The items that may be required for tape backup, and how to configure the items, are explained below:
Number of Tape Servers for load balancing
According to the number of transaction volumes on all Storage Servers, install multiple Tape Servers to distribute loads on the Tape Servers. Considering the general backup schedule, decide which Tape Servers should handle requests from which Storage Servers.
Make this setting according to "3.2 Association of Storage Servers with Tape Servers".
Backup destination media
Decide whether to back up data to both disks and tapes or to only tapes.
Consider whether a backup destination disk is available and how long transaction can be stopped for backup (a disk is required if transaction can only be stopped for a short time).
Configure this setting using the relevant option for "11.2.2.1 acmbackup (Backup command)".
To backup to both disk and tape, specify "BOTH" in the -m option.
To backup to only tape, specify "TAPE" in the -m option
After backup to only disk has been implemented, if you want to copy the backup data collected on disk to tape, specify "DISK" in the -m option.
Then execute "11.2.2.2 acmtphistcopy (Tape copy command)".
Do not use the swstbackup command for backup to only disk.
Point
The tape storage capacity depends on the type of tape. Refer to the following values to estimate the number of tapes required for backing up to tape:
LTO Generation 1 =~ 100GB
LTO Generation 2 =~ 200GB
LTO Generation 3 =~ 400GB
LTO Generation 4 =~ 800GB
Number of preservation generations
Determine the maximum generations of backup data to be saved. This will depend on how many backup destination disks and tapes can be reserved. For information on the number of preservation generations and the size of backup destination disks (backup volumes) required for it, refer to the "Operation Design" section of the Backup Operation chapter in the "ETERNUS SF AdvancedCopy Manager Operator's Guide" for the target Storage Server's operating system.
Set the number according to the "3.5.2.1 Tape backup management class" and "3.5 Backup Policy".
Number of preservation days
Decide how long the backup data saved to tape should be kept.
Set the number of preservation days using the "3.5.2.1 Tape backup management class". The number of preservation days cannot be set for disk data.
Number of concurrent backup tasks and the number of drives used.
In the operation mode in which multiple backup tasks are executed concurrently, the number of drives assigned to each Storage Server can be limited to prevent unbalanced allocation of drives.
When deciding upon the appropriate configuration, consider the entire backup schedule. For instance, when multiple Storage Servers execute backup concurrently, a certain Storage Server may first occupy all drives for executing backup. If so, the completion of backup by other Storage Servers may be delayed and this may adversely affect the start time of transaction. Limiting the number of drives each Storage Server can use concurrently can balance the drive allocation to Storage Servers and prevent this delay.
Limit the number of drives using the "3.3 Device Class". Create a storage pool that uses this device class and set the storage pool in the backup policy of the transaction volume.
Point
In tape backup, if the number of backup tasks executed concurrently exceeds the number of drives, backup tasks that were started later have to wait for idle drives. (The backup command does not return at this stage).
In this case, writing to tape starts automatically when the backup tasks that were started earlier are completed.
Snapshot or synchronous backup
Decide which type of disk backup is to be used, snapshot or synchronous.
For details of the snapshot backup and synchronous backup, see the "Overview" section in the Backup Operation chapter of the "ETERNUS SF AdvancedCopy Manager Operator's Guide" for the target Storage Server's operating system.
