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5 replies Latest Post - ‏2013-01-29T08:40:13Z by SystemAdmin
dsmithpdx
dsmithpdx
6 Posts
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Pinned topic DS3512 + Two EXP3512s: Best Configuration?

‏2012-10-11T20:45:57Z |
Hi all,

We have had a DS3512 with 12 450GB 15k drives in it for a couple of years now. Those drives are configured in a RAID10, with two logical drives. We are running VMware ESXi 5.0, which is currently configured with two LUNs/datastores that correspond to the two logical drives on the DS. We have two IBM x3650 M2 hosts using that storage.

Today, we added two EXP3512 units to the DS3512, fully populated with 24 450GB 15k drives (12 in each). My original thought was to create two additional RAID10 sets, each with two logical drives, to mirror the existing config. However, now I'm wondering if there is perhaps a better way to do it.

Should I just expand the existing RAID10 array to utilize the new drives, and then expand the LUNs in VMware (can that even be done?)? Or perhaps create one additional RAID10 set using all 24 of the new drives, and then create two logical drives in that array?

Originally, we had to create two LUNs, as ESXi 4.1 had a max supported datastore size of 2TB. In ESXi 5.0, that is no longer the case, so we have more options.

In addition to the new EXP3512 units, we are also installing two additional x3650 M4 hosts, so we will have a total of four VMware hosts utilizing this storage. The newly expanded cluster will primarily be running a large MS SQL server, as well as multiple MS Windows Terminal Servers. Obviously, I'm looking to maximize the performance of the SQL server first and foremost.

Any advice would be greatly appreciated.
Updated on 2013-01-29T08:40:13Z at 2013-01-29T08:40:13Z by SystemAdmin
  • Berniebgbb
    Berniebgbb
    83 Posts
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    Re: DS3512 + Two EXP3512s: Best Configuration?

    ‏2012-10-12T09:58:51Z  in response to dsmithpdx
    You could update to the latest firmware version and run Storage Pooling with Thin provisioned volumes.
    Then let the DS manage I/O distribution evenly across the disks, takes allot of hassle out of the configuration.

    If you have time it would be worth doing some performance comparisons.

    The best info on the technology at the moment can be found in the Help section of the latest storage manager software, so save the trouble and install the latest version to learn more. then you will be ready to update your firmware.....Next up will be "Auto Tiering" for the pooling to SSD, it is just a matter of time.

    Bernie
    • dsmithpdx
      dsmithpdx
      6 Posts
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      Re: DS3512 + Two EXP3512s: Best Configuration?

      ‏2012-10-12T17:37:53Z  in response to Berniebgbb
      Thanks. We are running the latest firmware (7.83), so we are going to go with Storage Pooling and Thin provisioned drives. We are going to create two disk pools of 12 disks each, and then create two logical drives in each pool (four logical drives total).

      In going through the wizard, I'm a bit confused by the "maximum expansion capacity" setting. Is that literally the maximum size to which the logical drive can grow? If so, why is it defaulting to half the size of the actual logical drive? I want VMware to be able to use the entire capacity of the logical drives, obviously. Am I missing something? The documentation is lacking in this department. Any advice?
      • Berniebgbb
        Berniebgbb
        83 Posts
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        Re: DS3512 + Two EXP3512s: Best Configuration?

        ‏2012-10-15T04:16:07Z  in response to dsmithpdx
        Personally I would head toward a single pool configuration for the 24 drives and simply increase preservation capacity to more "disks" (but they aren't really, its capacity).From what I have seen onsite, the dynamic IO distribution in the pool is VERY good. Put all disks in the pool to get better IO balancing across the 24 disks.

        The "maximum expansion capacity" sets the maximum "physical" disk space the DS3500 will allow the thin provisioned volume to consume before it STOP's IO to keep it from consuming anymore space. This 50% setting is ridiculous, as an example if you create a 1TB thin volume all IO will stop to that volume when it is @ 500GB used.....

        You will need to go in an modify this setting to allow capacity to grow....resume normal IO.

        I would recommend you set this to 80 -100% and make sure you set your Pool threshold warning at appropriate levels and make sure you get E-mail alerts.
        • dsmithpdx
          dsmithpdx
          6 Posts
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          Re: DS3512 + Two EXP3512s: Best Configuration?

          ‏2012-10-15T04:23:32Z  in response to Berniebgbb
          Sounds reasonable to me. My boss thinks we should create two pools of 12 disks each, and then place the SQL database load on one of the pools to keep the I/O separate from the VMs running on the other pool. Does that even make sense??? Is there any practical reason to create two pools rather than one? Any potential performance to be gained?
          • SystemAdmin
            SystemAdmin
            4779 Posts
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            Re: DS3512 + Two EXP3512s: Best Configuration?

            ‏2013-01-29T08:40:13Z  in response to dsmithpdx
            Sorry to butt in on this thread, but one of the questions you asked was pertinent to me:

            "expand the LUNs in VMware (can that even be done?)? "

            Did you find out if this was possible on a DS3512? I've posted the same question: https://www.ibm.com/developerworks/forums/thread.jspa?threadID=469443