. For more information about the Commands feature, please see details under the Overview and Concepts section.

Encryption 

Comet automatically enables encryption for all Storage Vaults. This is not customizable; this tab solely serves to indicate that fact to unaware users.

Storage Vault encryption is initialized upon first-use. You can use this tab to tell whether a Storage Vault has been initialized with an encryption key, and when the initialization was performed (according to records in the user account profile).

Devices 

You can log in to the same user account from multiple devices.

Each device in an account has their own private Protected Items, but shares the Storage Vaults. Because Storage Vaults are the unit of deduplication, all backups from all devices in the account can be deduplicated against each other. This also means that devices can restore each others' data.

An administrator can revoke devices from your account.

A device has a "friendly name" that is set by the device when it is first registered. The "friendly name" defaults to the hostname of the PC. An administrator can rename devices in an account.

Because additional devices may incur a cost, an administrator can also limit the total number of devices in an account.

If a device is live-connected to the Comet Server, an administrator can request that the device performs certain actions.

Policies 

An administrator can configure additional policy restrictions via the Comet Server web interface.

As of Comet 18.8.0, the available policy restrictions are:

  • Storage Vaults
    • Prevent creating new Storage Vaults (via Request)
    • Prevent creating new Storage Vaults (via Custom)
    • Prevent editing existing Storage Vaults
    • Prevent deleting Storage Vaults
    • Restrict available Storage Vault types
  • Protected Items
    • Prevent creating new Protected Items
    • Prevent editing Protected Items
    • Prevent deleting Protected Items
    • Restrict available Protected Item types
  • Default Settings
    • "Skip if already running" setting on backup schedules
      • Choose from System default; Optional, default on; Optional, default off; Always on; and Always off
  • Other
    • Prevent manually deleting backup snapshots from a Storage Vault
    • Prevent changing user account password
    • Prevent changing email settings
    • Prevent opening the application interface
      • Prevent devices from viewing each others' names
        • Device names will still be visible if the user logs in to the web interface.
      • Hide the Import feature
      • Hide the software version and codename
    • Prevent logging in to the web interface
  • Mandatory file and folder exclusions