Clearing Cache - CX700 and DMX1000

[JVB2]

I'm working with the MS SQL DBA's to try and optimize our storage for them. We are not having any specific problems right now, but we expect exponential DB growth on some of our larger databases.

We are running several tests that simulate production data to measure IO and Throughput under different scenarios:

RAID: RAID 5, RAID1+0
Partition format sizes: (64Kb, 8Kb, 4Kb, etc.)
Disk Offset settings: (Changing from an offset of 63 to 64)
Cache Settings, etc.

I'm seeing inconsistent results and believe it's related to the DMX and CX700 caching data. I'd like to clear the cache between each test so I can get a true measure of each change...

Any suggestions?

 

[Chacalinc]

in CX700 you can disable the write cache and then re-enable it, so cache will get cleared. I don't know how to do it in symmetrix, I just wait some minutes (issuing "A7," in service processor in order to see that there are no write pendings to volumes).

Cheers.

Chacal, Inc.

 

[JVB2]

Thanks for the info.

Do you have any info related to the Read cache?

We typically to bulk loads in the middle of the night and then the majority of our I/O (95%) is random reads throughout the day.

I was told by another Engineer that this wasn't possible, but since I'm a skeptic by nature, I'd like to confirm that statement.

 

[Chacalinc]

you can change the cache setting on-the-fly in the clariion, just disable both read and write cache, change the cache amount for read and write and then re-enable them. You can do it either through navicli in order to make a script to do that job (using cron or task scheduler).

Cheers.

Chacal, Inc.

 

[JVB2]

Excellent.

Now I need to figure out a way to do the same on the DMX.

Thanks for the post!

JVB