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Planning and Design 2–9
Hitachi Simple Modular Storage Copy-on-Write SnapShot User’s Guide
3. Multiply the base data pool size by the number of V-VOLs. Thus:
4 V-VOLs x 625 GB = 2500 GB (2.5 TB).
Data Pool Key Points
• The data pool must be on same controller as the P-VOL and V-VOL(s).
• Data pool capacity should be at least 20 GB.
• Up to 64 volumes can be assigned to a data pool.
• When a volume is assigned to a data pool, it is no longer recognized by
a host.
Calculating Maximum Capacity
Simple Modular Storage manages capacity for in-system replication
systems in segments of 15.75 GB for P-VOLs and 3.2 GB for data pools. As
a result, your local replication system’s managed capacity must be
calculated using the formulas provided below and compared to the
maximum supported capacity.
To calculate SnapShot capacity
1. List the size of each P-VOL in the Storage system. For example:
P-VOL 1 = 100 GB
P-VOL 2 = 50 GB
2. Calculate managed P-VOL capacity, using the formula:
ROUNDUP (P-VOL capacity / 15.75) * 15.75
For example:
P-VOL1: ROUNDUP (100 / 15.75) = 7
7 * 15.75 = 110.25 GB, the managed P-VOL Capacity
P-VOL2: ROUNDUP (50 / 15.75) = 4
4 * 15.75 = 63 GB, the managed P-VOL Capacity
3. For each P-VOL, list the data pools and their sizes. For example:
P-VOL1 has 1 data pool whose capacity = 100 GB
P-VOL2 has 1 data pool whose capacity = 60 GB
4. Calculate managed data pool capacity, using the formula:
ROUNDUP (data pool capacity / 3.2) * 3.2
For example:
P-VOL 1 data pool: ROUNDUP (100 / 3.2 = 32)
32 * 3.2 = 102.4 GB, the managed data pool capacity
P-VOL 2 data pool: ROUNDUP (60 / 3.2 = 19)
19 * 3.2 = 60.8 GB, managed data pool capacity
5. Calculate maximum capacity using the following equation:
(Total P-VOL capacity) / 5 + (Total Data Pool capacity) < = 800 GB
For example: