Planning SnapVault

Planning primary and secondary qtree locations

Some planning of your primary system qtrees or Open Systems directories and their corresponding secondary system qtrees is helpful. Multiple primary system qtrees from multiple volumes and multiple Open Systems directories can all be backed up to corresponding secondary system qtrees in a single volume. The maximum number of secondary system qtrees per volume is 255.

Primary system qtree or directory location example	Corresponding secondary system qtree location example
systemA:/vol/vol1/qtreeAA	sv_secondary:/vol/sv_vol/qtreeAA
systemA:/vol/vol1/qtreeAB	sv_secondary:/vol/sv_vol/qtreeAB
systemB:/vol/vol1/qtreeBB	sv_secondary:/vol/sv_vol/qtreeBB
winsrvrA:c:\melzdir	sv_secondary:/vol/sv_vol/melzdir
ux_srvrB:/usrs/moz_acct	sv_secondary:/vol/sv_vol/moz_acct

Planning SnapVault backup schedule and Snapshot retention

On storage-based primaries and SnapVault secondary storage systems, the data to be backed up is captured and preserved in Snapshot copies.

On the primary storage systems, plan the intervals at which to create SnapVault Snapshot copies of your primary system qtrees.
Note
On Open Systems primary storage platforms, Snapshot copy planning and creation does not apply.
On your SnapVault secondary system, plan the intervals at which you want to update your secondary system qtrees with data transferred from primary storage platforms, and create SnapVault Snapshot copies to retain that information.
Plan how to limit the combined total of Snapshot copies retained on any one volume of the SnapVault secondary system to 251 or fewer.
Caution
The combined total of Snapshot copies retained on each volume of the SnapVault secondary storage system cannot exceed 251. If the number of Snapshot copies per volume limit is reached and the old Snapshot copies are not deleted, SnapVault will not create new Snapshot copies on that volume.

Before you start SnapVault configuration, use a table like the one below to plan how many Snapshot copies you want per volume, when you want them updated, and how many of each you want to keep. For example:

Hourly (periodically throughout the day)
Does the data change often enough throughout the day to make it worthwhile to create a Snapshot copy every hour or every two hours or every four hours?
Nightly
Do you want to create a Snapshot copy every night or just workday nights?
Weekly
How many weekly Snapshot copies is it useful to keep?

Snapshot intervals	Primary storage: when created	Primary storage: Snapshot copies retained	Secondary storage: when created	Secondary storage: Snapshot copies retained
weekly	sat @19	4	sat @ 21	8
nightly	mon-fri @19	10	mon-fri @20	60
hourly	@7-18	11	@8-19	120
Total	n/a	21	n/a	188

In the preceding example, the user is assumed to have 12 qtrees on the secondary storage system volume. On the secondary storage system, the user schedules

A weekly update every Saturday at 9:00 p.m. and keeps 8 of them
A daily update every Monday through Friday at 8:00 p.m and keeps 60 of them
An hourly update every hour from 8:00 a.m. to 7:00 p.m. and keeps 120 of them

The result in this example is that 188 Snapshot copies are being kept in the SnapVault secondary storage system volume.

The limit on Snapshot copies per volume is 251, so the 188 Snapshot copies scheduled in this example do not exceed the volume limit.

If you need to retain more than 251 Snapshot copies

If you determine that you need to retain more than 251 SnapVault Snapshot copies on the SnapVault secondary storage system, you can configure additional volumes on the secondary storage system. Each additional volume can support 251 additional Snapshot copies.

Estimating the initial backup time

The backup time required for the initial transfer of data from the primary storage system to the secondary storage system depends on the inode count of the primary data to be backed up. SnapVault can carry out initial backup at an approximate rate of 7 million inodes per hour (110,000 inodes per minute).