Hmm… SATA Really *IS* Slower than Fibre Channel

I (Greg Porter) said in an earlier post that we were using CentOS5 with a Sun Storedge 3511 SATA Array to serve up NFSv4 home directories to Linux clients and SAMBA home directories to Windows users. In benchmarks this setup proved faster. But the stuff hit the fan when the quarter started and the users started pounding on it…

It basically melted. Just quit responding. So even though in benchmarks with bonnie++ doing lots of reads and writes it was faster, a lot of concurrent smaller reads and writes overwhelmed it. So yeah, I should have believed Sun when they said “They are not designed to be used in primary online applications. We scrambled to get back on the fibre channel array as soon as possible.

So if you are attempting to serve up a lot of home directories, don’t use a 3511. There’s probably a reason that Sun doesn’t sell these anymore.

After further testing we discovered that this appears to the typical behavior for this array.  Up to a certain threshold point, it works just fine, fast reads and writes.  But once you cross the threshold, its performance radically degrades, to the point it is basically unusable.


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