[mythtv-users] TFW, Error: Write() -- IOBOUND ..... and mythbox crashed

[Ma Begaj]

DMA was always on ...

I tried something else ... I changed the IO scheduler in kernel from
Anticipatory to Deadline and changed the number of requests to 1024:

echo deadline > /sys/block/hda/queue/scheduler
echo 1024 > /sys/block/hda/queue/nr_requests

I started at the same time:
three recordings, mythcommflagging, transcoding and one watching recording.

I still get IOBOUND errors, but machine is not crashing ... hdparm -tT
is not giving better performance.  Changing scheduler helped maybe a
little bit, but it is not a solution.

Should my disks be faster? They are both on one IDE cable as master and slave.

Thanks.

M.



2007/10/18, William Munson <william_munson at bellsouth.net>:
> Ma Begaj wrote:
> > Hi,
> >
> > I had yesterday three recordings running at the same time (1x pvr150,
> > 1x pvr500). At the same time, I was watching a recording. And suddenly
> > my mythbox crashed and I had to reset it.
> >
> > I checked syslog and found nothing, but I found something in
> > mythbackend log file:
> >
> > 2007-10-17 23:32:05.673 TFW, Error: Write() -- IOBOUND begin cnt(2048) free(835)
> > 2007-10-17 23:32:10.724 TFW, Error: Write() -- IOBOUND end
> > 2007-10-17 23:32:10.731 TFW, Error: Write() -- IOBOUND begin cnt(2048)
> > free(1095)
> > 2007-10-17 23:32:10.735 TFW, Error: Write() -- IOBOUND end
> > 2007-10-17 23:47:10.183 TFW, Error: Write() -- IOBOUND begin cnt(2048)
> > free(1503)
> >
> > I checked the older mythbackend logs and I found more of these
> > messages in the last few days, usually when I had 2-3 recordings (SD)
> > running and watching at the same time.
> >
> > I have two IDE hard disks (2x 160GB WD) and 1GB single channel RAM.
> > One of these disks has a system and home partitions and a partition
> > for myth recordings. 2nd disk is only one partition for recordings.
> > Everything is ReiserFS. I was thinking to change it to XFS these days.
> >
> >
> > I run "hdparm -tT" and they are more or less the same for both disks:
> > root at mythbox:/tmp# hdparm -Tt /dev/hd[ab]
> >
> > /dev/hda:
> >  Timing cached reads:   1332 MB in  2.00 seconds = 666.17 MB/sec
> >  Timing buffered disk reads:  136 MB in  3.03 seconds =  44.81 MB/sec
> >
> > /dev/hdb:
> >  Timing cached reads:   1090 MB in  2.00 seconds = 545.26 MB/sec
> >  Timing buffered disk reads:  172 MB in  3.02 seconds =  56.97 MB/sec
> >
> > not pretty fast? this
> > http://readlist.com/lists/mythtv.org/mythtv-users/7/39724.html has the
> > same problem, and the disks have two or almost three times higher
> > "Timing cached reads".
> >
> > any ideas? I could buy new disk(s), but I think that these disks
> > should be handle 2-3 recordings and 1 reading at the same time.
> >
> > Thanks
> >
> http://www.mythtv.org/wiki/index.php/Optimizing_Performance
>
> check out the section on hard disk DMA.
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>


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