| 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. 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.