[CentOS] Centos/Linux Disk Caching, might be OT in some ways
christopher.chan at bradbury.edu.hk
Tue Jan 26 00:19:59 UTC 2010
Noob Centos Admin wrote:
>> If you want a fast database forget about file system caching,
>> use Direct I/O and put your memory to better use - application
>> level caching.
> The web application is written in PHP and runs off MySQL and/or
> Postgresql. So I don't think I can access the raw disk data directly,
> nor do I think it would be safe since that bypasses the DBMS's checks.
Which is it? mysql or postgresql or both? Have you actually determined
that i/o is in fact the bottleneck?
Is the webapp maintaining persistent connections to mysql or is it
continually connecting and disconnecting? mysql sucks big time if you
have a good few hundred connections being setup and torn down all the time.
Are complicated relationships being stored in postgresql and not in
mysql? I do not know how things are now but mysql has a history of only
being good for simple selects.
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