[GTALUG] Backups for files
D. Hugh Redelmeier
hugh at mimosa.com
Thu Nov 5 13:05:41 UTC 2015
| From: o1bigtenor <o1bigtenor at gmail.com>
| A tip - - - some of the drives marketed as applicable to NAS raid arrays really
| aren't applicable. You need to be purchasing drives that have ERC or error
| recovery control. I was slapped upside the head because I had drives that didn't
| have that but when I bought the drives (early 2012) NOBODY was talking about
| that.
I've heard that some RAID systems do know how to deal with such
drives. I haven't researched which ones.
Lots of us were talking about this (whining, actually). I usually
called it TLER, Western Digital's term for it. ERC is Seagate's name.
CCTL was used by Samsung and Hitachi.
Earlier it was possible to tell a drive to limit error recovery time.
Then the drive manufacturers locked this feature out on their cheap
drives. Grrr.
Disks with TLER / ERC / CCTL & LCC [Table of drives] (2011 March)
<http://hardforum.com/showthread.php?t=1590200>
I posted to this list:
From: D. Hugh Redelmeier <hugh at mimosa.com>
To: tlug at ss.org
Date: Thu, 28 Jun 2012 21:58:59 -0400 (EDT)
Subject: Re: [TLUG]: 3TB Harddisk sale
| From: Anthony de Boer <adb at adb.ca>
| I expect I'll be trying the WD RE4 Lennart mentions next.
My understanding is that RE and non-RE are the same EXCEPT for "TLER"
(a trivial firmware difference).
Without TLER, RAID won't work. A drive will spend so much time
recovering from a simple local error that the controller will declare
the whole drive offline. That is a big failure. It generally
requires the array to be rebuilt, possibly taking longer than the
actual MTBF!
That's how they do "market segmentation". Market segmentation is a
vendor's dream: sell essentially the same product at two different
price points.
If the drive manufacturing industry were not an oligopoly, this price
differentiation would disappear. In fact, I think Samsung's normal
drives were capable of TLER; that's been fixed by Seagate taking them
over.
More information about the talk
mailing list