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Anyone here use NAS (Network Accessible Storage) devices?
drventure:
kahlid74 makes some good points, but for a home environment, I'm not sure it's worth the extra cost for full on raid certified drives. But YMMV.
One thing that IS important to point out is with raid, you have basically 2 choices (3 if you're willing to spend a good bit more $$$)
1) Take two drives and mirror them. You get faster read access, the same write access, and if one drive fails, you still have the other drive till you replace the failure.
or
2) take two drives and stripe them, you get faster read and write access, BUT if either drive fails, you're toast. So +absolutely+ make sure you have good backups. The reason this option is considerably more dangerous is that you now have 2 drives, but a single "system", so if either drive fails, the system fails. Since both drives have the same MTBF, this effectively means you're +decreasing+ the MTBF to half what it would be with only a single drive. In other words, the system is far more likely to fail earlier than using just a single drive.
The other option is striped with parity, but that usually requires 5 drives and is a bit more difficult to setup.
I've used a mirrored setup for years, with reasonably regular backups. The mirrors have saved my bacon more than once.
kahlid74:
--- Quote from: drventure on April 23, 2013, 10:51:51 am ---kahlid74 makes some good points, but for a home environment, I'm not sure it's worth the extra cost for full on raid certified drives. But YMMV.
One thing that IS important to point out is with raid, you have basically 2 choices (3 if you're willing to spend a good bit more $$$)
1) Take two drives and mirror them. You get faster read access, the same write access, and if one drive fails, you still have the other drive till you replace the failure.
or
2) take two drives and stripe them, you get faster read and write access, BUT if either drive fails, you're toast. So +absolutely+ make sure you have good backups. The reason this option is considerably more dangerous is that you now have 2 drives, but a single "system", so if either drive fails, the system fails. Since both drives have the same MTBF, this effectively means you're +decreasing+ the MTBF to half what it would be with only a single drive. In other words, the system is far more likely to fail earlier than using just a single drive.
The other option is striped with parity, but that usually requires 5 drives and is a bit more difficult to setup.
I've used a mirrored setup for years, with reasonably regular backups. The mirrors have saved my bacon more than once.
--- End quote ---
My apologies, my intention was never to say you have to buy raid certified drive, only to warn you that in most cases, those regular drives you buy will die faster in your NAS then in your PC. So make sure your data is backed up for the worst case scenario.
drventure:
--- Quote from: kahlid74 on April 23, 2013, 11:25:15 am ---My apologies, my intention was never to say you have to buy raid certified drive, only to warn you that in most cases, those regular drives you buy will die faster in your NAS then in your PC. So make sure your data is backed up for the worst case scenario.
--- End quote ---
No worries. That's generally true. You +can+ setup nas drives to sleep as well (in my case, I'm running win7 on my "server" and just sharing the drives, so I can sleep them as you would a desktop PC). I've got some backup processes and other things that run on that machine, though, so I'm not sure how much they actually sleep.
NowI'm curious, I'll have to check that out...
shponglefan:
I'm curious to know how much NAS drives really do run active vs desktop PC. In my case, I mainly use my NAS for storage, so I'm not accessing it all that much (certainly not as much as my regular PC), so I can't imagine they would see more 'mileage' on the drives. And I've got hibernation active again on the NAS, so...
I agree though that drives like WD Green which are designed to spin down to save power would be wholly non-ideal in a NAS, since they would be constantly spinning up/down. I use a WD Green drive as a backup on my main PC, and notice that behavior a lot. But now that I've offloaded my files to the NAS, I don't really need the WD as much...
MonMotha:
I've not noticed particularly higher instances of failure, but my storage environments are more like normal PCs that just happen to run 24/7, so if you have one of those little SAN enclosures or something, things may get a bit hot or whatever.
What IS somewhat problematic is the handling of error reporting by the disk. Mostly for market segmentation, but I'm sure it makes them a hair cheaper, too, the "consumer" drives don't report errors very well. In many cases, they'll just return invalid data as though it were correct. This can be a real bummer when operating RAID arrays. If you have an optimistic read strategy on a RAID 1 (where you only read from one device rather than always read from them all and check the integrity), you could serve up bogus data. During rebuilds, you'll silently rebuild the array with bogus data. The "NAS grade" drives actually check for and return a read error when one occurs. It still won't save your data, but at least you'll know that you need to reach for the backups rather than having to endure silent data corruption that many go unnoticed for weeks, months, etc.
Moral of the story: RAID is not a backup in any case, and especially not when using cheap drives.
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