[mythtv-users] Dec 2008 - State of the Art - Hard Drive Recommendations?

[Martin Bene]

Hi Sandy,

> What would you say are the most important criteria for selecting a PVR
> hard drive?

You may get more meaningful results with a better description of what you're actually looking for:
 - frontend?
 - backend?
 - garage or living room?
 - how big is "big enough" ?

That being said, I'll just asume that
 - you're looking for a harddisk for a Backend
 - heat/sound are moderately important but noiseless is not a requirement
 - "big enough" is impossible anyway :-)

> 1. Is it Interface? PATA? SATA? ATA-100, 133, 150, 300?
That should be easy: SATA. Parallel ATA isn't any cheaper, new drives are mostly SATA-only anyway, current motherboards offer more sata ports and the cables are much easier to handle as well.

> 2. Capacity? Is it simply Gigabytes per Dollar (G/$) or do drives just
> get flaky over a certain size?
I'd mostly go by G/$; 1TB Disks are fine in my experience. The Seagate 1.5TB was problematic with flakey firmware (SD15 - SD19); current drives seem to be OK, old drives can (and must) be updated by the user before they can be used for myth.

> 3. Is it Mean Time Between Failure (MTBF)? Is this a meaningful metric
> anymore?
The big/cheap sata drives are regarded as "desktop" products by the manufacturers; I'D say MTBF is pretty useless as a metric for these drives. Manufacturer Warrany of 3 or 5 years with simple handling of reiar/replacement is much more important for me.

> 4. What about RAID? Good or Bad? Good for peace of mind, Bad for
> performance? Recommendations for/against using RAID? What
> about software raid (useless?)
For most myth systems HD Performance is not really a problem: throughput for recording is limited by the data rate of the video source and actually fairly low even for high quality HD recordings. Same thing for playback. So, for a myth box capacity is much more important than performance.
As for raid, I use a 5-disk (1.5TB) software raid5 on my mythbox, so I obviously consider softraid to be a valid option:

* hardware raid controllers for > 4 disks are quite expensive
* in case of a controller failure, you'll be quite limited in choice for a replacement that can read your old data.
* softraid will work regardless of controller used to connect the drives to your mythbox
* overhead/performance on a modern system isn't a big issue.
* configuration/maintenance can be an issue.

> 5. Rotational Speed? Is it a factor?
> 6. Average Seek Time? Do technologies like Western Digital Intelliseek
> make any difference or just get in the way?
For big affordable disks you're pretty much limited to 7200k drives with reasonably similar performance and seek times - high speed disks like the WD raptors are of course nice but I don't find I actually need the performance benefits they give. Also I'm not sure about cooling/ventilation requirements for the faster disks, might be mire difficult to keep them from overheating. If you run your system in ca closet this can easily become a problem.

> 7. Vendors? Seagate? Western Digital? Hitachi? Samsung? Any warrenty
> horror stories? Others to consider?
Mostly seagate here, had to do a couple of RMAs over the years: process is fairly painless and worked reliably, so no complaints there. The biggest problem with them so far was the 1.5TB Firmware fiasco - both the problem itself and the handlying of this problem by seagate support were quite aggravating.

> 8. Cache size? Since this is mostly a Write operation activity does
> cache really affect performance? How important is a large cache?

16 or 32 MB should be OK;

> Ultimately ... what do you recommend and why?

For me capacity was the most important property, which maske the choice very easy: no competition for the seagate 1.5T drive available :-)

With requirements a bit less extreme, I'd say the current bunch of 1TB SATA drives should give you a few acceptable choices.

Bye, Martin