| ETERNUS SF AdvancedCopy Manager Operator's Guide for Tape Backup Option 13.0 -Microsoft(R) Windows(R) 2000/Microsoft(R) Windows Sever(TM) 2003-, -Solaris-, -HP-UX-, -Linux-, -AIX- |
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This Chapter explains the design required for Tape Backup operation of AdvancedCopy Manager.
The items to be considered for carrying out tape backup and how to make settings for the items are explained below:
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 take care of requests from which Storage Servers.
Make this setting according to "Association of Storage Servers with Tape Servers".
Decide whether to back up data to both disks and tapes or to only tapes.
Decide this by considering whether a backup destination disk is available and how long transaction can be stopped for backup (a disk is required if the time during which transaction can be stopped is short).
Make this setting using an option of the "Backup command (acmbackup)".
Estimate the number of tapes required according to the size of the transaction volume and the number of preserve generations.
Register the number in "Storage Pool".
In 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.
Make decision in consideration of 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 such delay.
Limit the number of drives using the "Device Class". Create a storage pool that uses this device class and set the storage pool in the backup policy of the transaction volume.
In tape backup operation, if the number of backup and/or restoration tasks executed concurrently exceeds the number of drives, backup and/or restoration tasks that were started later are made to wait for idle drives. (The backup or restore command does not return at this stage.)
In this case, upon completion of the backup and/or restoration tasks that are started earlier, writing to tapes and/or reading from tapes automatically begin.
Determine the maximum generations of backup data to be saved. It depends 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, see "Operation Design" in each chapter about backup operation in the "ETERNUS SF AdvancedCopy Manager Operator's Guide" for the operating system of the target Storage Server.
Set the number according to the "Tape backup management class" and "Backup Policy".
Decide how long the backup data saved to tape should be kept.
Set the number of preservation days using the "Tape backup management class". The number of preservation days cannot be set for disk data.
Decide whether to simultaneously write the same backup data to multiple tapes. Make this setting in such cases as when backing up duplicate data to two different tapes and keeping one at a remote site in preparation for disasters. This setting cannot be made for disk data.
Make this setting in "Storage Pool".
Decide which type of disk backup is to be used, snapshot or synchronous.
For details of the snapshot backup and synchronous backup, see "Overview" in each chapter about backup operation the "ETERNUS SF AdvancedCopy Manager Operator's Guide" for the operating system of the target Storage Server.
Multiple Tape Servers can be installed. Installing the appropriate number of Tape Servers according to the number of transaction volumes on all Storage Servers can distribute loads on the Tape Servers.
The association of Storage Servers with Tape Servers defines which Tape Servers execute requests and from which Storage Servers the Tape Servers execute them.
Make this setting using the "Storage Server configuration information setting command (acmsvrset)".
Tape Backup of AdvancedCopy Manager uses TSM to manage tape library systems. TSM allows the user to set the way of using drives as a device class.
The following types of information can be set in the device class:
A storage pool is a logical area of backup destination tape. Tapes in a tape library system are grouped and managed as a pool. Tape Backup of AdvancedCopy Manager uses TSM to manage storage pools.
Allocating the backup destination to a storage pool can eliminate the need to recognize individual tapes for backup. Storage pools can be customized in various ways.
Tape operation using storage pools can be performed in two ways: private operation and scratch operation.
The tapes to be used need to be registered in advance in the storage pool. Backup is executed within the range of the tapes registered in the storage pool. The tapes once registered in the pool remain in the pool and reused as long as they are not removed intentionally.
The user need not register tapes in the storage pool. When needed, tapes are automatically registered and used for backup. When a tape is emptied after backup data on it is completely deleted, the tape is automatically removed from the storage pool.
The criteria for selecting the private operation and scratch operation are shown below:
Storage pools are classified into two: primary storage pools and copy storage pools. By defining one or more copy storage pools for a primary storage pool, backup data can be written simultaneously to both types of pools. When backup is executed, backup data is written to the primary storage pool and simultaneously kept in the related copy storage pool.
In this manual, the primary storage pool is represented as a "storage pool".
The backup policy specifies the management methods of backup destination storage pools and backup data.
A backup policy is defined for each transaction volume.
If disks are also used as backup media, the following variables must be set.
The number of preservation generation means how many generations of backup data should be preserved.
The snapshot high-speed backup first releases the least recent generation from the generation management. For this reason, if a fault such as a system failure occurs during backup operation, the required number of generations of backup data may not exist. To prevent this event, Fujitsu recommends reexecuting backup immediately.
If the snapshot high-speed backup operation is performed with 1 specified for the number of preservation generations, Fujitsu recommends using the operation mode in which backup data is saved additionally to tape.
The synchronous high-speed backup releases the least recent generation from the generation management after completion of backup of the latest generation. To keep complete history information, therefore, "number of preservation generations + 1" backup volumes are required.
Set the number of days between required backups.
If the number of days after the last backup is exceeded without a backup executed, a delay message is displayed.
Backup is not automatically executed regularly even if the number of days between backups is set.
Set the number using the "Disk backup policy setting command (acmbkpolset)".
Set a backup policy for using tapes. To do so, use a combination of a tape backup management class and tape backup policy.
The tape backup management class defines the operation rules for backup destination storage pools.
Define the following:
Name of the storage pool used to store backup data that is managed with the number of preservation generations specified.
Set the number of generations of backup data that should be preserved.
Set the name of the storage pool used to store backup data that is managed with the number of preservation days specified.
Set the number of days during which backup data should be preserved. Set the number using the "Tape backup management class setting command (acmtpmgmtclassset)".
Define the following:
Specify the name of the tape backup management class to be used.
Set the number of days between required backups.
If the number of days after the last backup is exceeded with no backup executed, a delay message is displayed.
Backup is not automatically executed regularly even if the number of days between backups is set.
Set the number using the "Tape backup policy setting command (acmtpbkpolset)".
This section summarizes the relationship between transaction volumes and policies, storage pools, device classes, and drives.
A policy is defined for each transaction volume. The policy defines an arbitrary storage pool to decide on the tapes to be used. In addition, a device class is defined for each storage pool. The device class defines the maximum number of drives that can be used concurrently.
In the following figure, seven transaction volumes and five drives are used. If backup is executed concurrently without defining the maximum number of drives that can be used concurrently, the backup operations by Server B may occupy four drives and Server A may be able to use only one drive.
If the maximum number of drives that can be used concurrently is defined as shown in the figure, Server A and Server B can use drives evenly. If the backup operations of all volumes are performed concurrently in this example, the backup operation for any one of the transaction volumes of each server is made to wait for an idle drive. When an idle drive becomes available, writing to tape begins.
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