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

Jarod Wilson jarod at wilsonet.com
Thu Dec 29 01:51:46 EST 2005


On Wednesday 28 December 2005 22:37, Brad DerManouelian wrote:
> On Dec 28, 2005, at 10:30 PM, Yeechang Lee wrote:
> > 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.
>
> This actually sounds pretty typical of RAID 5 to me. Every write
> results in 2 simultaneous writes. Even slower when you're doing it in
> software. Great for redundancy, terrible for throughput. That's the
> trade-off.

Erm, software RAID 5 isn't *that* bad. I've got a sw RAID 5 array that only 
consists of four ATA drives, and can write at a sustained rate of 30MB/s 
without a problem. I've got a 5-drive U320 software RAID 5 array in another 
machine that does ~80MB/s without a problem.

-- 
Jarod Wilson
jarod at wilsonet.com
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