Re: SSD + RAID

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От Laszlo Nagy
Тема Re: SSD + RAID
Дата
Msg-id 4AFF62EF.3090201@shopzeus.com
обсуждение исходный текст
Ответ на Re: SSD + RAID  (Robert Haas <robertmhaas@gmail.com>)
Список pgsql-performance
Robert Haas wrote:
> 2009/11/14 Laszlo Nagy <gandalf@shopzeus.com>:
>
>> 32GB is for one table only. This server runs other applications, and you
>> need to leave space for sort memory, shared buffers etc. Buying 128GB memory
>> would solve the problem, maybe... but it is too expensive. And it is not
>> safe. Power out -> data loss.
>>
I'm sorry I though he was talking about keeping the database in memory
with fsync=off. Now I see he was only talking about the OS disk cache.

My server has 24GB RAM, and I cannot easily expand it unless I throw out
some 2GB modules, and buy more 4GB or 8GB modules. But... buying 4x8GB
ECC RAM (+throwing out 4x2GB RAM) is a lot more expensive than buying
some 64GB SSD drives. 95% of the table in question is not modified. Only
read (mostly with index scan). Only 5% is actively updated.

This is why I think, using SSD in my case would be effective.

Sorry for the confusion.

  L


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