Re: Mount database on RAM disk? - Mailing list pgsql-performance

From Merlin Moncure
Subject Re: Mount database on RAM disk?
Date
Msg-id 6EE64EF3AB31D5448D0007DD34EEB3415C2CFE@Herge.rcsinc.local
Whole thread Raw
In response to Mount database on RAM disk?  (Stuart Bishop <stuart@stuartbishop.net>)
Responses Re: Mount database on RAM disk?  (Alex Stapleton <alexs@advfn.com>)
List 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

pgsql-performance by date:

Previous
From: Tom Lane
Date:
Subject: Re: cost-based vacuum
Next
From: Jochem van Dieten
Date:
Subject: Re: Select performance vs. mssql