Probabilty of Hard Drive Failure?

stubie_doo · 27 Jan 2007 at 19:30

Thinking of buying new drives for raid array.

I understand that storing your data on multiple drives will increase the probablity of data loss. My question is therefore how rare is it for a hard drive to die?

rpstewart · 27 Jan 2007 at 19:49

The Mean Time Between Failure rating of a drive gives the average length of the life of a drive, current drives are approaching 100 years although I'm not sure if the figure takes into account how often the drive is power cycled.

That said we should therefore expect HDDs to operate without failure which is clearly not the case.

The problem with striped RAID (RAID0) is that it relies on the two (or more) disks operating as one so can be very susceptible to minor drive hiccups which would not cause any major issues on a single disk system. I've had a number of RAID0 arrays fail on me for no apparent reason, the array simply fails to work and cannot be recovered yet there's nothing wrong with the disks and I've quite happily gone ahead and reacreated the array on the same disks and it's gone on working fine.

There is nothing inherently wrong with RAID0, it's a great way of getting better speed out of cheap disks but you have understand that things can go wrong and either be willing to lose everything or keep good backups.

stubie_doo · 27 Jan 2007 at 20:27

Thanks, I hadnt actually thought about the array itself failing! I also didnt realise you could recover the array. Does this mean if the mothboard dies I will be able to re-create the array on a new one?

Dist · 27 Jan 2007 at 20:40

i think if a motherboard/raid controller fails then to recreate the array yourll have to use the same make (possibly even model/version) of the raid controller to recover the data from the hdds, so even though it is recoverable, it can still be difficult to get the data back if youre using a rare/hard to get raid controller.

rpstewart · 27 Jan 2007 at 20:50

stubie_doo said:
Thanks, I hadnt actually thought about the array itself failing! I also didnt realise you could recover the array.

Sorry, I wasn't quite clear in my original post. None of the RAID0 failures which I've had were recovered, I was able to reuse the disks but the data from the original array was lost.

Methanoid · 29 Jan 2007 at 13:23

Worth mentioning that HD failure is often as aresult on inadequate cooling. Whack a fan in front of them and they last longer !!

stoofer · 29 Jan 2007 at 14:39

just had my 2nd seagate in 2 years die on me. and as it was an RMA it only had 12 months warranty, now expired, one useless drive and one brand Im going to avoid for a while...

RAID 0 is fine and dandy, but I wouldnt put critical data on it unless I backed it up somewhere else. RAID 0 with 2 drives basically doubles your chance of drive failure, 4 drives quadruples it.

accod · 29 Jan 2007 at 15:15

stoofer said:
just had my 2nd seagate in 2 years die on me. and as it was an RMA it only had 12 months warranty

Is that true that a 2 month old Seagate which is replaced will then only have a 12 month warranty?!?