● Performance When Using the Deduplication/Compression Function
The ETERNUS DX performs data deduplication/compression in synchronization with the I/O from the server.
• Using this function in environments where random access occurs is recommended. Data is intermittently
stored in Deduplication/Compression Volumes because data is appended.
• I/O response may significantly degrade when compared to systems that do not use the Deduplication/
Compression function.
• Using this function in environments where the I/O size is 32KB or smaller is recommended. The
performance is affected in environments where the I/O size is large because data is deduplicated and
compressed every 8KB.
• If the I/O size or the boundaries of the I/O address are not 8KB, the performance is affected because the
parts less than 8KB are read in the
ETERNUS DX.
• If I/Os are issued to the Deduplication/Compression Volumes, the CPU usage rate increases. The
performance of non-Deduplication/Compression Volumes may also be affected.
• The controller that controls the data reduction process of the Deduplication/Compression function is called
the data reduction CM. By replacing the data reduction CM assigned to the Deduplication/Compression
Volume, the memory and load of the CMs can be balanced during the data reduction process.
Note
• The performance may decline when the Deduplication/Compression function is enabled. The
Deduplication/Compression function is not recommended for volumes used to store performance-
sensitive data.
• Batch process (or sequential access) performance significantly degrades because data is written to
drives intermittently or a large amount of references and updates occur. In environments where
sequential access occurs, using the Deduplication/Compression function is not recommended.
• The Deduplication/Compression function becomes a disadvantage in terms of performance and
capacity if a volume stores data such as videos to which deduplication/compression is not effective
and the volume is set as a Deduplication/Compression Volume. Only enable either the Deduplication
function or the Compression function.
● Configuration Method
• Enabling the Deduplication/Compression function
From ETERNUS Web GUI or ETERNUS CLI, enable the Deduplication/Compression function for the TPP. Not
only can the Deduplication/Compression function be enabled, but the Deduplication function or the
Compression function can be individually enabled.
The Deduplication/Compression function can be enabled by performing one of the methods below.
Table 58 Method for Enabling the Deduplication/Compression Function
Condition of the TPP Chunk size (*1) Creation method
New TPP (recommended) 21MB During the TPP creation, select the Automatic mode and specify the
Deduplication/Compression function option to enable it
21MB (default) –
336MB (*2)
During the TPP creation, select the Manual mode and specify the
Deduplication/Compression function option to enable it
Existing TPP 21MB – 336MB (*3) Select a target TPP to enable the Deduplication/Compression function
(*4)
*1: The chunk size can be checked in the list display of the TPP.
*2: The chunk size can be changed only if the maximum pool capacity is selected. Select the chunk size (21MB – 336MB) from
Advanced Settings. For normal operations, the default value (21MB) does not need to be changed.
3. SAN Functions
Operations Optimization (Deduplication/Compression)
132 Design Guide
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