[mythtv-users] Odd i/o issues

Kevin Kuphal kkuphal at gmail.com
Tue Jan 13 21:23:18 UTC 2009


On Tue, Jan 13, 2009 at 3:13 PM, Michael D. O'Brien <obrienmd at gmail.com>wrote:

> 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...


smartd?

Kevin
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