8.5.1 Operating system mirroring

Logical volume mirroring (LVM) and Veritas Volume Manager have little or no application service disruption and the original copy will stay intact while the second copy is being made. The disadvantages of this approach include:

￿Host cycles are utilized.

￿It is labor intensive to set up and test.

￿Application delays are possible due to dual writes occurring.

￿This method does not allow for point-in-time copy or easy backout once the first copy is removed.

8.5.2Basic commands

Basic commands such as cpio (in a UNIX environment) or copy (in a Windows environment) are common and easy to use. The disadvantages of basic commands are:

￿Length of service disruption varies by commands used.

￿They are tedious to handle large amount of LUNs.

￿Command scripting is prone to human error.

￿Security file level access issues can arise, depending on which commands used.

8.5.3Software packages

The user can have data migration, backup or restore packages, and database tools to migrate data. An example of a data migration package is BRMS (Backup Recovery and Media Services). Tivoli Storage Manager (TSM) can also be used in a backup and restore fashion to achieve data migrations. DB2 utilities and tools such as unload, load and copy may also be used to migrate data. Other third-party data migration, backup and restore, and database packages are available. Contact the respective vendor for further assistance.

The advantages of using software packages are:

￿Small application impact when using data migration package.

￿Little disruption for non-database files.

￿Backup or restore cycles offloaded to another server.

￿Standard database utilities.

The disadvantages of using a software package are:

￿Cost of data migration package.

￿Bigger impact and or disruption with large databases due to lack of checkpoint-restart abilities.

￿Possibly lengthy application outage to backup and or restore environment.

￿Application service interruption.

8.5.4Remote copy technologies

Remote copy technologies include synchronous and asynchronous mirroring. They include Metro Mirror, Global Mirror and Global Copy.

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IBM DS6000 Series manual Operating system mirroring, Basic commands, Software packages, Remote copy technologies