Some background info: Western Digital released these new Green hard drives using the 4kb drive sector, dubbed "Advanced Format". All drives up until this point were using a legacy 512 byte hard drive sector. See: http://it.anandtech.com/show/2888
This is relatively unimportant, as my question is pertaining to RAID. Older WD desktop drives (Velociraptor excluded) could not be safely used in RAID because TLER was turned off. A tool called WDTLER, that runs in a DOS PE, enables you to switch on TLER on their desktop drives, enabling you to use them in RAID safely. Their Enterprise RE drives had TLER turned on by default. However, starting about October 2009 to December 2009, WD updated their firmware on all of their desktop drives so that TLER could no longer be enabled.
So, the question is, has anyone had experience with enabling TLER on the new WD20EARS? This drive debuted in January 2010, so presumably, TLER is disabled based on previous trends. However, several reviews on Newegg mentioned that they were using these in RAID arrays, but were they just overlooking the TLER issue or did they actually find a fix?
I tried to run WDTLER on my new pair of WD2001FASS with no luck. It just said TLER cannot be enabled. It also "ruined up" my drive that the reported capacity was down from 2TB to 450GB. I have to run a MFT format to bring it back to normal.
On the contrary, I have successfully turned on TLER on around 20 WD green drives i owned during 2008-2009. They are all 1.0TB and 1.5TB drives (EACS & EADS).
I guess the quick answer is that DROBOs don't use RAID. The long answer is that ears drives should work fine in raid as long as they don't get mixed with 512kb drives. Even then you just need to set your jumpers correctly.
Enterprise drives are for RAID. Desktop drives are for the rest of us. We just try to do the best we can with what we've got. You won't find 10TB of storage using less power than those five wd20ears. Cool, quiet, easy on power, and HUGE (by most DROBO user standards). That's what this machine is about.
Linux/BSD does not need TLER; Windows onboard RAID and all Hardware RAID does need TLER, or you will experience disk dropouts/broken arrays as soon as one of your disks develops a bad sector requiring more recovery time than 10 seconds, at which point the disk is detached from the array and marked as failed or 'free' or 'non-member', etc.
Since Linux and other free operating systems handle disk timeouts differently, they do not require the TLER feature and will not experience drive dropouts due to longer recovery times.
TLER also can be dangerous when you lost your redundancy, such as a RAID5 and rebuilding, TLER can be dangerous; the disks give up early in their attempt to recover data in the assumption that the RAID redundancy can do a better job; but if you lost your redundancy then TLER can increase the risk of a weak/bad sector; disrupting your ability to recover data.
If you truly want a reliable storage system, have a look at ZFS. It is not supported by many OS yet, but several derivatives of the main operating systems that support ZFS (Solaris, OpenSolaris, FreeBSD) have been developed with an easy web-interface to ease the learning curve needed to operate this system effectively. ZFS is very maintenance free and has reliability features unmatched in other filesystems or RAID architectures. The closest rival to ZFS is Btrfs (b-tree fs or butter fs) which works primarily on Linux, but is in much earlier stage of development.
If you cannot opt for ZFS, then i would highly advise investing on a good backup strategy, instead of relying on traditional RAID and legacy filesystems too much. Once you get to know ZFS you begin to understand how primitive the commonly known filesystems actually are.