Fujitsu ETERNUS DX100 S4 Design Manual page 116

3. SAN Functions
Operations Optimization (Deduplication/Compression)
One DEDUP_SYS Volume
•
Two DEDUP_MAP Volumes
•
A single DEDUP_MAP Volume is created if the TPP only has one RAID group.
Check if the remaining area in the pool is sufficient before enabling the Deduplication/Compres-
sion function for TPPs because the DEDUP_SYS Volume and the DEDUP_MAP Volumes are created
within the maximum pool capacity.
Because the data after a deduplication/compression is stored in the DEDUP_SYS Volume, add RAID
groups to the TPP or expand the DEDUP_SYS Volume before the usage rate of the TPP or the us-
age rate of the DEDUP_SYS Volume reaches 100%.
DEDUP_SYS Volumes cannot be expanded to a capacity larger than 128TB. If the capacity of the
DEDUP_SYS Volume exceeds 128TB, use the RAID Migration function to migrate the Deduplication/
Compression Volumes in the TPP to non-Deduplication/Compression Volumes (TPVs) or other
TPPs.
Apart from the data after deduplication/compression, the control information is written to the
DEDUP_SYS Volume and the DEDUP_MAP Volume. The physical capacity that is used for the con-
trol information is the total of the fixed capacity of 4GB maximum and the variable capacity (1 -
15%) according to the written size from the server.
●
Deduplication/Compression Volumes
The physical capacity may temporarily be larger than the logical capacity that is written because
data is appended in Deduplication/Compression Volumes. If the I/O load is high, the physical ca-
pacity may run out. Monitoring the physical capacity on a regular basis and enabling SNMP notifica-
tions are recommended.
As with normal TPVs, the size of the used areas that are recognized by the server may differ from
the areas that are actually allocated if physical capacity is allocated to areas not used by the server.
In this case, perform one of the following area release operations.
• When using a controller firmware version V10L82 or later, release unused areas by issuing the
space reclamation (UNMAP) command from the server.
To issue the command, the space reclamation (UNMAP) function of the Deduplication/Compres-
sion Volumes must be enabled in advance by using the host response setting. For details on the
settings, refer to "Configuration Guide -Server Connection-".
For the procedure on issuing the UNMAP command, refer to the manuals of the relevant server or
OS.
• Zero out the unused areas and then execute "TPV/FTV capacity optimization" for both the DED-
UP_SYS Volume and the DEDUP_MAP Volumes.
For details, refer to
Fujitsu Storage ETERNUS DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems Design Guide (Basic)
"TPV/FTV Capacity Optimization" (page
116
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47).
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