| From: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
|---|---|
| To: | Greg Smith <greg(at)2ndquadrant(dot)com> |
| Cc: | Greg Spiegelberg <gspiegelberg(at)gmail(dot)com>, Yeb Havinga <yebhavinga(at)gmail(dot)com>, Matthew Wakeling <matthew(at)flymine(dot)org>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Testing Sandforce SSD |
| Date: | 2010-07-26 19:47:14 |
| Message-ID: | AANLkTine0bsX_dvQgncDn600Vmt4KoUb3vSL3LW9qocB@mail.gmail.com |
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| Lists: | pgsql-performance |
On Mon, Jul 26, 2010 at 12:40 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> Greg Spiegelberg wrote:
>>
>> Speaking of the layers in-between, has this test been done with the ext3
>> journal on a different device? Maybe the purpose is wrong for the SSD. Use
>> the SSD for the ext3 journal and the spindled drives for filesystem?
>
> The main disk bottleneck on PostgreSQL databases are the random seeks for
> reading and writing to the main data blocks. The journal information is
> practically noise in comparison--it barely matters because it's so much less
> difficult to keep up with. This is why I don't really find ext2 interesting
> either.
Note that SSDs aren't usually real fast at large sequential writes
though, so it might be worth putting pg_xlog on a spinning pair in a
mirror and seeing how much, if any, the SSD drive speeds up when not
having to do pg_xlog.
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