Topic
11 replies Latest Post - ‏2013-05-23T15:43:04Z by tuscani
tuscani
tuscani
16 Posts
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Pinned topic Dynamic Disk Pool

‏2013-05-10T00:25:36Z |

We have a DS3524 with a 16 drive DPP (RAID6). We are planning to add another 8 drives to the 3524 and then a fully populated expansion enclosure. Would we add the new 32 disks to the existing pool or it is best to break it up? Thanks!

 

 

  • AndersLorensen
    AndersLorensen
    139 Posts
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    Re: Dynamic Disk Pool

    ‏2013-05-21T10:36:31Z  in response to tuscani

    There is a limit on the DS35xx that you can only add 12 disks at a time to a disk pool. So you'll have to do the add operation a few times to get there.

    There is no limit on how many disks you can have in a pool. I have a customer who have 192 disks (all 1 TB SATA disks) in the same pool on a single DS3524.

    --

    Anders

    • tuscani
      tuscani
      16 Posts
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      Re: Dynamic Disk Pool

      ‏2013-05-21T13:32:21Z  in response to AndersLorensen

      Thanks for the reply! I suppose one really big pool is preferred.. curious.. how do they setup logical drives and how mnay disks could fail before data loss?

       

       

      • AndersLorensen
        AndersLorensen
        139 Posts
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        Re: Dynamic Disk Pool

        ‏2013-05-21T14:03:31Z  in response to tuscani

        One big pool means you dont have to do any "load balancing" between pools. All LUN's get the performance of all the disks. The downside is that one server can steal all the performance if it wants to.

         

        As for data loss, its very very unlikely. Each Raidset in the pool can manage to loose 2 disks. So you need 3 disks to fail at the same time to get data loss. The pool contains alot of those Raid6 raidsets, so its not more dangerous to have 1 big pool, over 2 pools, as you'll have the same number of raid sets.

        The customer uses his 192 disks for a large Exchange solution running on VMWare. They actually have two of those 192-disk DS3524's, as the whole solution is mirrored to a second site. (mirroring, using Exchange DAG replkation).

        The biggest issue with the solution is the VMWare limitation that it cannot handle more than 32 TB capacity open on 1 ESX host! But thats a different subject!

         

        --

        Anders

        • tuscani
          tuscani
          16 Posts
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          Re: Dynamic Disk Pool

          ‏2013-05-21T14:23:13Z  in response to AndersLorensen

          Cool... right now we have a 3524 with a single pool of 16x900gb SAS.. I only have about 8TB useable which I thought was weird though since only two disks are preservation.

          We plan to add eight more disks to the 3524, puchase another enclosure and fully populate with 32 more disks. Adding all the the existing pool. We are using VMware ESXi 4.1 but will be moving to Server 2012 Hyper-V.  Right now LUNS are carved out 1TB each.

           

           

          • AndersLorensen
            AndersLorensen
            139 Posts
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            Re: Dynamic Disk Pool

            ‏2013-05-21T14:33:50Z  in response to tuscani

            Hot spare disks are build into the pool as well. Default, if I remember correct is 4 hotspare disks.

            So you have 16 disks. 2 disks go to parity. 4 as hotspares. = 10 disks usable.

            900 * 10 = 9 TB or about 8,1 TiB Usable. (The storage manager displays in TiB, even though it writes TB)

            If you only have 16 disks (or even when you land at 48 disks) you might want to lower that hotspare number - its easy to alter.

             

            --

            Anders

            • tuscani
              tuscani
              16 Posts
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              Re: Dynamic Disk Pool

              ‏2013-05-21T14:51:46Z  in response to AndersLorensen

              Thanks! I wasn't aware hot spares were also included! I am a server guy but have taken on storage recently as you can prob tell. Zoning all this was fun a few weeks ago consideringI have never done it :)

              So when we add the 32 new disks we can expect all of that to be useable right? I am thinking I will drop down to two hot spares when all said and done.

              Any gotchas when adding disks or enclosures?

              • AndersLorensen
                AndersLorensen
                139 Posts
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                Re: Dynamic Disk Pool

                ‏2013-05-22T10:47:23Z  in response to tuscani

                When adding a new shelf and new disks, consider this:

                Firmware upgrade of shelfs (ESM) and disks cannot be done online, so do it before you put them to use! That means, you attach the stuff, then firmware update it, and lastly, add the disks to the pool. Once the disks are in the pool, you wont upgrade ESM/HDD firmware without downtime.

                Attaching one shelf is a walk in the part! More than 1, and you want to read the manual on how to cable it correct.

                As for Zoning, hope you got it right! I've seen many strange zoning configurations in my life. Everything from Alias, port and wwn zoning in one big mix, to "add all WWN's to an alias, and a zone with 1 alias" - Which all works, but is not supportet nor easy to work with.

                When you add the disks, new raid sets will be created, so some of the disks will be used for parity.

