Planning your Exchange storage requirements

About the requirements

For SnapManager backup and restore to function, the Exchange data store must be located properly on one or more LUNs, and those LUNs need to be sized appropriately. The ability to restore individual databases, new in this version of SnapManager, requires additional data configuration restrictions.

Read this entire section, then plan your SnapManager Exchange data store LUN and filer volume requirements, based on your space and functionality requirements.

For some sample SnapManager configurations, see Sample SnapManager configurations. For more information about SnapManager for Exchange data store configuration, see the SnapManager for Microsoft Exchange Best Practices Guide.

Note
The version of Exchange that you are running does not affect your configuration requirements.

Data storage requirements for Exchange 2000 and 2003

Exchange 2000 and 2003 have the following data storage configuration requirements:

There can be between one and four storage groups in an Exchange server.
A storage group contains from one to five databases.
For Exchange 2003 only, there can be a fifth storage group called the Recovery Storage Group. SnapManager does not support backing up or restoring to this special storage group.
Note
The presence of a Recovery Storage Group can interfere with SnapManager's ability to perform a restore. For more information, see Exchange Recovery Storage Group incompatibility with SnapManager Restore.
In a Windows cluster, there are one or more Exchange virtual servers. The totals for the entire clustered system cannot exceed the specified limits.
For example, there could be four Exchange virtual servers with one storage group each, or one Exchange virtual server with four storage groups, or any combination in between, as long as the maximum number of storage groups is not exceeded.

Data storage requirements for Exchange 5.5

Microsoft Exchange 5.5 has the following data storage configuration requirements:

Each Exchange server has one Information Store and one Directory Store.
Note
These stores correspond to storage groups for this document.
The Information Store can have up to two databases, pub.edb and priv.edb.
The Directory Store has only one database, dir.edb.

SnapManager rules for Exchange data store configuration

The following rules apply when you are configuring your Exchange data store for SnapManager 3.1 for Microsoft Exchange, for all supported versions of Exchange.

Note
These rules are enforced by the SnapManager Configuration Wizard.

Exchange databases cannot share a LUN with databases from different storage groups.
Note
For Exchange 5.5, this means that the Information Store and the Directory Store must be on separate LUNs.
Exchange databases cannot share a LUN with transaction logs, even if they are from the same storage group.
Transaction logs from different storage groups can share a LUN with each other.
The SnapInfo directory can have its own LUN, or can share a LUN with transaction logs. It cannot share a LUN with Exchange databases.
All databases on a LUN are restored together. To be able to restore an individual database without restoring the rest of its storage group, that database must have its own LUN.
Nothing can be stored on the Exchange LUNs except what SnapManager for Microsoft Exchange puts there.

Recommendations for Exchange data store configuration

For best results, consider the following Exchange data store recommendations:

Do not place LUNs containing data from different Exchange servers in the same volume.
This recommendation helps you avoid several problems:
- SnapManager backups created for another Exchange server on the same volume use up snapshots for that volume but are only restorable for the Exchange server they were taken for.
- Conflicting backup schedules between the two Exchange servers can lead to creating "busy snapshots".
Do not place LUNs in the filer's root volume.
The root volume is reserved for use by Data ONTAP.
For faster restores, use the minimum number of LUNs required for your restore requirements.
Unless individual database restoration is a requirement in your environment, group your databases together.

Drive letter limitations and individual database restoration

Windows supports up to 26 drives. SnapManager needs one drive letter free to perform backups, verifications, or restores, so you can allocate up to 25 drives, but no more.

Databases that need to be restored individually each require their own LUN and drive letter. For Exchange 2000 or 2003, if you have a large number of databases to be individually restored, you might run out of drive letters. To avoid this, determine which databases must be restored individually, and which can be combined on a LUN with one or two other databases (all of which are restored together).

Caution
If you do not reserve at least one free drive letter for SnapManager, SnapManager cannot function properly. This requirement also applies to hosts running remote verification.

Considerations for converting to individual database restoration

If you are upgrading an existing SnapManager implementation and you are creating new LUNs to use individual database restore, your space requirements increase. This is because the database must be copied from its current location to the new location; in effect, it exists in both places until the move is complete. Depending on the size of the volume containing both LUNs, you might need to increase the volume size.

For more information about sizing your volumes, see Volume size calculation. Remember to include both the old and new LUNs when calculating the volume size.