build out of a server advice

Lloyd Brown lloyd_brown at
Fri Jun 22 15:14:28 MDT 2012

At least with large, rackmount, enterprise arrays, the general consensus
with large drives is to use 2-drive parity, eg. RAID6.  Depending on the
load you put on the controller, there is a non-trivial chance that
you'll have a second drive failure in the RAID-group during the time
that you're rebuilding.  Frequently a rebuild on either RAID5 or RAID6
with that big of a drive, might take 24-48 hours or more, sometimes
longer.  Two failed drives in a RAID6 doesn't lose any data, but in a
RAID5 it would.

If you'll have a fairly light I/O load on the server, you might be able
to get away with RAID5, since the reduced load will let the RAID
controller (or kernel, for software-raid) spend more of its resources
rebuilding when a drive does fail.

Lloyd Brown
Systems Administrator
Fulton Supercomputing Lab
Brigham Young University

On 06/22/2012 03:09 PM, Merrill Oveson wrote:
> plug:
> Building a server:
> one 1 TB - for the OS and programs.
> four 3 TB raid 5 - which should give me 9 TB usable.  Correct?
> How reliable are the 3 TB drives these days?  Am I taking a big risk here?
> thoughts?
> Thanks
> Merrill
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