314 Administering volume snapshots
Cascaded snapshots
Figure 9-5 Creating a snapshot of a snapshot
Even though the arrangement of the snapshots in this figure appears similar to
the snapshot hierarchy shown in “Snapshot cascade” on page 312, the
relationship between the snapshots is not recursive. When reading from the
snapshot S2, data is obtained directly from the original volume, V, if it does not
exist in S2 itself.
Such an arrangement may be useful if the snapshot volume, S1, is critical to the
operation. For example, S1 could be used as a stable copy of the original volume,
V. The additional snapshot volume, S2, can be used to restore the original
volume if that volume becomes corrupted. For a database, you might need to
replay a redo log on S2 before you could use it to restore V. These steps are
illustrated in Figure 9-6.
vxsnap make source=V vxsnap make source=S1
Original
volume
V
Snapshot
volume
S1
Snapshot
volume
S2
