Fujitsu ETERNUS DX S5 Series Design Manual page 134

3. SAN Functions
Operations Optimization (Deduplication/Compression)
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Deduplication/Compression System Volumes
One DATA_CNTNR Volume is created for each TPP where the Deduplication/Compression function is enabled.
Before enabling the Deduplication/Compression function for a TPP, check whether the remaining capacity is
sufficient because the DATA_CNTNR volume is created just within the maximum pool capacity.
Because the data after deduplication/compression is stored in the DATA_CNTNR Volume, add RAID groups to
the TPP or expand the DATA_CNTNR Volume before the usage rate of the TPP or the usage rate of the
DATA_CNTNR Volume reaches 100%.
The DATA_CNTNR Volume cannot be expanded to a capacity larger than the maximum pool capacity. If the
capacity of the DATA_CNTNR Volume exceeds the maximum pool capacity, use the RAID Migration function
to migrate the Deduplication/Compression Volumes of the TPP to non-Deduplication/Compression Volumes
(TPVs) or another TPP. For details on the maximum logical capacity of the DATA_CNTNR Volume, refer to
Table 56 or Table
Apart from the data after deduplication/compression, the control information is written to the DATA_CNTNR
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
appended 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.
Caution
• 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 DATA_CNTNR
Volume, the data of all the Deduplication/Compression Volumes in the TPP may be deleted.
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134 Design Guide