From: | Vitalii Tymchyshyn <tivv00(at)gmail(dot)com> |
---|---|
To: | Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> |
Cc: | Kevin Grittner <kgrittn(at)mail(dot)com>, Niels Kristian Schjødt <nielskristian(at)autouncle(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>, sthomas(at)optionshouse(dot)com, Willem Leenen <willem_leenen(at)hotmail(dot)com> |
Subject: | Re: Optimize update query |
Date: | 2012-12-02 11:14:24 |
Message-ID: | CABWW-d0DLno85J+JqUqEkodmD1uORtsAPvSbCUJ_kH2Xvs82tA@mail.gmail.com |
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Lists: | pgsql-performance |
Well, it seems that my data can be outdated, sorry for that.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(dot)kirkwood(at)catalyst(dot)net(dot)nz> 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(dot)kirkwood(at)catalyst(dot)net(dot)nz
>> <mailto:mark(dot)kirkwood(at)**catalyst(dot)net(dot)nz <mark(dot)kirkwood(at)catalyst(dot)net(dot)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.
>>
>>
>
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