SAP IQ CPU(core) to disk I/O ratio

[jmtorres]

Good Day,

Question regarding CPU to disk I/O relation:

1) Initally  we had  two SAP IQ 12.7 instances  runniing on a Linux x64 Red Hat 5.5 machine  with 16 cores / 256Gb RAM

2) Now we  moved to SAP Iq 15.4 on the same macine but leaving just this one instance with same # of cores / RAM available 

This instance is heavily used  in terms of  data load , query and reporting during the day.

Regarding to  CPU to  disk I/O ratio, is it valid or  not  to assume the follwing:

If we bumped up the  number of cores( now 16 available to IQ), the number of of disk I/O request will also will be increased, assuming the same workload and number of users connected?

There is an old  EMC Symmetrix storage involved here , which wasn't upgraded

Thank you

Regards

[markmumy · Accepted solution]

With IQ 15.4, a rough sizing that I use is 25-50 MB/sec of IO needed per core.  With IQ 16 that gets increased even higher.  If you have a heavy workload, then I would assume around 50 MB/sec.  In today's disk world, a disk can sustain about 25 MB/sec of random IO, at best.  This takes us to needing about 2 disks per core on the system.  If you find that main and temp are both being used quite a bit then I would recommend having 2 disks per core per storage type (main, temp).

Mark

[jmtorres · Accepted solution]

Thank you Mark,

But regarding to CPU and disk relationship , is it true to state that if we have more cores/cpus available to IQ, then we'll need more disk I/O bandwidth due to the fact that we have more processing capabilities?

Regards

JM

[markmumy · Accepted solution]

Yes, generally.  With more cores, IQ can then split the job into more parallel streams.  Assuming that the data is on disk, that means more streams need more data from disk and thus an increased IO infrastructure.  Or rather, as we increase cores we will likely need to increase storage IO capacity.

Mark

[jmtorres · Accepted solution]

Mark,

Thank you very much!!

Regards

Jose Miguel