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Chapter 8: Advanced Volume Operations 8-11
volume create –activate snapshot –vol Snapshot1 –src
QATesting –dst Snapshot1 -lt 75
10254
Snapshot1
QA Testing
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AS
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Figure 8-6. 1
st
Snapshot
Figure 8-7 shows the same source and snapshot volume after a write operation
to sector 1. The original data, S, from sector 1 is first copied to the snapshot and
then the new data, B, is written to the source volume.
10255
Snapshot1
QA Testing
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Snapshot1
S
QA Testing
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Figure 8-7. Update to 1
st
Snapshot & 1
st
Write to Source
Figure 8-8 shows the creation of a second snapshot and a second write
operation to the source volume. The original data, N, A and P, from sectors 5, 9
and 13 are first copied to the Snapshot 1 & 2 and then the new data, B, E and B,
are written to the source volume.
Because snapshot volumes are independent of each other, the original data
must be written to each relevant snapshot, as in Snapshot 1 and 2. The pointer
table is only between a single snapshot and its source; never to parts of other
snapshots. Therefore, if one snapshot volume fails, no other snapshot is
affected.
volume create –activate snapshot –vol Snapshot2 –src
QATesting –ch Snapshot2 -lt 80