Adding new drives to 3PAR 7400

[inex_77]

Hi

We have added a lot of new shelves and drives to an existing 7400 system.
Tune system was started and it took about 4 days to complete, but
the data is not spread equally over the drives. Some drives have 44% and other
13% allocation. Should I start tune system again?

-inex

[inex_77]

There is a bug in the code which sometimes causes the 3PAR not to level out data over alle available disk drives. (see below).
Solved this by changing the rpm speed from default to 10K on the cpg, using cli. (do not use gui for this)
Then ran another tune system.

-inex


CAUSE:The situation is that tunesys makes every attempt to not do any extra work that it does not need to do. And to that end when tunesys gets to the LD tuning phase it checks to see if any changes have occurred between the VV's CPG characteristics and the current characteristics of the CPG that was used to create the VV's. If there is no change it falsely assumes that no tuning is required
FIX:To workaround this have the customer alter their CPGs to also include the -rpm setting (or another irrelevant change of your choice that would alter the "characteristics" of the CPG while not changing the set of disks it selects from) and then execute tunesys with the -dr to again check to make sure we get the LD tuning we desire.
Once the dry-run completes successfully tunesys can be run to execute the necessary steps

[hdtvguy]

We run into this all the time when you want to re-balance an array. You need to get support to run some special commands to actually force the re-balance, it is not a tunesys if I recall. First line support will not know what to do you need to get the case escalated and possibly invoke your account team.

[inex_77]

Looks like the rebalancing has stopped. Some drives has 20%, others 30% of data.
I will contact support again.

-inex

[Cleanur]

As above this is known issue which is easily fixed by modifying CPG properties.

I'm told this is fixed in the upcoming 3.1.3 release

[inex_77]

I did modify the cpg properties and then did a tunesys, but I still have a variation in allocation on the pd's from 22% to 33%.

[storageguy]

We tried several tunesys commands when adding drives with almost no success each time. Eventually we had to get in touch with an engineer that had a hand in writing the tunesys scipt. He wrote an sh script for us that we used to correctly tune the drives.

[inex_77]

Thanks for your input. Do you have the name of that Engineer?

[storageguy]

Yes but I am sure he wouldn't be happy with me giving out his information. I'd ask your sales team to get you in touch with the people that wrote tunesys. That is what I did.

[inex_77]

Ok, that's fine. Thanks for your help