RAID without TLER

[Lennart Sorensen]

On Wed, Feb 20, 2013 at 01:41:10AM -0500, D. Hugh Redelmeier wrote:
> 1) they are quite a bit more expensive.

No, WD enterprise (yellow label) drives are expensive.

2TB Red: $120
2TB Green: $100 (but much slower)
2TB Black: $170

1TB Red: $85
1TB Green: $75
1TB Blue: $75
1TB Black: $95

So given the Red is rated 24/7 operation with time limited error recovery,
and has similar performance to the Blue, that seems pretty reasonable
to me.

> 2) according to the smallnetbuilder article, consumer NAS devices
>    don't use ERC.  Sounds odd to me.

Maybe not, but a drive that doesn't take very long to respond with
'bad read' is still good for any raid controller.

The time limited error recovery is what RAIDs have needed.  ERC isn't
needed, but can be useful for high end RAID controllers perhaps.

A drive that disappears for 2 minutes trying to read a failing sector
will cause the drive to drop out of most RAIDs, which is what the WD
Red is meant to avoid.

-- 
Len Sorensen
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists