2 node cluster with one external shared disk array: Possible?

[Patrick Hayes]

Hello All,

I'm on a budget contrained project where I'd like to deploy MCSG. 2 RP2470's + a Disk System 2300 fit the budget, but I need to know whether or not MCSG can or cannot be setup in this configuration.

The RP's each have an additional USCSI card (to connect the DS2300) & Lan card (for the heartbeat).

Boot disks in the 2470s & data disks in the 2300 are mirrored.

I realize that the DS2300 itself is a SPOF, but it's either that or retreat to a single node setup. Does anyone know whether or not MCSG can be setup using a single external disk array? I see no reason why not (It's exactly the same as a cluster using 2 DS where one is down) but I'm hearing different answers from my contacts at HP. Some say yes, some say no...

All comments welcome.
Pat

[Chris Wilshaw · Accepted solution]

Yes it is possible.

We have a cluster that has 2 servers and 1 HASS unit with 8 disks.

We have no internal disks in the servers - the HASS contains 2 pairs of mirrored boot disks, and 2 pairs of mirrored data disks.

I know it's not considered a supported configuration, but as with your case, budgetary concerns were also in place.

There is no difference in the way that this is set up, than for a "normal" cluster.

[Vincent Farrugia]

Hello,

Yes you can. This is possible because the DS2300 has 2 controllers; otherwise MCSG is not supported.

For full HA, but 1 dual-port PCI SCSI-2 card (A5150) for each server, two in total. If you want extra HA, you can buy 2 such single-port cards for each server, 4 in total (A5149A). Connect both A's to both controllers. Configure your DS2300 in SPLIT bus mode, so that you can mirror across controllers (at least). You can setup MCSG in this scenario. Wouldn't be too bad, you'll have the DS2300 backplane as an SPOF, but you can't have evetything in life.

HTH,
Vince

[Vincent Farrugia]

Hello (again),

I forgot to mention one thing in my setup. Make sure you connect from the A's (or rp2470s in your case) to the DS2300 using inline-terminated cables. Disable termination from the HBAs first.

HTH,
Vince

[Patrick Hayes]

Thanks for the replies.

Any thoughts on whether a redundant controller card in the DS2300 is of much use? The DS2300 controllers have 2 ports so adding one means that I eliminate the controller as a SPOF (but then have 2 unused ports).

Pat

[Chris Wilshaw]

I guess that depends on just how tight your budget is.

The resilience that it would provide you with would certainly be worthwhile if you can get it.

[Vincent Farrugia]

Hello,

My setup assumed you have two controllers. Having one controller throws MCSG out of thw window automatically. I cannot imagine how you can do an MCSG environment without having 2 controllers. You cannot mirror across controllers either... so if the controller fails, bye bye data until you replace it. If you can live with that, then it's all fine I guess. You will have too many reduced possibilities to be able to implement MCSG in my opinion.

HTH,
Vince