From: | "Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com> |
---|---|
To: | <josh(at)agliodbs(dot)com> |
Cc: | "Stuart Bishop" <stuart(at)stuartbishop(dot)net>, <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Mount database on RAM disk? |
Date: | 2005-07-08 19:21:21 |
Message-ID: | 6EE64EF3AB31D5448D0007DD34EEB3415C2CFE@Herge.rcsinc.local |
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Lists: | pgsql-performance |
> Stuart,
>
> > I'm putting together a road map on how our systems can scale as our
load
> > increases. As part of this, I need to look into setting up some fast
> > read only mirrors of our database. We should have more than enough
RAM
> > to fit everything into memory. I would like to find out if I could
> > expect better performance by mounting the database from a RAM disk,
or
> > if I would be better off keeping that RAM free and increasing the
> > effective_cache_size appropriately.
>
> If you're accessing a dedicated, read-only system with a database
small
> enough to fit in RAM, it'll all be cached there anyway, at least on
Linux
> and BSD. You won't be gaining anything by creating a ramdisk.
ditto windows.
Files cached in memory are slower than reading straight from memory but
not nearly enough to justify reserving memory for your use. In other
words, your O/S is a machine with years and years of engineering
designed best how to dole memory out to caching and various processes.
Why second guess it?
Merlin
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