[mythtv-users] Samba 3 better than NFS 3 for recording over Ethernet

Yeechang Lee ylee at pobox.com
Thu Dec 29 01:30:05 EST 2005

Jarod Wilson <jarod at wilsonet.com> says:
> Something odd going on there, I have an almost identical setup for
> my master backend, and NFS works great at handling multiple HDTV
> streams (both my HD capture devices are in slave backends that write
> to the master via NFS), along with the occasional SD stream thrown
> in as well.

To make a long story short, my 2.8TB JFS-on-LVM2-on-software RAID 5
array has certain mysterious performance bottlenecks that result in
7.5-10MB/s local write speeds, despite eight spindles and two 3Ware
7506 controller cards in JBOD mode and on separate buses and with
iowait never going above a few percentage points at the very
most. Over the network that's even slower, of course.

I've going to be rebuilding the array after backing it up to an
Infrant 600 (the clear winner, in my mind, among the recent spate of
"NAS in a shoebox" offerings popping up all over the place) with four
500GB drives I'll be temporarily using in RAID 0 for the time being,
and am looking forward to finding out whether the bottleneck is in
mdadm, lvm2 (the likeliest suspect in my mind; none of the several
academic self-assembled terabyte-RAID 5 array setups I've read
benchmarks for online seems to use it, although otherwise essentially
identical), JFS, or elsewhere. I would be surprised if, once I reach
write performance on the array closer to theoretical potential, I can
use NFS to stream recordings to it without any trouble. But in the
meanwhile I'm glad Samba lets me stream a HDTV recording while also
playing back a HDTV stream with no IOBOUND error messages (except the
very occasional one or two if I'm doing something disk- but non-MythTV
related on the frontend/backend MythTV box); after a month of butting
my head against seemingly-endless IOBOUND messages with NFS v3 that's
a good thing, believe me.

Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US

More information about the mythtv-users mailing list