MSA1500cs best practices

[Digex]

I cannot find my original post so I need to repost.

I cannot find a best practice guide when configuring arrays or luns. Can somone point me to one? I am about to wipe our current configuration and redo it since we just got a EVA4100 for high speed databases.

Our system:

MSA1500cs 2 controllers Active/Active
4 shelves
28 146GB disks
28 300GB disks

I keep hearing not to create a raid 1+0 set of 28 disks and slicing off luns from it. Which I planned to do.

So what is the max number of disks supported in a array? I know the max number of luns is 32.

If you create multiple LUNS from a large array can you delete the original LUN you created after you created 4 others? I thought it was a yes since it is much like a Smart Array 6404 controller.

Much help is needed please post any guides or documents you can find or tips. I have looked at all the HP Reference guides with no help.

[Digex]

Well after searching the forums I keep reading that you cannot delete the last logical volume in a array. Is this true? If that is the case I will have to create a array for each logical drive on my MSA. Won't this affect the max number of disk arrays created for the MSA? Im more confused than before.

[James Muell · Accepted solution]

On the MSA platform, for any array created you can create multiple luns and them for different servers.
Deleting luns on an MSA array is restricted in that if you create luns 1,2,3,4 on array A, you have to delete them in reverse order 4,3,2,1. So you need to plan carefully and do the math to see how many arrays you need to create to support all the luns you need. If you are using MSA FW v7.00 you can spread the active luns across both controllers to balance I/O.
The downside is when you need to change or grow a lun or want to remove one completely. Unless its the last lun created on the array it will just sit there unused.

[Digex]

That is what I figured. Now I have to find out how many actual Arrays are allowed on the MSA. I dont like creating multiple logicals since our environment changes so much.

Here is a good document on found on MSA and Array configurations best practices.

http://h71019.www7.hp.com/ActiveAnswers/downloads/4AA1-0172ENW.pdf

[Uwe Zessin]

The MSA1000 controller module which is used in the MSA1000 + MSA1500cs supports up to 32 logical disks. I have never tried it myself, but I guess it also supports that many disk drive arrays.

As the maximum number of SCSI disk drives is 42 (MSA1000) or 56 (MSA1500cs) you would have to use several single-disk drive arrays, or - ugghh - start using MSA20 enclosures.

[James Muell]

If the math doesn't workout so that you have a raidset for each lun you need, you should consider adding a 3rd disk shelf to give yourself the most flexibility.

[Uwe Zessin]

My last paragraph was cut.

I meant to say that you would have to use disk drive arrays made of a single disk drive to reach that limit (32 arrays) when sticking to SCSI disk drives.

[Digex]

Well 32 Logicals is different than how many arrays. An array is basically a disk group. If you say I can create 32 disk groups I dont think that is supported. Then again Im not sure. The EVA's only support 7 disk groups max. Why would the MSA be more?

[Uwe Zessin]

The EVA 3000/4x00 support 7 disk groups, because you need at least 8 disk drives per group and the maximum is 56 disk drives. The EVA5000/8x00 supports 16 disk groups.

The MSA can deal with disk drive arrays smaller than 8 disk drives.

[Digex]

Ah ha! Now we are getting somewhere. That makes more sense. 7x8disk=56 disks. Why didnt they just put that in the manual to make it easier for me to understand. LOL. Now I just hate the fact that you cannt delete logical drive 1 without first deleting logical drive 5,4,3,2 then 1. Oh well you cant have it all. Thanks.