Jeff,

1) Mixing the stack types will actually work, but it's not supported due to performance issues. I have a setup like this in my environment, with two 3g and one 6g shelf on a 3g stack. It works okay, questionable throughput at times though.

Having a 6g stack on its own ports on a 3g card should not be an issue. I just put the very same online this week...

2) I don't believe you can get the 15k 3.5" drives from any vendor starting this year. The industry went en masse to the 2.5" form factor for various reasons. The smaller form factor is supposed to make up for the slower spindle speed w/r/t random read latency.

Fred

 
                 From:
                Jeff Cleverley <jeff.cleverley@avagotech.com>

                To:
                toasters@teaparty.net 

                Sent:
                Wednesday, February 27, 2013 8:33 PM

                Subject:
                DS2246 shelves and drives questions.

            Greetings,

            We will be upgrading an existing 6080 cluster to a 6280
            cluster.  We

            also have a 6080 cluster we'll be adding disks to also. 
            Both clusters

            are 7-mode.  We'll probably end up at 8.1 on both clusters. 
            My 2

            questions stem from the disks and shelves being proposed for
            the

            upgrades (ds2246 with 450g SAS).

            1.  We currently have DS4243 shelves with 600gig SAS.  I
            know I can't

            mix these in the same stack because of the 3/6gb connection

            differences.  I have a free port on each SAS adapter in our
            6080s.

            Can I put the 6gb shelves on the same adapter as long as
            they are on

            their own stack?  I'm guessing it may not be a best
            practice, but we

            don't have any slots free in the 6080 for more cards.

            2.  I found a white paper that states the 10K drive
            performance can be

            up to 20% slower than the 15K SAS drives for random reads. 
            That seems

            like a pretty big performance it.  It also says mixing the
            disks in

            aggregates is not recommended.  Other than the smaller
            footprint and

            better density, I'm not seeing an advantage over using 600g
            SAS in the

            DS4243 shelves.  Are there any advantages other than the
            faster SAS

            backend to warrant going to these shelves in our
            environment?

            Thanks,

            Jeff

            -- 

            Jeff Cleverley

            Unix Systems Administrator

            4380 Ziegler Road

            Fort Collins, Colorado 80525

            970-288-4611

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