MSA1000 x 2 configuration question...

[Jeff V.]

This will likely be a really dumb question (or two) but I'm new to the MSA units.

We inherited two of them from a site closure for our test lab. We aren't currently interested in clustering or HA, but would like maximized disk space and performance for a VM image library.

One of the MSA1000's (unit#1) has 2 controllers and two SAN switches. The other (unit#2) has only one controller and one SAN switch. unit#1 only has one GBIC in the primary switch and 4 GBIC's in the secondary swtich. unit#2 has only 1 GBIC.

QUESTIONS:
Can I cascade them so they function as one?

If so, can I only use the SCSI connections, or can I use fiber?

If fiber can be used, do I connect SAN switch in unit#2 to the SAN switch in unit#1 then connect the hba's to the switch in unit#1, or do I connect each unit directly to an hba on the host?

If using the SCSI connections, do I connect A to B or A to A?

If either can be used, are there benefits or limitations to either method?

I'm still searching the site for docs to help, but I haven't found what I need yet. Most docs deal with clusters/failover/HA.

Any help is much appreciated!

[kunalsahoo]

Hi Jeff,

it is not possible to combine 2 MSA's and ask them to behave like 1....
if you want to use the storage space then you can only add the disk enclosures from MSA2 to MSA1...and can have both the controllers to manage.......

the question which i have for you is..
1 How you are planning to connect the disk enclosure of 1 MSA to other MSA controller as the scsi ports would be already occupied for the same MSA connection ?

[Jeff V.]

Thanks for the response. You asked how I was planning on connecting them? I don't have a plan yet. The intent of my post was to see what was possible.

On the back of both, is the SCSI module (I didn't mention that earlier because I assumed it was standard) with two ports labeled A and B. I hoped that it might be possible to connect the 2nd MSA to the first, possibly using the SCSI ports, so that the 2nd MSA behaves basically like an expansion enclosure.

Once I get them racked and hooked up, I might try it, but I was hoping to get some guidance on what the possibilities were. I believe the way they were connected had each attached to the same host via two different HBA's (though I have three hba's to work with). I thought it might be better to cascade the two via the SCSI ports (or fiber if supported) and see if the built-in SAN switch supported trunking two (or three) HBA's/fiber ports for increased throughput.

Like I said, I'm new to this hardware.

[kunalsahoo]

Hi Jeff,

no way you can cascade both MSAs...i.e...3controllers managing all the disk enclosure....

how ever you can expand one msa with only the disk enclosures of the other msa..

so the Bottom rule is ..in MSA MAX 2 controllers....

[Uwe Zessin]

The MSA1000 controller module has 4 SCSI busses and both controllers share the busses. The first two busses go to the internal disk bays (7 bays per bus). The remaining two go to the I/O module's A+B ports and can only be used to connect one or two external disk drive enclosures.

Do not confuse the MSA1000 with the MSA500 which looks similar, but does provide parallel SCSI connectivity for servers.