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BP1014 Enhancing SQL Server Protection using Dell EqualLogic Snapshot Smart Copies

Database Layout

 As a best practice, make sure that SQL Server® databases and associated transactions logs

should each reside in dedicated volumes. This will prevent creation of “torn” Smart Copies

during selective restore scenarios. This will also enable faster restore and recovery times for

individual SQL Server® databases.

 The Volume Shadow Copy Service (VSS) imposes a limit on the time it takes to create a Smart

Copy. Smart Copies involving many volumes might exceed this time limit (30 seconds). If this

limit is exceeded then ASM/ME displays an error message stating that VSS can no longer hold

I/O writes. To resolve this problem, the best practice is to reduce the number of volumes

included in the Smart Copy. You might also have to reduce the number of volumes assigned

to collections.

When creating ASM Smart Copies

 If your intention is to restore smart copy on a temporary basis for data validation or to restore

lost data then Side-by-Side restore of Snapshot Smart Copies is the best option.

 If you are planning to use a Smart Copy to do an “in place” restore of the database and also

need to roll forward using transaction logs, then you should make sure that all required log

backups are available before proceeding.

 Use the latest EqualLogic controller firmware. If using EqualLogic firmware 5.0 or later,

selective restore of database leverages the data copy offload feature on the EqualLogic SAN.

This feature bypasses the file system’s copy operation while restoring data, Therefore, it

completes much faster than a traditional copy operation that involves data copy from SAN to

host and back to SAN.

 By default, backup documents created by Auto-Snapshot Manager are saved as files with a

“.bcd” extension. After a smart copy set is imported, the backup document extension is

changed to “.imported”, which indicates that the backup document cannot be used again.

The location for backup documents should be managed on a central share that can be backed

up regularly. We recommend that you store backup documents on a file share accessible to

both computers.

 To promote a snapshot/clone Smart Copy on a different computer than the one that created

it, the computer must be running Auto-Snapshot Manager and must have access to the

secondary group storing the snapshot/clone set. It is recommended to give access on those

volumes to the host where the database is transported.

4.3 General backup strategy best practices

 Use of snapshots, whether they are software based or storage based, should not be

considered as a substitute for a traditional backup and restore strategy. You should first design

and implement a backup and restore strategy that is not snapshot based. After that, you should

consider how to use snapshot based tools (such as the Auto-Snapshot Manager Smart Copy

feature highlighted in this report) to compliment your backup/restore strategy to improve

flexibility in meeting specific aspects of your RPO and RTO requirements.

See the “Multiple Databases on Volumes” section in the

Auto-Snapshot Manager Microsoft Edition User Guide

for an explanation of torn Smart Copies.