AIX

AIX

Connect with fellow AIX users and experts to gain knowledge, share insights, and solve problems.


#Power
 View Only

  • 1.  Same workload producing different IOPS in system with less LUNS?

    Posted Wed July 27, 2011 10:58 PM

    Originally posted by: SystemAdmin


    Greetings all,

    I would like to request the help of experts regarding an analysis that we are currently doing.

    We have two AIX LPARs one with 13 LUNs and the other with 37 LUNs. There are some differences in the underlying storage subsystem too.

    When loading the two LPARs with the same workload (we believe it is the same!), we can see that even though the CPUs are comparable, however the IOPS are significantly different. The system with 13 LUNs shows much fewer IOPS as compared to the system with 37 LUNS.

    Is the above expected or may be we are running the load test wrong?

    If the above is expected, what can this be attributed to assuming that the workload is the same.

    Thanks in advance for your analysis!

    Sabrang
    #AIX-Forum


  • 2.  Re: Same workload producing different IOPS in system with less LUNS?

    Posted Wed July 27, 2011 11:35 PM

    Originally posted by: SystemAdmin


    1. IOPS = io operations per second , agreed?
    2. How do you measure IOPS?
    #AIX-Forum


  • 3.  Re: Same workload producing different IOPS in system with less LUNS?

    Posted Thu July 28, 2011 01:31 AM

    Originally posted by: SystemAdmin


    We have NMON running on the LPARs that capture disk transfers per second which is same as tps value by vmstat.
    #AIX-Forum


  • 4.  Re: Same workload producing different IOPS in system with less LUNS?

    Posted Wed August 03, 2011 06:30 AM

    Originally posted by: Dave7


    The fact that more LUNs, if the storage they rely on provides more spindles, produce more IOPS seems logical.

    If they provide the same number of spindles, then one could argue that more physical devices presented to the host provide more IO queues, hence more iops in the end.

    You might need to look at other metrics to understand what's going on : queue lenghts, wait time, service time and so on.
    #AIX-Forum


  • 5.  Re: Same workload producing different IOPS in system with less LUNS?

    Posted Fri August 05, 2011 07:19 AM

    Originally posted by: MarkTaylor


    Are you comparing apples with apples ? are both sets of LUNs cut from the same make/model of disk unit, are the carved up in exactly the same way ? how many spindles for each LUN ? same number of FC cards, FC settings the same .. layout of the data the same ? I am guessing probably not in most of the above ..

    Rgds
    Mark Taylor
    #AIX-Forum


Related Content