                 

                --

                Anders

                • tuscani
                  tuscani
                  16 Posts
                  ACCEPTED ANSWER

                  Re: Dynamic Disk Pool

                  ‏2013-05-22T15:42:06Z  in response to AndersLorensen

                  I always update the FW prior to install..

                  Here is how I did the zoning:

                   

                  ABS-FC-SW-A

                  Aliases

                  ABS_SAN_CTRL_A_PORT3 (one member.. WWPN 20:3e:00:80:e5:24:a5:ea)
                  ABS_SAN_CTRL_B_PORT3 (one member.. WWPN 20:3f:00:80:e5:24:a5:ea)
                  LOKI_PORT1 (one member.. WWPN 21:00:00:24:ff:4c:5f:68)
                  ZEUS_PORT1 (one member.. WWPN 21:00:00:24:ff:4c:62:c6)

                  Zones

                  CTRLAPORT3_LOKIPORT1_ZONE
                    -ABS_SAN_CTRL_A_PORT3(1 Members)
                    -LOKI_PORT1(1 Members)

                  CTRLAPORT3_ZEUSPORT1_ZONE
                    -ABS_SAN_CTRL_A_PORT3(1 Members)
                    -ZEUS_PORT1(1 Members)

                  CTRLBPORT3_LOKIPORT1_ZONE
                    -ABS_SAN_CTRL_B_PORT3(1 Members)
                    -LOKI_PORT1(1 Members)

                  CTRLBPORT3_ZEUSPORT1_ZONE
                    -ABS_SAN_CTRL_B_PORT3(1 Members)
                    -ZEUS_PORT1(1 Members)

                  Zone Config

                  TeamAbsolute
                    -CTRLAPORT3_LOKIPORT1_ZONE
                    -CTRLAPORT3_ZEUSPORT1_ZONE
                    -CTRLBPORT3_LOKIPORT1_ZONE
                    -CTRLBPORT3_ZEUSPORT1_ZONE

                   

                  ABS-FC-SW-B

                  Aliases

                  ABS_SAN_CTRL_A_PORT5 (one member.. WWPN 20:5e:00:80:e5:24:a5:ea)
                  ABS_SAN_CTRL_B_PORT5 (one member.. WWPN 20:5f:00:80:e5:24:a5:ea)
                  LOKI_PORT2 (one member.. WWPN 21:00:00:24:ff:4c:5f:69)
                  ZEUS_PORT2 (one member.. WWPN 21:00:00:24:ff:4c:62:c7)

                  Zones

                  CTRLAPORT5_LOKIPORT2_ZONE
                    -ABS_SAN_CTRL_A_PORT5(1 Members)
                    -LOKI_PORT2(1 Members)

                  CTRLAPORT5_ZEUSPORT2_ZONE
                    -ABS_SAN_CTRL_A_PORT5(1 Members)
                    -ZEUS_PORT2(1 Members)

                  CTRLBPORT5_LOKIPORT2_ZONE
                    -ABS_SAN_CTRL_B_PORT5(1 Members)
                    -LOKI_PORT2(1 Members)

                  CTRLBPORT5_ZEUSPORT2_ZONE
                    -ABS_SAN_CTRL_B_PORT5(1 Members)
                    -ZEUS_PORT2(1 Members)

                  Zone Config

                  ABS
                    -CTRLAPORT5_LOKIPORT2_ZONE
                    -CTRLAPORT5_ZEUSPORT2_ZONE
                    -CTRLBPORT5_LOKIPORT2_ZONE
                    -CTRLBPORT5_ZEUSPORT2_ZONE

                  • AndersLorensen
                    AndersLorensen
                    139 Posts
                    ACCEPTED ANSWER

                    Re: Dynamic Disk Pool

                    ‏2013-05-23T07:48:39Z  in response to tuscani

                    Looks great. You can make it simplier by having 1 zone per server per fabric, with 3 aliases in - 1 for each controller, and 1 for the server hba. You would end up with half as many zones.

                    Previous it was not supported, having both storage controllers in the same zone.(mainly older DS4xxx boxes) But it is now a supported way of doing it. Some storage systems even requires it. (Storwize for example, as it uses fiber as a backup communications channel between the controllers if the midplane behaves badly.)

                    --

                    Anders

                    • tuscani
                      tuscani
                      16 Posts
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                      Re: Dynamic Disk Pool

                      ‏2013-05-23T15:43:04Z  in response to AndersLorensen

                      Good to know! Thanks for reviewing.

                      Also, check ed and it shows 0 hot spare disks in use.. also found this in the help docs:

                       

                      NOTE
                      Hot spare drives are not used in disk pools.

                       

  • tuscani
    tuscani
    16 Posts
    ACCEPTED ANSWER

    Re: Dynamic Disk Pool

    ‏2013-05-21T15:07:58Z  in response to tuscani

    Also, check ed and it shows 0 hot spare disks in use.. also found this in the help docs:

     

    NOTE  
    Hot spare drives are not used in disk pools.