Re: Hardware vs Software RAID
От | Matthew Wakeling |
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Тема | Re: Hardware vs Software RAID |
Дата | |
Msg-id | Pine.LNX.4.64.0806251355090.4085@aragorn.flymine.org обсуждение исходный текст |
Ответ на | Re: Hardware vs Software RAID ("Merlin Moncure" <mmoncure@gmail.com>) |
Ответы |
Re: Hardware vs Software RAID
Re: Hardware vs Software RAID |
Список | pgsql-performance |
On Wed, 25 Jun 2008, Merlin Moncure wrote: >> Has anyone done some benchmarks between hardware RAID vs Linux MD software >> RAID? > > I have here: > http://merlinmoncure.blogspot.com/2007/08/following-are-results-of-our-testing-of.html > > The upshot is I don't really see a difference in performance. The main difference is that you can get hardware RAID with battery-backed-up cache, which means small writes will be much quicker than software RAID. Postgres does a lot of small writes under some use cases. Without a BBU cache, it is sensible to put the transaction logs on a separate disc system to the main database, to make the transaction log writes fast (due to no seeking on those discs). However, with a BBU cache, that advantage is irrelevant, as the cache will absorb the writes. However, not all hardware RAID will have such a battery-backed-up cache, and those that do tend to have a hefty price tag. Matthew -- $ rm core Segmentation Fault (core dumped)
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