The size of the database, its rate of change, the frequency with which you perform backups, and the backup schedule all affect how you lay out storage. The layout for SnapMirror and SnapVault copies should be modeled on the layout for primary data.
SnapManager backs up an Exchange database by creating Snapshot copies of database data files, transaction logs, and the SnapInfo directory it uses to store information about backed up files. You use the SnapManager Configuration wizard to create one or more SnapInfo directories when you migrate databases to NetApp storage.
For each Exchange database, SnapManager requires that you configure the following:
You cannot store database files for multiple databases on the same LUN.
Logs for multiple mailbox databases can be stored on a single LUN, as long as you limit the number of transaction log streams to 9 or less.
For storage efficiency reasons, most sites create the SnapInfo directory in the same LUN as transaction logs. In this configuration, SnapManager creates NTFS hard links when it archives transaction logs to the SnapInfo directory. Archiving transaction logs using hard links is almost always more efficient than performing a file copy.
You can store the SnapInfo directory on a different LUN if you think there is some risk you will run out of space. You cannot store the SnapInfo directory on the same LUN as database files.
Restrictions are as follows:
Snapshot copies are volume-wide, so you need to be sure that items on the same volume have compatible backup schedules. Because Snapshot-copy contention issues can occur when databases from different Exchange Servers have different backup schedules, it is a best practice to store these databases on separate volumes. Similarly, because transaction logs are often backed up more frequently than database files, it is a best practice to store the database files and transaction logs for the same database on different volumes.
Ideally, you should store the database files and transaction logs for each database on a dedicated volume. This is the case even if the databases are from the same server. The following examples show the use of dedicated volumes:
You can store relatively small databases from the same server on a single volume as long as they have low transaction rates and your SLA does not require you to back up the databases frequently. In most cases, you can store transaction logs and the SnapInfo directory for each database on the same LUN, as shown in the following illustration:
The following illustration shows an ideal layout, in which the database files for each database are stored on different volumes: