Yo Duncan! On Fri, 28 Jun 2013 09:12:24 +0000 (UTC) Duncan <1i5t5.dun...@cox.net> wrote:
> Duncan posted on Fri, 28 Jun 2013 03:36:10 +0000 as excerpted:
>
> I settled on a 4 GiB file. Speeds are power-of-10-based since that's
> what dd reports, unless otherwise stated.
dd is pretty good at testing linear file performance, pretty useless
for testing mysql performance.
> To SSD: peak was upper 250s MB/s over a wide blocksize range of 1 MiB
> >From SSD: peak was lower 480s MB/s, blocksize 32 KiB to 512 KiB
Sounds about right. Your speeds are now so high that small differences
in the SATA controller chip will be bigger than that between some
SSD drives. Use a PCIe/SATA card and your performance will drop from
what you see.
> Spinning rust speeds, single Seagate st9500424as, 7200rpm 2.5" 16MB
Those are pretty old and slow. If you are going to test an HDD against a
newer SSD you should at least test a newer HDD. A new 2TB drive could
get pretty close to your SSD performance in linear tests.
> To rust: upper 70s MB/s, blocksize didn't seem to matter much.
> >From rust: upper 90s MB/s, blocksize upto 4 MiB.
Seems about right, for that drive.
I think your numbers are about right, if your workload is just reading
and writing big linear files. For a MySQL workload there would be a lot
of random reads/writes/seeks and the SSD would really shine.
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
g...@rellim.com Tel:+1(541)382-8588
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