WD20EARS + RAID 5 considerations

WD Internal Drives Desktop & Mobile Drives
1

Hi all. I would like to know if  these WD20EARS can be used in Raid-5 configuration (Windows 2008 Server). I’m considering buying 4 of them because they are cheaper than other models, but I would like if someone can confirm they will work or not. I will be using them with Intel server motherboard (with LSI INTEL EMBEDDED SERVER RAID TECHNOLOGY II).

If they are not adecuate, i would like to know the reasons (performance? compatibility? etc.?).

Thank you for taking your time replying.

2

no, they are not adequate for RAID drives. You will end up with broken RAID just about every boot. The drives do their own error checking, and it takes too long for them to respond and the RAID controller thinks the drive has gone down, and breaks the RAID.

It is something they refer to as TLER (Time Limited Error Recovery) that some of the other drives have, but the green drives do not. What it does is to limit the error recovery time so that the drive isn’t dropped from the RAID. The green drives will try to recover from an error and take long enough for the RAID to drop it. (It can take some drives as long as several minutes for error recovery, and TLER drives stop it after about 7 seconds, and RAID controllers will drop the drive after 7-15 seconds)

Also, the green drives take longer to wake up, and the RAID will drop the drives because of that, too.

3

Drives do not know or care what data you store on them, so you can use them in any raid configuration you want.  Some BROKEN hardware raid controllers will freak out if a drive takes a little too long to respond.  Proper hardware raid controllers or software raid ( or fakeraid ) works just fine.

4

True that most hard drives will not know how they are set up but all Caviar Greens will only be “supported” from WD in software RAID 0 / 1.  Also with the “green” features, the RAID might be “choking” on the access.

5

My RAID5 with 4 WD20EARS drives is working well… no drop outs, no failures, everything working fine for several months. But I am using an Adaptec 3805 controller. I have heard of less than desirable results with lessor RAID controllers.

6

Yeah, same here.  I have a 4TB RAID5 with three WD20EARS drives.  One drive was DOA more or less but got that replaced quickly.  Since then it has been rock solid.  No errors/rebuilts/hiccups or anything for me.