On Tue, Sep 27, 2011 at 8:53 AM, Lisa Kachold <
lisakachold@obnosis.com> wrote:
> These are the current limitations with non-enterprise drives in hardware
> RAID (especially with WD drives):
>
> a) Time Limited Error Recovery:
>
> TLER is not enabled in all WD drives manufactured after 2010 (unless you pay
> for "RAID Enabled" Enterprise level), so RAID out of the box is
> problematic. As a non-TLER HDD fills up with data, the error detection
> firmware might take too long, and the RAID controller may drop that HDD from
> a RAID array. This timeout is typically around 10 seconds with Dell
> integrated driver/host RAID solution.
>
> Of course with WD drives we used to be able to get a utility (downloadable
> from Western Digital site) to enable TLER so it works for hardware RAID.
>
> WDTLER.EXE utility (originally developed by Western Digital, but
> discontinued, yet still downloadable from some 3rd party sites) used to
> allow for the enabling or disabling of the TLER parameter in the hard disk's
> firmware settings allowing the user to determine the best setting for his
> particular usage as either a stand-alone or RAID drive. This utility is
> written for DOS and a DOS bootable disk is required with this utility to use
> it.
>
> Western Digital now claims that using the WDTLER.EXE tool on newer drives
> can damage the firmware and make the disk unusable. The WDTLER.EXE tool is
> no longer available from Western Digital, and new disks will not be able to
> have the TLER setting changed.
>
> Most WD "Desktop class" disks cannot have the LTER setting changed as newer
> drives; therefore will not provide stable RAID in Perc LSI drives.
>
> b) SATA Desktop Drives are not Enterprise Drives:
>
> For example, Western Digital enterprise drives such as Raptor, Caviar RE2
> and RE2-GP (RAID Edition) come with TLER Read "Enabled" (7 seconds) and TLER
> Write "Disabled" (0 seconds) while desktop drives such as Caviar SE, SE16,
> and GP come with TLER Read and Write Disabled (0 seconds). Dell refers to
> their Enterprise Drives as Tier1 and Tier2.
>
> So, we know the risks, RAID failure, short lifetime, inability to rebuild
> the RAID due to TLER off.
>
> Is anyone successfully using basic (Desktop class, aka cheap) SATA drives
> with hardware controller cards?
>
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