Lifespan Based On Business Uses; Establishing The Number Of V-Vols - Hitachi AMS2100 User Manual

Lifespan based on business uses

Establishing the number of V-VOLs

2-4
Hitachi AMS 2000 Family Copy-on-Write SnapShot User Guide
Hours to copy a V-VOL to tape = 3 hours
V-VOL lifespan => 3 hours
• If the snapshot is to be used as a disk-based backup available
for online recovery, you can determine the lifespan by
multiplying the number of generations of backup you want to
keep online by the snapshot frequency. For example:
Generations held = 4
Snapshot frequency = 4 hours
4 x 4 = 16 hours
V-VOL lifespan = 16 hours
• If you use snapshot data (the V-VOL) for testing an application,
the testing requirements determine the amount of time a
snapshot is held.
• If snapshot data is used for development purposes, development
requirements may determine the time the snapshot is held.
• If snapshot data is used for business reports, the reporting
requirements can determine the backup's lifespan.
V-VOL frequency and lifespan determine the number of V-VOLs your
system needs per P-VOL.
For example: Suppose your data must be backed up every 12 hours,
and business-use of the data in the V-VOL requires holding it for 48
hours. In this case, your SnapShot system would require 4 V-VOLs,
since there are four 12-hour intervals during the 48-hour period. This
is illustrated in Figure
•
Figure 2-1: V-VOL Frequency, Lifespan
Planning and design
2-1.