Fully Pre-Carving an EVA Array - Good or Bad?

[Alzhy]

Peter,

Glad this caught your attention..

"One of the taks that needs lots of CPU ressources in an EVA is deleting VDISKs. The larger the VDISK is and the more blocks that are actually allocated the longer it takes. "

So do you agree that pre-allocating and simply re-using VDISKS can be considered a good practice?


We currently have EVA5K's -- currently at VCS 3.028 which we are planning to upgrade to VCS 4.004 or whatever will be available early next year. The reason for this is so we can do away with SecurePath and just use DMP on VxVM. We've been using VxVM/DMP on both EVA 5K and XP disks that are currently co-presented on our HP-UX/Solaris hosts. The EVA side, it is still path protected by SecurePath and DMP ignores it.. Once we are at A/A(VCS 4.X) on the EVA5Ks - we intend to drop SecurePath and just have VxVM/DMP manage pathing/balancing on the EVA LUNS...

And with this, we will now be managing/treating EVA Vdisks as if they were XP disks... we will no longer "delete" vdisks but simply uninitialize and de-present them.

[Peter Mattei · Accepted solution]

Hi Nelson

Yes, preallocating is a good practice!

When going to VCS4.004 you need to make sure that you set your pathes correctly especially when doing heavy reads!
You know since with VCS4.x all LUNs can be accessed through both controllers and if you set round robbin you could end up doing lots of proxy reads through the "wrong" controller which means overhead!

So best is to have your preferred pathes on the LUN owning controller!
This will be adresse by implementing ALUA which for the EVA to my knowledge is currently only available for Windows with MPIO DSM 2.01.00 and Solaris with MPxIO.

ALUA means Asymmetric Logical Units Access and has been defined by INCITS T10.
You will see it more and more in the future!
Perhaps with VxVM/DMP as well?!

Cheers
Peter

PS: To make my previous post clearer: You cannot convert a container directly to a VDISK, you can use it to create snapshots or snapclones! See attached a scteenshot of CV with the button to create a container. Note that the vdisk needs to be unpresented before you get this option!