SCPU(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 termos of  dat load , query and reporting during teh wor 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, the numer of of disk I/O request will also will be increased, assuming the same worload 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