Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I recently purchased a pair of 1TB Western Digital WD1002FBYS RE3 drives for use in an external RAID enclosure. I have found that they tend to drop out of the array after a while. Thinking it was the enclosure I tried them on another one but found the same issue.

So a bit of googling and I found this thread which suggests that:

WD's "RE" (RAID Edition) HDDs support Time-Limited Error Recovery ("TLER"): 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.

So now I wonder what SATA drives have firmware which is compatible with RAID arrays (esp. RAID 1, 5, but not 0)? I have not been able to come up with the magic set of keywords to ellicit the answer from Google. However, various sites suggest that Seagate & Hitachi are in general OK.

Does anyone have any generic (or even specific) guidance on how to work out if a drive's firmware may harbour code that is potentially an issue in a RAID>0 setting other than stating that it must be 'enterprise' ready?

share|improve this question

migrated from Jun 20 '11 at 16:34

This question came from our site for system and network administrators.

What enclosures are you using? – ErnieTheGeek Jun 20 '11 at 16:29
I think you misunderstood your links. The TLER problem you mention is only any issue for drives that are not RE drives. The drives you purchased are RE drives, and so shouldn't have that problem. – Joel Coehoorn Jun 20 '11 at 16:39
Yes, indeed - does look I misunderstood. Thanks to all for clearing this up. – nroam Jun 20 '11 at 17:16
up vote 2 down vote accepted

There is a good article at which describes this and also shows how you can override the settings so you can, for example, use a RAID drive in a desktop environment or use a desktop drive in a RAID environment (not recommended for various other reasons!)

We also bought a load of WD Green 2TB drives when they first came out and tried them on RAID with similar consequences.

Since running the WDTLER program to modify the settings, we have seen no issues with them dropping out of the array. That said, we generally use Seagate ES.2 SAS Drives for most of our critical storage and the WD Green drives just for backups

Hope this helps and good luck

share|improve this answer
Thank you. Looks like I may either have a couple of drives that are flaky or my enclosure is not up to the job. – nroam Jun 20 '11 at 17:16

The RE series you have do not have the issue you mention and the link actually notes this( as noted by @Joel Coehoorn). Green drives are a bad choice but the RE drives are used by many vendors such as Dell and HP. They are designed for enterprise use including RAID. Have a number of them in arrays on Dell and HP now and all work well

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.