SANRAD V-Switch Update to 1st Snapshot & 1st Write to Source, Advanced Volume Operations 147

	QA Testing			Snapshot1
S	A	N	S
N	A	S	H
A	M	M	O
P	U	N	T
	QA Testing			Snapshot1
B	A	N	S	S
N	A	S	H
A	M	M	O	10255
P	U	N	T

Figure 78. Update to 1st Snapshot & 1st Write to Source

Figure 79, page 148 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 snapshot –vol Snapshot2 –src QATesting –ch Snapshot2 -lt 80

Chapter 8: Advanced Volume Operations 147