3par add new disk to a cpg

[cafu2011]

Hi guys,

I'm new on 3PAR, I'm reviewing an implementation guide that I founded on the web. But I have a doubt.

Is possible to add new disk to a CPG already created?

Thanks in Advance

C.F

[Richard Siemers]

Yes. We added 2 new shelves of disks and our old CPGs immediately began to use them.

The data is not evenly distributed to the new disks though, until you use dynamic optimizer to rebalance.

[cafu2011]

Thanks a lot for your help Richard.

But then, is not necesary to do anything on the CPG configuration to add new disk??

Regards
CF

[Richard Siemers]

Yes you can edit an existing CPG... but I don't recommend that because the changes only apply to new growth. Old data will remain on the old settings until you rebalance (aka Dynamic Optimizer cli= tunevv) your data WHICH requires moving the luns from the old CPG to a new one.

Editing may be useful for capacity emergencies, however, it is at the expense of unbalancing your wide striping. I am sure there are several other unique and rare opportunities that may justify editing a CPG, I would call 3PAR support if you think you have such a need.

Rebalancing requires and expensive license for Dynamic Optimizer (DO). I believe "DO" should be a basic feature included in the core system, that functionality is too often needed to correct admin mistakes, and the most popular, widely deployed, arrays out there include this. The times I needed this and didn't own it, our 3PAR team has helped with 30 day eval keys. In theory, if you don't add any new spindles, and create your CPGs and VVs correctly the first time, you should never need DO.

If you're interested in getting down into the weeds... CPG settings dictate how new LDs (logical disks) are created. So the edits will only apply to new LDs. You could in theory, have a RAID1 cpg with data in it, then change the CPG settings to raid5, the old data (LDs) will still be at raid1, when the current LD fills up and a new one is created, it will use the new settings.

In your IMC (GUI) View --> Preferences --> Advanced, you can enable the display of Logical Disks, as well as other advanced volume properties.

[brutus333]

Hi!
I have a different question on same topic:
Let's say that I have one CPG on SSD devices with "-p -devtype SSD -rpm 150" (all SSD devices) and I am adding new SSDs.
Will new LDs be created only on the SSDs available at CPG creation or will use also new SSDs?

Thank you in advance,
Virgil

[Richard Siemers]

Newly created LDs for your existing CPG will use the new SSDs as soon as they are online and available since they meet both criteria "SSD" and rpm "150".