3 ms·

Good analysis and I've wondered this myself, though this assumes failure rate is linear rather than accelerating over time, that failures are independent (vs a

by npunt 10y ago

Good analysis and I've wondered this myself, though this assumes failure rate is linear rather than accelerating over time, that failures are independent (vs a design flaw that causes them to fail around the same time, which happens enough that people recommend buying drives from separate batches / date of mfg), and you have to factor in the cost of a larger RAID array + power to support the same level of reliability. It may make sense in data centers but the smaller you go, the bigger the jump in cost from drive arrays (e.g. a synology 2-bay, 4-bay, 5-bay, and 8-bay are each pretty significant jumps). I too am on team HGST because of that.

Veratyr 10y ago
Yeah it's by no means perfect. Another problem that comes up is that when one drive fails the load on the others increases, which can lead to more failures. It'd be really interesting if someone's looked into the stats here but I haven't seen it. As for paying for the power+drive bays, that's true of the consumer NAS devices but if you buy used servers instead it isn't such a problem. For the price of a 12 bay Synology disk station you can buy a 24 bay, 4U, used Supermciro 846E16-R1200B with a couple of CPUs and 144GB of RAM. Not a great choice if you're short on space but can be decent otherwise.
kgermino 10y ago
>though this assumes failure rate is linear rather than accelerating over time, that failures are independent (vs a design flaw that causes them to fail around the same time, which happens enough that people recommend buying drives from separate batches / date of mfg) I saw this happen once. A drive died, it was replaced and while the array was rebuilding several more failed. They ended up losing the entire SAN. It wasn't a good day.
- throwaway7767 10y ago
  This is why I try not to buy many disks at once, just buy one at a time, and if I need more than one I'll go to different stores. Too much chance of getting a bad batch of disks and having the whole array go down (I've had that happen too). Of course, that doesn't work at a large scale, but then you have other methods of increasing redundancy.

by npunt 10y ago

Veratyr 10y ago

Yeah it's by no means perfect. Another problem that comes up is that when one drive fails the load on the others increases, which can lead to more failures. It'd be really interesting if someone's looked into the stats here but I haven't seen it. As for paying for the power+drive bays, that's true of the consumer NAS devices but if you buy used servers instead it isn't such a problem. For the price of a 12 bay Synology disk station you can buy a 24 bay, 4U, used Supermciro 846E16-R1200B with a couple of CPUs and 144GB of RAM. Not a great choice if you're short on space but can be decent otherwise.

kgermino 10y ago

>though this assumes failure rate is linear rather than accelerating over time, that failures are independent (vs a design flaw that causes them to fail around the same time, which happens enough that people recommend buying drives from separate batches / date of mfg) I saw this happen once. A drive died, it was replaced and while the array was rebuilding several more failed. They ended up losing the entire SAN. It wasn't a good day.

throwaway7767 10y ago
This is why I try not to buy many disks at once, just buy one at a time, and if I need more than one I'll go to different stores. Too much chance of getting a bad batch of disks and having the whole array go down (I've had that happen too). Of course, that doesn't work at a large scale, but then you have other methods of increasing redundancy.