none
High latency on StorSimple - without any specific reason? RRS feed

  • Question

  • We use StorSimple as space for W2012R2 file server over iSCSI, it generally works fine, but sometimes, without any specific reason, the I/O host latency jumps from normal (close to 0) up to 2500-3000 ms, together with 'outstanding IOPS' and users complain.

    Checked IOPS and throughput - everything was very low (less than 100 IOPS and 10 MB/s).

    CPU load is constantly high (90%) - but this seems to have no impact (we get good and bad performance with high CPU load).

    Run StorSimple diagnostics - no issues found.

    Any clues?

    Wednesday, March 2, 2016 12:50 AM

Answers

  • This could be due to the local appliance being overloaded or due to the appliance having to tier data out to the cloud to make room for new data. 

    A few possibilities
    * There are spikes in local IO requests during the day. Maybe a machine is running some scripts to copy a bunch of data or do some background task. You could look at the local traffic and see if there is something hogging the IO at the time. 

    * It could be that the backup schedules are too aggressive and overlapping. If you try to backup everything on the appliance at the same time in the middle of the workday, the appliance could be working really hard to do all the backups as well as the host IO. 

    * Typically the appliance should be configured to do do at least one nightly backup for all volumes. This ensures all the daily changes are sent to the cloud during off hours. That can eliminate the appliance having to tier more data out during the day. 

    Wednesday, March 16, 2016 5:06 PM
    Answerer