topic Re: eva 5000 configuration in Disk Enclosures

eva 5000 configuration

???_185 — Fri, 03 Feb 2006 21:00:37 GMT

it is configured as default group has 57 disks of vraid5.
If I configure 50 disk in this system,
do I have to add another disk group or just add disk original disk group?
which will be more efficient in performance or operational aspects?

Re: eva 5000 configuration

Steven Clementi — Fri, 03 Feb 2006 22:05:29 GMT

HP Recommends that you try to put as many disks into a single disk groups as possible. From a price and performance perspective, this is the best choice.

This does not mean it is the right choice for you.

You will need to decide on how this space is going to be used. Do you want to extend existing Virtual Disks? Do you want to have "backup" space? Do you want to start creating Snapshots/clones? Do you want/need separate I/O for a specific application?

Generally speaking, the more disks you pop into a disk groups, the more I/O performance you can get out of it. Price wise, you save a few disks if you use only a single disk group since you will not need a protection level for the new disks. It is incorporated into the existing protection level of the group and you realize the full space of ALL the disks.

You may find that you have a specific need for an application and you want to separate out the disk access... then you need a second Disk Group. Most cases only require a single Disk Group. You may want to separate out by OS type utilizing the Disks, though not necessary... it may be easier to manage and allocate resources in the future when a group demands more space as well as keep tract of what specific groups are using more easily.

I.E. Oh, the Database group needs more space. They are running Oracle on Linux so you need to put more disks in the "Linux Disk Group" and charge their department for the disks.

Or, the Windows folks are in need of some more File Serving Space. Buy 8 disks and put them into the "Windows Disk Group". They gain slight more performance and have separate tracking of their resources.

Lots of things to consider.

Steven

Re: eva 5000 configuration

Ivan Ferreira — Sun, 05 Feb 2006 00:09:28 GMT

We have a horrible experience with single disk group and vraid 5. Disks fails very often, once, two disks failed at the same time on the same RSS and we lost ALL our VRAID5 VDISKS (not one or two, ALL).

If you are going to use VRAID5, I think that is better if you create another disk group. In this case, for availability, and fair performance. So, you could increase a little your chances with multiple disk failure. Use protection single in both disk groups.

Re: eva 5000 configuration

???_185 — Wed, 08 Feb 2006 23:59:30 GMT

What is RSS?

Re: eva 5000 configuration

Steven Clementi — Thu, 09 Feb 2006 00:24:59 GMT

RSS = Redundant Storage Set

It is how the EVA keeps track and protects your data.

For instance, if you have a Disk group with 16 disks. You will have 2 RSS groupings of 8 disks apiece. The goal the EVA tries to maintain is 8 disks per RSS, thus one of the main reasons to always add disks to a disk group, 8 at a time and to make sure the group has 8 disks or a number divisable by 8 (16, 24, 32, 40, etc.)

Steven

Re: eva 5000 configuration

Ivan Ferreira — Thu, 09 Feb 2006 00:36:34 GMT

That's right, and if two (or more) disks fails on the same RSS, your data is lost.

See the attached .doc file.