Fujitsu ETERNUS DX500 S4/DX600 S4 Design Manual page 117

3. SAN Functions
Operations Optimization (Deduplication/Compression)
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Deduplication/Compression System Volumes
The following internal volumes are created for each TPP where the Deduplication/Compression function is ena-
bled.
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/Compression function for
TPPs because the DEDUP_SYS Volume and the DEDUP_MAP Volumes are created within the maximum pool ca-
pacity.
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 usage 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 Vol-
ume 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 Vol-
ume and the DEDUP_MAP Volume. The physical capacity that is used for the control 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.
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Deduplication/Compression Volumes
The physical capacity may temporarily be larger than the logical capacity that is written because data is appen-
ded in Deduplication/Compression Volumes. If the I/O load is high, the physical capacity may run out. Monitoring
the physical capacity on a regular basis and enabling SNMP notifications are recommended.
The deduplication rate may temporarily decrease due to a CM failure, a firmware update, or a blackout.
•
• If a failure occurs in a RAID group configuring the TPP, or a bad sector occurs in the DEDUP_SYS Volume or
the DEDUP_MAP Volume, the data of all the Deduplication/Compression Volumes in the TPP may be de-
leted.
FUJITSU Storage ETERNUS DX500 S4/DX600 S4, ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Design Guide (Basic)
117
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