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Recommended Maximum Compressed Volume Size for Spectrum Virtualize Products

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Abstract

This article contains updated recommendations on maximum size of compressed volumes in standard pools.

Data Reduction Pools, and thin-provisioned volumes in standard pools, are unaffected.

Content

Spectrum Virtualize products (including SVC, Storwize and Flashsystem V9000) support Realtime Compression (RTC) for volumes in standard pools.
The system polices a limit of 96 TiB for RTC compressed volumes. In rare circumstances, it is possible for very large volumes to provoke I/O delays in the compression software which can cause node warmstarts and temporary loss of access to data.
While most systems will not have any RTC compressed volumes that are approaching this size, it is recommended to review the system configuration and take action to reduce compressed volume size if necessary.
The new recommended maximum volume size for RTC compressed volumes is:
  • 16TiB, for volumes in a pool with any non-Flash/SSD storage
  • 32TiB, for volumes in a pool that only contains Flash/SSD storage 
Recommended actions
If any compressed volumes exceed the recommended maximum size, consider taking one of the following actions:
1. Use host mirroring to migrate the data to multiple smaller compressed volumes, or a single non-compressed volume.
2. Convert the large compressed volume to thin-provisioned or fully-allocated using the "change data savings" feature of the GUI.
Thin-provisioned or fully-allocated volumes are not subject to the recommended maximum size. If there are multiple volumes to be converted, it is recommended to convert them one at a time.

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Document Information

Modified date:
13 August 2019

UID

ibm10957099