Message-ID: <50BBE57B.8010803@catalyst.net.nz>
Date: Mon, 03 Dec 2012 12:34:19 +1300
From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
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To: Vitalii Tymchyshyn <tivv00@gmail.com>
CC: Kevin Grittner <kgrittn@mail.com>, =?UTF-8?B?TmllbHMgS3Jpc3RpYW4gU2No?=
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	sthomas@optionshouse.com, Willem Leenen <willem_leenen@hotmail.com>
Subject: Re: Optimize update query
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Yeah, this area is changing very fast!

I agree - choosing carefully is important, as there are still plenty of=20
older models around that are substantially slower. Also choice of=20
motherboard chipset can strongly effect overall performance too. The 6=20
Gbit/s ports on Sandy and Ivy bridge Mobos [1] seem to get close to that=20
rated performance out of the SSD that I've tested (Crucial m4, Intel=20
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 Well, it seems that my data can be outdated, sorry for that.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 =D0=B3=D1=80=D1=83=D0=B4. 2012 00:43, "Mark Kirkwood" <mark.kirkwood@ca=
talyst.net.nz> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81.
>
>> 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 vast=
ly
>> 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@catalyst.net.nz
>>> <mailto:mark.kirkwood@**catalyst.net.nz <mark.kirkwood@catalyst.net.nz>=
>>
>>>
>>>      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.
>>>
>>>


--=20
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