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Virtualizing FS5200 behind an IBM SVC

  • 1.  Virtualizing FS5200 behind an IBM SVC

    Posted Tue July 25, 2023 11:29 AM

    Hello Everyone,

    Looking for some guidance on a setup that I am trying to do. We have an existing IBM SVC which is virtualizing some of the old V7000 and V5000 Storwize boxes. We have recently procured some FS5200 systems and the task is to virtualize them behind the SVC as the other systems. I followed the auto-configuration process that the FS5200 offers and it provisioned a pool for me...but I have some queries on how this setup.

    1. The goal is to use the compression capability of the FS system as they have NVME disks, but the auto configuration tool configured a "Standard Pool" and not DRP ??
    2. Some article says you should have DRP at the top level... OK.. so that means I should create a DRP Pool on the SVC ??
    3. I did create DRP Pool on the SVC and created a Compressed volume in it, but I could see that the system is utilizing SVC's Real Time Compression License...This should not happen as the backend disks are already compression enabled... confused !!!
    4. I further went ahead and deleted the volume... it had around 600GB compressed data.. took around 4 hrs for the deletion to complete (This seemed inline with the mirror sync rate speed of 64MB/s).... is there a reason for this long deletion time... deletion on storwize happens instantly.
    5. Next... although the SVC now reports that the pool is empty.... FS5200 still says it has 600GB usable space.... Not sure why ??   

    Any advice on how this setup should look like would be appreciated.



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    Thanks and Regards,
    Imran
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  • 2.  RE: Virtualizing FS5200 behind an IBM SVC

    Posted Wed July 26, 2023 03:23 AM
      |   view attached

    Dear Imran
    NVMe is the protocol between the controller and the disk and has nothint to do with the functions of the disks. There are FlashDrives, classic storage, and FlashCore Modules (FCM) with buildin HW Compression (and encryption).

    If you will using DRP, all functions will be done on CPU level and will have performanceimpact on the storage. Compression can effectivily be done only one time.
    DRP Pool on SVC level can be defined and causes CPU cycles and all backendrelated compression will not compress data anymore. The second option to do compression is DRP on Backendstorage and the third option (not capabel to disable) is the compression of the FCM

    Please consider that the SVC tries to write big I/Os to the backend. Compression has a litte impact, if the blocksize is small. Increasing the blocksize will increase exponentialy the CPU load of the backend Storage causing immense latency. 

    We hab an issue in the past, where a customer places a Storwize5030 with compression enabled behind a SVC and he gets latencies, that are unaceptable. We changes the Storage to a 5100 with FCMs buildin and the expected performance is back

    When i am doing sizing, i will use traditional Pool on SVC, traditional pool on the FS5200 and use the HW compression on the FCMs. As you have to license the usable (physical) capacity of the backend, it is no more a matter of SVC licenses, if the abckend does compression. So you get the most usable capacity out of the hardware. I have done a presentation last year about selectin which machine. On page 22 ff, there you can see the expected effect of the different setups of a FS5035 machine. Also the difference in Pooldesign brutto vs. netto.

    kind regards
    Martin



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    Martin Haussmann
    SE
    TD SYNNEX
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