build out of a server advice

Lloyd Brown lloyd_brown at
Fri Jun 22 22:07:02 MDT 2012

On 6/22/12 4:17 PM, Merrill Oveson wrote:
> What's considered a large drive?  2 TB, 1.5 TB?
Shorter answer:

1TB or lager, SATA 7200 RPM is going to be a "big drive" where you
should do RAID6.  Smaller (up to 450 GB, I think) SAS or FC disks,
usually 10,000 or 15,000 RPM, are the "smaller" drives where you can
probably do RAID5 okay.  This may change in the future.

Longer answer:

The answer is "it depends".  Really it's more of a continuum, and the
real issue is how likely it is that a second failure will occur (based
on drive MTBF) during the rebuild.  Essentially, how much risk are you
willing to tolerate?

However, as a general rule, the "large drives" are usually the 1TB and
above, usually SATA 7200 RPM drives, that take a long time to rebuild. 
If you get the 10k or 15k RPM SAS or FC drives (I think they're up to
about 450 GB these days), they'll be much faster, due to their higher
rotation speed, the dual-path interfaces on the disk (SATA is
single-path), etc.


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