[mythtv-users] Backend hardware advice - RAID suggestions

[Brad Templeton]

On Sun, Jul 16, 2006 at 11:42:02PM -0400, John Drescher wrote:
> I see a big problem with these calculations. You are assuming that the
> system is not running any type of power saving mode. For current
> athlon64/opteron processors with cool and quiet running the processor will
> consume around 25W.
> 
> Also at work I have an opteron 248 server with 4GB of PC3200 ECC DDR, dual
> processor board, 2 power supplies and 18 X 250 GB  WD SATA drives and the
> entire system draws ~300W under full load as reported by the apc ups that it
> is connected.

Yes, the processors are all getting good about power saving.  I have
not had much luck in getting good power saving out of disk drives,
there's always something popping up on a myth system that wants to
spin drives up.  RAID would make this even worse as you have to
spin up all volumes to do any activity.   In theory a non-RAID system
could isolate the files that get regular activity onto a single
drive and thus allow the others to spend more time spun down or in
lower power modes.    I haven't followed it of late but I know various
laptop linux projects have done work to try to get this to work better.
A really clever system would use a combination of flash and well designed
OS and daemon mods to never spin up the disks while the machine is
doing very little.

Of course with myth, you can, if you get fancy about it, program it to
wake up only for recordings, using wake-on-clock or wake-on-lan.  That's
no good of course if you are trying to make a big fileserver for use by
all sorts of workstations and frontends, there will always be somebody
wanting it.

An ideal Myth or DVR system might well use combinations of disks, flash
and ram to sleep most of the time and only wake up when recording or
if a user is active at a frontend.  That would be well worth it in
terms of power consumption and electricity cost in California.