On Thu, Nov 5, 2015 at 12:05 PM, D. Hugh Redelmeier <hugh@mimosa.com> wrote:
| From: o1bigtenor <o1bigtenor@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.
This sounds like a problem looking for a solution -- - - a software hack to fix a hardware problem - - - I know 0 about programming or I would be looking into it already!
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@mimosa.com> To: tlug@ss.org Date: Thu, 28 Jun 2012 21:58:59 -0400 (EDT) Subject: Re: [TLUG]: 3TB Harddisk sale
| From: Anthony de Boer <adb@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. ---
Very interesting - - - time for some hacker ingenuity!!! Anyone that knows this stuff care to hand out some pointers? Dee