[mythtv-users] Fast Quiet Sata drive?
Terjesen Jens Peder
Jens.Peder.Terjesen at devoteam.com
Thu Mar 17 09:07:06 UTC 2011
Joe Hickey wrote:
On Wed, Mar 16, 2011 at 3:11 PM, Ken Mandelberg <km at mathcs.emory.edu> wrote:
> Again, I some times record 4HD Mpeg streams, while watching a 5th, and
> possibly even a commflag at the same time. I really don't think dropping
> down in performance is an option.
I'll reiterate something that has already been said here and seems to
have been overlooked:
In your initial post you said you are connecting this drive over USB.
That is going to be your performance limiting factor, not the drive.
I'm sure even the lowliest of modern 2TB drives (green or not) can
saturate the USB bus. If performance is a concern, USB is not the
proper storage interface!
FWIW, my WD 2TB green drive can easily handle 2 HD + 1 SD recording +
watching HD + commflag job and I haven't noticed any i/o issues, but i
also haven't pushed it to see how much more it can do either.
I can only agree that the USB interface will be the limiting factor.
I recently needed to clone a 120 GB 2.5" laptop disk using dd.
The first time I put the disk in a USB enclosure and cloned it to another USB disk on my backend with AMD Athlon II X2 250 CPU. This took nine hours.
Second time was after reallocating som bad sectors with SW from the disk manufacturer and reinstalling Vista.
This time the disk was mounted in the laptop with SATA and I booted it from USB with Linux.
Using dd piped through gzip on the laptop to a NFS mounted 3.5" disk on the backend via Gb Ethernet took three hours.
In this setup the compression with gzip was the limiting factor running at 96% CPU. The LED on the Ethernet socket on the laptop only blinked once in a while.
Admittedly there are several differnces in the two cases but I still think it indicates that USB is a limiting factor.
I have two backends in different locations, one with four 1.5 TB Samsung F3 and one with two 2 TB Samsung F4 using storage groups only, no RAID. I have never seen the disks as bottelnecks even with three DVB-S2 tuners in one and two DVB-S2 tuners in the other. Often recording several SD and HD channels while watching SD or HD. I don't do much comflagging as it has a bad hitrate on the material I record.
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