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3x DS2100 and a A5856A 4si RAID

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Thomas Warren_1
Occasional Contributor

3x DS2100 and a A5856A 4si RAID

I know that there were a bunch of issues in getting several SC10's to work as RAID array's with an A5856A 4si RAID card.

On the HP site, it claims the DS2100, can easily be configured as a low-cost RAID array in conjunction with a PCI array controller.

Can I attach 3x DS2100 array's in single bus config to 3x of the 4x ports on the RAID card?? will this be a simple, cheap, albiet not 100% redundant method of protecting a fixed amount of data??

Any alternate proposals??

thanks
6 REPLIES
Ron Lawson_1
Trusted Contributor

Re: 3x DS2100 and a A5856A 4si RAID

Sure, you can do that. Just remember to always use single bus configurations with the RAID 4si card.
Thomas Warren_1
Occasional Contributor

Re: 3x DS2100 and a A5856A 4si RAID

Thank, you just out of curiousty can you explain why the single bus is important, with 3x systems and only 4x ports that is what we will be doing with each DS2100 properly terminated.

But we were also looking at 2x ds2100 dual buss to the 4x ports. why would this be bad?

thanks for the help
Ron Lawson_1
Trusted Contributor

Re: 3x DS2100 and a A5856A 4si RAID

You cannot connect two of the RAID 4si channels to a single SCSI bus because each of the 4si channels uses SCSI ID 7. The result is constant communication errors on the SCSI bus and an inability to access any of the data on the drives.
Vincent Farrugia
Honored Contributor
Solution

Re: 3x DS2100 and a A5856A 4si RAID

Hello,

You cannot do that because actually, although you have 2 SCSI ports on your ds2100, those are connected to the same controller. There are two for the simple reason that the DS2100 can be daisy-chained. Actually, you can put all your 3 ds2100 daisy-chained to a single controller. 12 disks on a single controller. So putting 2 RAID connectors to the same controller doesn't make much sense.

HTH,
Vince
Tape Drives RULE!!!
Thomas Warren_1
Occasional Contributor

Re: 3x DS2100 and a A5856A 4si RAID

Interesting, Thanks, that was very helpful.

Which brings up another question. (by the way we have started the proedure to purchase these ds2100 systems from HP.)

Should we hook up the 3x ds2100's to the 4si RAID card seperately

OR

daisy chain the three and only have one connection to the 4si RAID card??

what are the pro's and con's?? your thoughts??
Vincent Farrugia
Honored Contributor

Re: 3x DS2100 and a A5856A 4si RAID

Hello, (again)

Well on a RAID level, it doesn't make much difference, but for performance reasons, it does make a difference. If you connect the ds2100 separately to the 4Si, that would make it more performant, because you're splitting IO through the 3 difference connectors. Also, if you daisy-chain the ds2100s, and happen to have a controller failure on the first ds2100, you'll lose connectivity to all disks, whereas if you put them sepearately, you'll only lose access to those specific ds2100 disks.

HTH,
Vince
Tape Drives RULE!!!