VMAX thin meta volumes for ESX 4.X

If you want to be able to expand them later easily concatenate them. 

If you are concerend about the I/O rates and needing to destage data quicker to the disk drives you can stripe them.

Agreed. For Enginuity code earlier than 5875 we recommend thin concantenated metavolumes because in earlier codes you can not expand a striped metavolume online. If you are to upgrade at some point to 5875 our recommendation would be to use striped metavolumes and online expansion was added in 5875 and SE 7.2. So if expansion is a concern i would stick with concatenated unless you think you might be upgrading before you would need to expand.

The maximum performance of a striped meta will be better, but the destage rate given the same pool configuration will be the same.  Writes to cache will be faster however with a striped meta.

Anyone care to post a reference to how to expand a striped meta online for ESX?

Assuming you have the correct level of Enginuity and Solutions Enabler:

symconfigure -cmd "add dev SymDevName[:SymDevName] to meta SymDevName, protect_data=TRUE, bcv_meta_head=SymDevName;" -v commit -sid

You will need to identify the devices to be added (following the rules of striped metas, same size etc...) and a BCV device that is the identical configuration of the to-be-expanded meta (matches the original metadevice in capacity, stripe count, and stripe size). So if the meta device number is 100 and you want to add devices 104 and 105 and the BCV used to temporarily store the data is device 200  on Symmetrix 3605 the command would look like this:

symconfigure -cmd "add dev 104:105 to meta 100, protect_data=TRUE, bcv_meta_head=200" -v commit -sid 3605

Once the command completes, log on to the vCenter or ESX and perform a rescan on the ESX host(s). Then navigate in the vSphere client to the Datastores panel and right click the datastore and choose Properties. Then click the "Increase" button and you will be able to select the same device that the datastore currently resides on. The ESX host will now see the device now has additional space and will ask you how much you would like to use. Choose the option that allows you to use the rest of the device and complete the wizard. This will expand the datastore to encompass the rest of the newly-expanded meta.

Refer to the EMC Solutions Enabler Symmetrix Array Controls CLI guide on Powerlink for more information on expanding metavolumes. For a pictorial and well-explained description (much better than the quick blurb i just wrote ) of this process check out page  52 of the Symmetrix/VMware techbook i wrote:

http://www.emc.com/collateral/hardware/solution-overview/h2529-vmware-esx-svr-w-symmetrix-wp-ldv.pdf

It goes through this process in detail.

Hope that helps

Cody

Thanks!