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Perfomance issue IBM 5035 ISCSI 10GbE

  • 1.  Perfomance issue IBM 5035 ISCSI 10GbE

    Posted Thu November 21, 2024 12:07 PM

    Hello,

    we have two IBM 5045 enclosure's with each 12x 3,49 TiB SSDs. 3x VMWare 7.0.3 hosts are connected with 10GbE ethernet iscsi nic's (dac-cable).
    Firmware 8.7.0.1

    We configured this hosts as generic-hosts without chap. We disabled DelayedAck on the esxi hosts. No jumbo frames.

    If we copy big files form one VM to a second VM we see  400-500MB/sec.

    IOMeter and diskspd show 35.000 iops

    But our backups a terrible slow 10-15mb/sec. The storage latency is very high. esxtop show DAVG 184824ms. You can't control the while the backup is runing.

    DAVG => This is the average response time in milliseconds per command being sent to the device.
    KAVG => This is the amount of time the command spends in the VMkernel.

    If we stop the backups the system is working normally.

    Today we stressed the storage and copy a lot of gigabyte from internal storage to ibm and backward. And we se the same issue. VM hang, big davg / kavg vaules and after a some time it works normal.

    We see 100% active time for the hard disk but no read or write:

    The IBM system works in hyperswap mode. The problem exist with single disks too.

    It seeams that the san traffic got a stop signal from the storage

    Please help.

    Thomas



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    Thomas
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