topic Re: Performance with Embedded Array Controller in ProLiant Servers (ML,DL,SL)

Performance with Embedded Array Controller

tdeneau1 — Fri, 23 Sep 2016 19:22:22 GMT

I inherited some DL360 systems which had P440ar Smart Array controller to which the OS drive and 7 data drives were attached. I wanted to experiment with the embedded controller instead so I moved the drives there. (the P440ar was still in the system just nothing connected).

When I measured dd performance using reads with iflag=direct, performance was as I expected, in fact was similar to using the P440ar in HBA mode. However, when I tried dd writes with oflag=direct, performance was terrible (less than 10 MB/s).

Is there some configuration issue I am missing?

Re: Performance with Embedded Array Controller

Edwin Eppel — Tue, 27 Sep 2016 19:37:38 GMT

The embedded controller has no cache while the P440ar should have a write-behind cache. That's going to have some impact on performance.

Re: Performance with Embedded Array Controller

tdeneau1 — Tue, 27 Sep 2016 22:30:06 GMT

The test I was using was running

dd of=/dev/sdb2 if=/dev/zero oflag=direct bs=64K count=10000

Since I am using oflag=direct, I would have thought that would take the cache out of the picture. On other no-cache controllers on other systems I have seen approximately 140 MB/sec with these same drives

Re: Performance with Embedded Array Controller

Dennis Handly — Sat, 01 Oct 2016 21:37:26 GMT

> I would have thought that would take the cache out of the picture.

That's probably just the OS cache.