Hi naren,

I'm not real clear on what your question is - but I did see your earlier post about the similarities between Clariion raidgroups and Symmetrix diskgroups.

I'm presuming you're attempting to isolate the data from the backend/disk perspective. The reason I'm asking this is that not only can you physically separate your disks but Solutions Enabler allows us the flexibility of creating a creating diskgroups for manipulating luns logically as well.

Since I have the added complexity in my environment of RAID-5 7+1 striping (hey, it's ugly but I inherited it, I didn't build it!). I really wanted to physically separate the disks into diskgroups. And because of all of the databases we have inhouse - it really helps to have the Solutions Enabler diskgroup logical separation as well.

So - you can do both. I hope this helps.... Check out the symdg and symld commands.

-jq

Message was edited by:
Julianne Quinn

No, you can't. Well, you could say it, but you'd be wrong.

I'm not sure what you mean and what problem you're trying to solve (if any). You should be aware that a Clariion and a Symm are very different in how they define storage for hosts to use.

Why would you want a disk to not be a part of a disk group?

Hi Julianne Quinn

Thanks for your reply. I will check those two commands you mentioned in the mail and get back to you with right question.

Naren

Hi Jurjen,

Jut doing comparison study between symmetrix and clariion for Raidgroup and Disk group.

Because Raidgroup and Disk group has set phyicsl disks from where Lun can be formed.

So only i think concept is same with one difference which I metioned in teh first mail.

Naren

Naren23 I'm not a big Clariion fan, so I don't know them very much .. Could you please explain me what you MUST define when you create a STG in a Clariion ?? Is it correct to say that an STG is made of the following 2 items ??

* Disks
* Protection

Hah - I'm not a big Clariion fan either. And I used to work at EMC as well.
So .... who *are* the big Clariion fans?

*LOL* I guess that depends on how you define "big". Personally I prefer the medium sized CLARiiONs

But seriously, we have more capacity on CLARiiONs in our enterprise than on Symms (the DMX3s are still fairly new to us and the old 8830 was purely mainframe storage). The CLARiiONs are great if they are used properly... and it helps to understand them too.

Stefano, when you refer to "STG" are you talking about Storage Groups? If so they are very simple... An SG is a logical group which contains references to hosts and storage (LUNs). If a host reference is in the same SG as a LUN then the host can see that LUN. If they aren't in the same SG the host can't see that LUN. Basically simplified masking (in Symm terms). There seem to be advantages and disadvantages to both ways of doing it. The CLARiiON way may SEEM simpler, but isn't quite as powerful in some situations.

If you meant something else by STG then please clarify and we'll try again.

And back to the original question...

On a CLARiiON it IS possible to have a single disk, but you still need to make it a RAID group that is just one disk... then you can mind a LUN on it. There really isn't a lot of call for doing that, because you bypass the potential advantages of having RAID performance and protection on your LUNs, but if you have a need, you CAN do it.

Hmmm I wrote STG (or SG) .. but I was thinking at RAID GROUP ...

Let me straighten my question ..
When I define a Raid Group I pick up at least 1 lun (better to start with 2 luns ) and "tie" them together assigning a certrain level of protection (I.E. Raid-5) when I define (hmm bind) the first LUN. If I add another LUN to the same Raid Group I'm forced to use the same protection (Raid-5 in my example) in the same RG.

Am I missing something ??

Back to the original question .. Since a RaidGroup have a "fixed" protection while a Disk Group inside a Symmetrix doesn't have, I see no similarities between those two objects.

BTW I can have a "single-disk" Disk group even on a DMX