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bah
Contributor
Contributor

Clarrion CX 40 : Number of splindles, RAID levels, Size of LUNs ?

Hi Guys,

We are planning to virtualize our production, dev, qa, staging environment using IBM x3650s + cx40 in the back end.

in our environments we will virtualize the following:

  1. DEV environment : web servers, database servers ( sql 2005 clusters using RDM), application servers ( reporting)

  2. QA environment : web servers, database servers ( sql 2005 clusters using RDM), application servers ( reporting)

  3. Staging environemtn : web servers, application servers.

  4. Production : web servers, application servers

Now I havent seen any documentation in terms of guidance to carving our LUNs, I would like to know what is the sweet spot and works for most of the VI users in their environments or if guys could point me to some documentation that will help me :

  • decide number of LUNs

    • what is the sweet spot for number of machines per LUN

    • Number of spindles behind the LUN

    • What RAID level ( I would prefer to use RAID 5, dont have too much storage to work with right now ( 11.5 TB raw )

I know most of the answers to this would be " it depends ,.,,, ", but I would still like to see some numbers and best practises in the real world and what works.

thanks for your help.

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5 Replies
MartijnLo
Enthusiast
Enthusiast

Your EMC consultant will be able to add to this but here's our setup:

  • RAID 5 groups of 5 300GB disks.

  • This results in 1070GB of net storage available.

  • Split it in two LUNs of 535 each

In your case you could choose to do RAID5 groups of 8 disks and end up with roughly the same LUN size but divided over more disks. There is a whole heap of discussion around here about LUN sizes but staying around the 500GB per LUN seemed to be the consensus view when we planned our deployment about a year ago.

epping
Expert
Expert

Clariions work best in 41 RAID groups, if u need more spindles (i doubt it unless u have got something that pushes hard) go for a meta LUN across 2 RAID groups made up of 41. 500GB LUNs works in my environment.

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TheRealJason
Enthusiast
Enthusiast

Do you have any history on the "4 + 1 RAID groups work best" statement? We are currently running a CX-700 and have some larger RAID groups, and I have been trying to find a good reason to change it one way or another, larger or smaller. It always seemed that more spindles was better, but if there is information to back up the 4+1, I would be extremely interested in it.

epping
Expert
Expert

i went on the EMC Clariion performance course and the instructor stated that the algorithms used in the code provide for best performance on a 41, 81 is OK but a meta using 2 41 will be much better. If you go over 81 you start to get a performace hit. This is for RAID 5, the Clariion is a strange beast, DB admins always say that you get better performance on RAID 10, not always the case on a Clariion RAID 5 can give you better performance under certain DB loads.

i will try and dig up some stuff on it, if u can get on the course it is very good, the guy was Steve Stead he is based in the UK but i think he does the US as well.

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bah
Contributor
Contributor

This is very interesting , but what about carving LUNs from it

So a sample config that you are talking about would be ?

RAID Group 1 : 4+ 1 ( 143 GB drives, usable is like 133 GB ) [ One LUN

of about 532 GB)

RAID Group 2 : 4+ 1 (( 143 GB drives, usable is like 133 GB ) [ One LUN

of about 532 GB)

META LUN = 532 + 532

In this situation you are not sharing the drives and also using the most

amount of spindles.

But if we carve out multiple LUNs from the RAID groups to start with,

which will translate to multiple META LUNs, then I would assume that the

performance will take a hit.

Kamran Khan

Web Server Operations

NYC Department Of Education

Desk: 718 935 3073

Email: kkhan@schools.nyc.gov

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