[mythtv-users] Sony Vaio, perhaps?

[Travis Tabbal]

On Thu, Apr 2, 2009 at 11:07 AM, Marc Randolph <mrand at pobox.com> wrote:

> I do care, but haven't seen a problem.  Have you?  If so, please
> elaborate!  I'll take it for face value that it does some ugly SQL
> accessing during scheduling.  What does that translate to in terms of
> system resources?  Is it enough to swamp an IDE drive by itself, or do
> you only have problems on IDE when it is doing scheduling while
> simultaneously trying to record 4 shows at the same time?  When you
> move to SATA, what does the utilization drop to?
>


I have. My SATA drive, 500GB Seagate, worked fine for a while. But after
about a year, I started getting breakups in the recordings. I checked the
signal and tuner and discovered that it was fine. So I suspected I/O issues.
Hacking the backend to remove the syncs and increasing the buffers helped a
lot, but I still had some issues. So I grabbed an old 80GB drive I had
floating around, dropped it in, and copied all the OS data over to it. A
little work with grub and the BIOS, and I'm booting from the new drive. I
kept the old drive in for recordings only. I have yet to see a breakup
since. I am now convinced. Keeping the OS and database on a separate spindle
is worth the bother. I'll probably do USB flash sticks in the future as they
are cheap and big enough for what I need.

I didn't know how to log drive activity levels, but CPU levels are about
5-10% while recording. Makes sense as all the backend is doing is reading
and writing data. It isn't doing any processing. I also tried disabling all
jobs, no commflags or transcodes running. That also helped, but not enough.
Now I can run jobs while the main backend is recording and it works fine.

The 80GB drive is a 5400RPM drive. I can tell it's slower during the boot,
but once the system is running, it's not noticeable. I doubt it's the data
rate really, it's the random I/Os that are killing it. The seek time + the
transfer time is just enough to cause issues. Interestingly, even SSDs have
had issues with random I/O and that's what most disk activity is on a modern
system.
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