[mythtv-users] Odd i/o issues

[Michael D. O'Brien]

In the last week I've upgraded my back and frontends to Ubuntu 8.10 and the
newest myth-fixes.  Last night, I noticed that the show I was viewing was
pausing every few seconds, rendering it nearly unwatchable.  I knew the
backend was recording a few other shows and the frontends hadn't shown this
behavior while the backend was idle earlier that day, so I did some looking
around:

-top on the backend and frontend showed plently of available memory and idle
cpu
-it's not a network issue, the maximum usage in iftop on the frontend looked
to be about 12mbps (out of 100) and on the backend around 30mbps (out of
1000), due to recording 2 shows off our hdhomerun while I was watching this
other show.
-on the backend, top shows iowait hovering around 20-40%, which isn't bad
and was common while recording 3 HD shows and watching 1
-on the backend, iostat -xk 1 shows something interesting: my raid5 array
participants are all being used, but it seems that two of the drives hover
around 10% usage, while one is constantly pegged at 100% usage.  Is this
normal behavior in iostat -xk for a raid5 array?  it seems odd to me.

My backend is a C2D e6320 with 3GB of ram running Ubuntu 8.10 and the newest
myth-fixes.  Myth records to a raid5 array of 3x750gb drives with a 1.5tb
xfs file system on top.  It's connected to the network via 1000bT ethernet.

My frontends are AMD x2 4000+ with 1GB of ram running Ubuntu 8.10 and the
newest myth-fixes.  They are connected to the network via 100bTX ethernet.

Thoughts?  I'm intrigued by the what seems to be strange iostat results on
the backend...

-mike
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