Sun Storage 3510 FC Array
 
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Sun Storage 3320 SCSI Array
 

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The cache mode displayed with  sccli "show cache-parameters"  command may not be accurate and reflect the current cache state of the array. This is only true for versions 2.0 and older of the sccli software.

Applies to:

Symptoms

 * cache-parameters
mode: write-back
optimization: sequential
sync-period: disabled

The cache mode displayed as a result of the above command is not dynamic, meaning that
if the cache mode changes, the "show cache-parameters" will continue
to report the earlier mode. The only way of finding the actual cache status was to look
for the following message in the event log:

[Primary]       Alert
Force Controller Write-Through on Trigger Cause

OR

From the telnet/serial interface, check the banner of the initial screen for

the "WT" which indicates that the cache mode has turned to "write through":

Tue Jan  4 10:35:48 2005        3510     - 3510D        Cache Status: Clean
WT

Changes

Cause

Please see Sun Bug ID 6219384. The version that actually fixes the bug is unclear.

Upon testing, it was found that sccli 2.1.1 fixes this problem
for SE3510, SE3310 and SE3511 however this wasn't fixed for SE3320.
Sccli 2.2.0.3 fixes this for all minnow products.
The recommended solution is to upgrade to the latest available sccli software version
(currently 2.5).

Solution

This issue was resolved with sccli 2.2 and later software, which has added the parameter:
"current-global-write-policy" which will indicate the actual cache mode. The cache mode
may have changed to "write-through" due to one of the triggers found in the 4.x firmware,
for example a controller failure.

If a controller failure occurs, we would get the following event logged :

Tue Jan  4 09:03:27 2005
[Primary]       Alert
Force Controller Write-Through on Trigger Cause

Now running the "show cache-parameters" command will display:

sccli> show cache
mode: write-back
optimization: sequential
sync-period: disabled
current-global-write-policy: write-through

The "current-global-write-policy" will tell us the actual cache status which indicates
that the array currently is running in write-through mode and action(s) need to be taken
to address the root cause accordingly.

This solution has no attachment