[mythtv-users] SSD disk for DB

Gary Buhrmaster gary.buhrmaster at gmail.com
Tue Oct 9 02:33:12 UTC 2012


On Mon, Oct 8, 2012 at 7:08 PM, jedi <jedi at mishnet.org> wrote:
....
>    SSD's are great for random IO which is what you tend to hit hard with
> most databases.

Random *read* I/O (because the seek time is closer to zero).
Whether they are great for *write* I/O depends on their designs
(the seek time is still closer to zero, but (re)writing blocks
may take some time in some designs, and databases tend
to insist on durable writes (data committed to "disk") in order
to insure ACID compliance).  As with much else, your mileage
will vary.

I will note that for most MythTV users, a well tuned cache
essentially eliminates all (read) I/O too (we are not talking
about a one PB database, more like a few hundred megabytes,
which can fit in memory cache).  Unfortunately, the mysql
defaults in most distros really suck, so that putting the database
on SSD looks to be a great win.  There are some good (initial)
suggestions on the MythTV wiki regarding mysql tuning.

Gary


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