Yeah, this area is changing very fast!
I agree - choosing carefully is important, as there are still plenty of
older models around that are substantially slower. Also choice of
motherboard chipset can strongly effect overall performance too. The 6
Gbit/s ports on Sandy and Ivy bridge Mobos [1] seem to get close to that
rated performance out of the SSD that I've tested (Crucial m4, Intel
various).
Cheers
Mark
[1] Which I think are actually Intel or Marvell controllers.
On 03/12/12 00:14, Vitalii Tymchyshyn wrote:
Well, it seems that my data can be outdated, sorry for that. I've just
checked performance numbers on Tom's hardware and it seems that best sad
really do 500 MB/s. Some others do 100. So, I'd say one must choose wisely
(as always :-) ).
Best regards,
Vitalii Tymchyshyn
1 груд. 2012 00:43, "Mark Kirkwood" <mark.kirkwood@xxxxxxxxxxxxxxx> напис.
Hmm - not strictly true as stated: 1 SSD will typically do 500MB/s
sequential read/write. 1 HDD will be lucky to get a 1/3 that.
We are looking at replacing 4 to 6 disk RAID10 arrays of HDD with a RAID1
pair of SSD, as they perform about the same for sequential work and vastly
better at random. Plus they only use 2x 2.5" slots (or, ahem 2x PCIe
sockets), so allow smaller form factor servers and save on power and
cooling.
Cheers
Mark
On 30/11/12 23:07, Vitalii Tymchyshyn wrote:
Oh, yes. I don't imagine DB server without RAID+BBU :)
When there is no BBU, SSD can be handy.
But you know, SSD is worse in linear read/write than HDD.
Best regards, Vitalii Tymchyshyn
2012/11/30 Mark Kirkwood <mark.kirkwood@xxxxxxxxxxxxxxx
<mailto:mark.kirkwood@**catalyst.net.nz <mark.kirkwood@xxxxxxxxxxxxxxx>>>
Most modern SSD are much faster for fsync type operations than a
spinning disk - similar performance to spinning disk + writeback
raid controller + battery.
However as you mention, they are great at random IO too, so Niels,
it might be worth putting your postgres logs *and* data on the SSDs
and retesting.
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