[mythtv-users] An LVM'd drive died! What do I do...

[Steve Adeff]

On Thursday 27 October 2005 13:02, Brandon Beattie wrote:
> On Thu, Oct 27, 2005 at 05:07:50PM +0100, Alexander Fisher wrote:
> > Other hints ...
> > Don't put more than one ide drive on a single ide channel.   A failing
> > drive often takes out the bus.  SATA drives make sense, but SMART
> > support for SATA is still under development.  You should also make
> > sure that your SATA chipset has got linux support!
>
> Do you have any references about this?  I've never seen this happen in
> about 50 drives I've seen fail.  .. The only time I've seen more than 1
> drive go out at once is due to an electrical problem in the system.
> I've seen ruined drives on the same power cable, power supply, but not
> the same IDE channel.
>
> SATA doesn't offer any performance that I see worthwile in a media box.
> Having a single disk on an IDE port only helps if you're accessing two
> drives at once.  Although this can happen in a media box, Myth doesn't
> need it.  If you want to do it for fun that's one thing, but it's really
> not needed.  As I've said before, I've saved 5 35Mb/s streams and watched
> 1 20Mb/s stream on a single 7200 RPM drive.  Myth buffers data when
> storing to maximize storing to the FS.  I've pushed 99MB/s read and
> 65MB/s write to 4 drives (Using only motherboard ide channels).  That's
> the equiv of 40 1080i streams read or writing 26HD streams at once
> (Theoretical).  If you're going to be recording more than 8-10 HD
> streams at once, or pushing 10+ HD streams to frontends then you may
> want to start _thinking_ about SATA.  If you're doing SD then the
> numbers I'd say would be 20 saving and 30 playback... (You'll max
> network before having problems reading from a single drive).  Also, in
> my testing, It was something like 10% slowdown when doing raid 0
> striping and using two drives on the same ide channel.  However, if we
> figure one drive gives us 100%, two drives give us 200%, then 10% loss
> gives us 180% throughput, so you'll get more throughput if you put two
> drives on the same channel rather than not using it at all.
>
> SATA is good, but it's overkill.  SATA really shines if you're striping
> drives, then it's very helpful to have it on it's own channel.  There's
> no reason though that 99% of people should ever stripe drives for a Myth
> box.  I did it for 6 months, it was fun to benchmark and show off.
> However, your system is only as fast as the slowest point.  I've found
> in HTPC's that your root partition and its FS, or the FS with the myth
> database on it make a more noticeable effect on usability.  XFS(best),
> then JFS, then Reiser4, then ReiserFS, then ext2, then ext3(worst) make
> a large difference.  Brand of drives also makes a large difference (All
> my Seagate drives run 15%-40% faster depending on the tests I run, over
> the Maxtor ones I have).  I ran most all my tests on Maxtor's using XFS
> as for how many streams I could push.
>
> I currently have 4 HD tuners and 2 frontends in my MythBox.  I often
> record 4 shows at once and while watching another.  I've chosen to go
> with LVM for my 6 drives and 1.3TB of data.  I also picked ReiserFS (Not
> reiser4, XFS, or JFS) because I've found shrinking a FS to be very
> useful when dealing with a mythBox.  Since ReiserFS is really the only
> FS that supports shrinking with LVM, I use it, even though it's the
> worst performing for throughput.  I've never had a single problem with
> disk throughput.  It's an AMD 2500, 512MB ram (It never uses over 120MB
> unless it's commercial detecting, then it will use 300MB's).
>
> Point is, if you're on a budget, there's no need to pay extra for
> "fastest" or "best" unless you're in a pissing contest.  I only
> recommend paying more for reliability and suggest people get seagate
> drives with a 5 yr warranty, and accept they will be faster and quieter
> than maxtor, Western Digital, or other brands of HD's.
>
> --Brandon

well, right now, newegg sells the WD3200JD/JB 320GB SATA and ATA100 drves, 
with roughly a $5 difference at $130. its slightly slower, and <1db louder 
than the seagate drives, but also much much cheaper. It also only has a 3yr 
warranty, but I personally have never kept a large storage drive in ciritical 
use areas for even this length of time, they've either failed a SMART test or 
were replaced by larger drives. 2 years ago I was using a bunch of 120gig 
drives, replace 3 of those with 1 new drive now, I assume a similar if not 
accelerated situation will continue to occur.

though a RAID 5 SATA controller is about $50 more than an ATA100 one. But if 
this is not a concern for you then SATA is not that bad of an option and I've 
found it runs wonderfuly on my nForce board.

Steve