Host I/O Queue Depth with XtremIO and SLOB Session Count. A Granular Look.

Datetime:2016-08-23 04:05:35         Topic: SQL          Share        Original >>
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In my recent post about aggregate host I/O queue depth I shared both 100% SQL SELECT and 20% SQL UPDATE test results (SLOB) at varying LUN (ASM disk) counts. The LUNs mapped to XtremIO volumes but the assertions in that post were really applicable in most All-Flash Array situations.

I received quite a bit of email from readers about the granularity of session counts shown in the charts in that post. Overwhelmingly, folks asked to see more granular data. It so happens that the charts in that post were a mere snippet of the test suite results so I charted the full data set and am posting them here.

Figures 1 and 2 below show 1,2,4,8 and 16 host LUN results charted from 1 to 450 sessions for the read-only SLOB test and then 1 to 250 sessions for the 20% SQL UPDATE results. Remember that the sessions are zero think-time in this testing, therefore, IOPS are a direct reflection of latency and in this case latency is majority attributed to host queueing as I explained inthe prior post.

The prime message in this data is the Total IOPS values demonstrated at even low host LUN counts and, as such, it makes little sense to create complex ASM disk groups (consisting of large numbers of host LUNs mapped to All-Flash Array storage like XtremIO). Unless, that is, you manage one of the very few production databases that demands IOPS above 100,000. I know these databases exist, but there aren’t as many of them as some might think. High IOPS-capable platforms like XtremIO are generally used for consolidation.

If you click on the image you can get the full-size chart.


Figure 1

Figure 2


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