Tape management
These options are effective when the backup destination is a tape device.
Enable file recovery from disk backups stored on tapes
The preset is: Disabled.
If this check box is selected, at each backup, the software creates supplementary files on a hard disk of the machine where the tape device is attached. File recovery from disk backups is possible as long as these supplementary files are intact.
The supplementary files' locations are as follows:
- In Windows XP and Server 2003: %ALLUSERSPROFILE%\Application Data\Acronis\BackupAndRecovery\TapeLocation.
- In Windows 7 and later versions of Windows: %PROGRAMDATA%\Acronis\BackupAndRecovery\TapeLocation.
- In Linux: /var/lib/Acronis/BackupAndRecovery/TapeLocation.
The space occupied by these supplementary files depends on the number of files in the respective backup. For a full backup of a disk containing approximately 20,000 files (the typical workstation disk backup), the supplementary files occupy around 150 MB. A full backup of a server containing 250,000 files may produce around 700 MB of supplementary files. So if you are certain that you will not need to recover individual files, you can leave the check box cleared to save the disk space.
Move a tape back to the slot after each successful backup of each machine
The preset is: Enabled.
If you disable this option, a tape will remain in the drive after an operation using the tape is completed. Otherwise, the software will move the tape back to the slot where it was before the operation. If, according to the protection plan, other operations follow the backup (such as the backup validation or replication to another location), the tape will be moved back to the slot after completion of these operations.
If both this option and the Eject tapes after each successful backup of each machine option are enabled, the tape will be ejected.
Eject tapes after each successful backup of each machine
The preset is: Disabled.
When this check box is selected, the software will eject tapes after any successful backup of each machine. If, according to the protection plan, other operations follow the backup (such as the backup validation or replication to another location), the tapes will be ejected after completion of these operations.
Overwrite a tape in the stand-alone tape drive when creating a full backup
The preset is: Disabled.
The option applies only to stand-alone tape drives. When this option is enabled, a tape inserted into a drive will be overwritten every time a full backup is created.
Use the following tape devices and drives
This option enables you to specify tape devices and tape drives to be used by the protection plan.
A tape pool contains tapes from all tape devices attached to a machine, be it a storage node or a machine where a protection agent is installed, or both. When you select a tape pool as a backup location, you indirectly select the machine to which the tape device(s) are attached. By default, backups can be written to tapes through any tape drive on any tape device attached to that machine. If some of the devices or drives are missing or not operational, the protection plan will use those that are available.
You can click Only selected devices and drives, and then choose tape devices and drives from the list. By selecting an entire device, you select all of its drives. This means that any of these drives can be used by the protection plan. If the selected device or drive is missing or is not operational, and no other devices are selected, the backup will fail.
By using this option, you can control backups performed by multiple agents to a large tape library with multiple drives. For example, a backup of a large file server or file share may not start if multiple agents back up their machines during the same backup window, because the agents occupy all of the drives. If you allow the agents to use, say, drives 2 and 3, drive 1 becomes reserved for the agent that backs up the share.
Multistreaming
The preset is: Disabled.
Multistreaming allows you to split the data from one agent into multiple streams, and then write those streams to different tapes simultaneously. This results in quicker backups and is particularly useful when the agent has higher throughput than the tape drive.
The Multistreaming check box is only available when you select more than one tape drive under the Only selected devices and drives option. The number of selected drives is equal to the number of simultaneous streams from an agent. If any selected drive is not available when a backup starts, this backup will fail.
To recover a multistreamed or both multistreamed and multiplexed backup, you need at least the same number of drives that were used to create this backup.
You cannot change the multistreaming settings of an existing protection plan. To use different settings or to change the selected tape drives, create a new protection plan.
Multistreaming is available both for locally attached tape drives and tape drives that are attached to a storage node.
Multiplexing
The preset is: Disabled.
Multiplexing allows you to write data streams from multiple agents to a single tape. This results in better utilization of fast tape drives. By default, the multiplexing factor—that is, the number of agents that send data to a single tape—is set to two. You can increase it up to ten.
Multiplexing is useful for large environments with many backup operations. It does not improve the performance of a single backup.
To achieve the fastest backup in a large environment, you need to analyze the throughput of your agents, network, and tape drives. Then, set the multiplexing factor accordingly, without over multiplexing. For example, if your agents provide data at 70 Mbit/s, your tape drive writes at 250 Mbit/s, and there are no bottlenecks in you network, set the multiplexing factor to three. A multiplexing factor of four will lead to over multiplexing and decreased backup performance. Usually, the multiplexing factor is between two and five.
Because of their structure, multiplexed backups are slower to recover. The bigger the multiplexing factor, the slower the recovery. Simultaneous recovery of multiple backups written to a single multiplexed tape is not supported.
You can select one or more specific tape drives for multiplexing, or use the multiplexing option with any available tape drive. Multiplexing is not available for locally attached tape drives.
You cannot change the multiplexing settings of an existing protection plan. To use different settings, create a new protection plan.
In a protection plan, the following combinations of multistreaming and multiplexing are possible:
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Both the multistreaming and multiplexing options are cleared.
Every agent sends data to a single tape drive.
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Only the multistreaming option is selected.
Every agent sends data to at least two tape drives simultaneously.
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Only the multiplexing option is selected.
Every agent sends data to a tape drive that accepts streams from multiple agents simultaneously. The maximum number of streams that a tape drive can accept is set in the protection plan and cannot be changed on the fly.
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Both the multistreaming and multiplexing options are selected.
Every agent sends data to at least two tape drives that accept streams from multiple agents simultaneously.
A tape drive can write only one type of backup at a time—either multiplexed or not multiplexed, depending on which protection plan started first.
Use tape sets within the tape pool selected for backup
The preset is: Disabled.
Tapes within one pool can be grouped into so-called tape sets.
If you leave this option disabled, data will be backed up on all tapes belonging to a pool. If the option is enabled, you can separate backups according to the predefined or custom rules.
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Use a separate tape set for each (choose a rule: Backup type, Device type, Device name, Day in month, Day of week, Month of year, Year, Date)
If this variant is selected, you can organize tape sets according to a predefined rule. For example, you can have separate tape sets for each day of the week or store backups of each machine on a separate tape set.
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Specify a custom rule for tape sets
If this variant is selected, specify your own rule to organize tape sets. The rule can contain the following variables:
| Variable syntax | Variable description | Available values |
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Backups of each machine will be stored on a separate tape set. | Names of the machines registered on the management server. |
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Full, incremental, and differential backups will be stored on separate tape sets. |
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Backups of machines of each type will be stored on a separate tape set. |
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Backups created on each day of the month will be stored on a separate tape set. |
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Backups created on each day of the week will be stored on a separate tape set. |
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Backups created during each month of the year will be stored on a separate tape set. |
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Backups created during each year will be stored on a separate tape set. |
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- For example, if you specify the rule as
[Resource Name]-[Backup Type], you will have a separate tape set for each full, incremental, and differential backup of each machine to which the protection plan is applied.
You can also specify tape sets for individual tapes. In this case, the software will first write backups on tapes whose tape set value coincides with the value of the expression specified in the protection plan. Then, if necessary, other tapes from the same pool will be taken. After that, if the pool is replenishable, tapes from the Free tapes pool will be used.
For example, if you specify tape set Monday for Tape 1, Tuesday for Tape 2, etc. and specify [Weekday] in the backup options, the corresponding tape will be used on the respective day of the week.