Hi Alex & *,
Zitat von Adam Goryachev <mailinglists@xxxxxxxxxxxxxxxxxxxxxx>:
On 16/09/15 04:44, Alex wrote:
Hi,
[...] but I'm
not sure I want to lose the extra space with creating a RAID6 array. I
believe RAID5 also has faster write speeds?
What disks are you using? Are they proper raid disks? A 12TB array can
have a soft read error every complete pass, and still be within the
disk-manufacturer's specs. If your disks are not raid-compliant, this
will stop your array from rebuilding, ever!
All four are WD30EFRX-68EUZN0. They're not the cheapest WD disks, but
they're also not the ones with the 5yr warranty. The last array I
built using disks with 5yr warranty exceeded their capacity before the
warranty expired.
[...]
(Chances are, your disks are above spec and won't give a problem. Do you
want to take the risk?)
There's always going to be some kind of risk, but I'm hoping someone
with the technical understanding about disk failure rates can tell me
if it's a prudent decision or not.
That depends on your requirements. What are the implications (for
you) if all the data is lost because two drives failed close to the
same time? Is that resulting cost more or less than getting a fourth
drive and using RAID6?
I just want to point out that double and triple disk faults are far
beyond theory - we've had a RAID6 crash last year, where three of 11
disks failed within 24h. Two were from one batch, the third from a
different batch.
Alex, you initially said this is to be a backup server - so if that
means the data is already redundant, then you may stick with RAID5.
But if this is your main data storage and you rely on that data being
available (i.e. quicker than restoring from backup will take), go for
RAID6 and keep in mind that even that won't prevent you from total
RAID loss.
Regards,
Jens
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