| From: | Ragnar Kjørstad <postgres(at)ragnark(dot)vestdata(dot)no> |
|---|---|
| To: | Fred Moyer <fred(at)digicamp(dot)com> |
| Cc: | Peter Eisentraut <peter_e(at)gmx(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-admin <pgsql-admin(at)postgresql(dot)org> |
| Subject: | Re: databases and RAID ... |
| Date: | 2002-05-25 20:01:19 |
| Message-ID: | 20020525220119.A32683@vestdata.no |
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| Lists: | pgsql-admin |
On Sat, May 25, 2002 at 12:45:12PM -0700, Fred Moyer wrote:
> Performance (fastest->slowest)
> hardware raid -> software raid
> raid 0 -> 10 -> 1 -> 5
> Redundancy (most -> least)
> hardware raid -> software raid
> 10, 1 -> 5 -> 0
It's really not possible to compare RAID-levels independent from what
the system is beeing used for. E.g. lots of seeks vs continous access,
read-intensive vs write-intensive, how many simultanious accesses and
so on.
E.g. RAID 1 / 10 can easily be as fast, or faster than RAID 0 for read
intensive work.
RAID 5 has a very high penality when doing small writes, but the effect
can be reduced by good RAID-controllers with lots of battery-backed
cached.
For a typical database-application I would agree with your statement
except that RAID 1 is probably faster than RAID 10.
--
Ragnar Kjorstad
Big Storage
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