IBM Support

Re-enabling write cache in IBM Data Storage 3000 Series

Troubleshooting


Problem

A status of write cache suspended for the logical drives can cause write cache poor performance.

Symptom

Slow I/O

Cause

In IBM DS3000 Series whenever there is a status of write cache suspended for the logical drives, it can cause write cache poor performance due to slow I/O

Environment

Smart Analytics System

Diagnosing The Problem

Open the Logical Drives section on the Storage Subsystem Profile to confirm the status on the write cache is "currently suspended"

Read cache: Enabled
Write cache: Enabled (currently suspended)
Write cache without batteries: Disabled
Write cache with mirroring: Enabled (currently suspended)

Resolving The Problem

1. Go to the Data Storage Manager -> Tools -> Execute Script
2. Run the following commands to turn off the write cache completely:

set allLogicalDrives writeCacheEnabled=false;
set allLogicalDrives readCacheEnabled=false;
set alllogicaldrives mirrorcacheenabled=false;

3. Run the following commands to turn the write cache back on:

set allLogicalDrives writeCacheEnabled=true;
set allLogicalDrives readCacheEnabled=true;
set alllogicaldrives mirrorcacheenabled=true;

4. Repeat step #1 to confirm the status on the write cache does not show the "currently suspended" status anymore.

5. If status has not changed reboot the controllers one at the time.

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Document Information

Modified date:
16 June 2018

UID

swg21659978