[mythtv-users] SSD for speed up FE/BE

[Ronald Frazier]

On Wed, Jun 6, 2012 at 5:52 PM, Josu Lazkano <josu.lazkano at gmail.com> wrote:
> Hello all,
>
> I am thinking on buy a little SSD drive to speed up my Nvidia ION Atom
> FE/BE system. Actually I host MySQL data directory on 2.5 HDD
> (5400rpm) EXT4 disk. I have some questions about SSD setup.
>
> 1. Which is the best option to host MySQL datadir? EXT3? EXT4? XFS?
> Mount options?
> 2. Must I host other files on the SSD disk? channel icons? logs?
>
> I am planning on buy a little disk, maybe 4 or 8GB. I will appreciate
> any help, thanks and best regards.

I started a thread on my SSD upgrade earlier this year, and a lot was
discussed there. Check it out in the archives.

My biggest concern is what sort of "SSD" are you planning to use? When
you say 4-8GB, I don't think they make real SSDs in that size, so you
I'm assuming you mean to get a flash drive (compact flash, SD, memory
stick, etc). If so, my biggest concerns with those would be

1) performance - even though access times should be good, sequential
access will be considerably slower than a HDD. It seems like most
flash cards are limited to 20-30 MB/sec unless you pay more for a high
end one. Overall you'll probably still be better off than an HDD, but
I can't say for certain how much better.

2) longevity - this is even more important. SSDs are designed to
handle tons of writes before they wear out. On the other hand, I've
heard a lot of reports that flash drives wear out much more quickly.
If you can minimize writes to the drive, you can greatly reduce this
issue. With a myth system, your 2 biggest culprits are going to be
logging and mysql. In my other thread (mentioned above) I talked a bit
about this issue and what I found. Specifically, one of the biggest
issues was mysql temporary tables, which are used by myth when it runs
the scheduler. Even with the better longevity of a real SSD, writes
from the scheduler were going to blow through the rated life of the
drive in just a couple years. By moving those temporary table writes
to RAM, writes to the SSD were drastically reduced.


-- 
Ron Frazier