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A couple of our servers have ST32000641AS (2TB Seagate desktop drives) in RAID 10 using an Adaptec 2405 controller. I've been told by Adaptec that this is a bad idea and we have, in fact, already seen one raid system go down using these drives. Since this is a 24/7 system, my question is whether it would be possible to switch over to WD RE4 2TB raid edition drives (model WD2003FYYS) by hot swapping them, one by one until we've migrated over. We would wait between each drive to make sure the raid has rebuilt itself.

In theory, this should work... however, one thing I can't figure out is whether these drives are the exact same size or not. Unfortunately, the raid build on the ST32000641AS drives are partitioned to capacity. If the WD2003FYYS drives are even the slightest bit smaller, it's not going to work. Any ideas on where I can go to learn whether the WD2003FYYS drive is exactly as big (or bigger) than then ST32000641AS?

Yes, I realize that both drives advertise themselves as 2TB drives...

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What you want to do will work but why on Earth would anyone use desktop drives on a critical system? Get real and get proper server grade drives. – John Gardeniers Aug 21 '12 at 0:53
@JohnGardeniers That's what he is doing! – Michael Hampton Aug 21 '12 at 1:37
@JohnGardeniers Eh? They aren't sold as desktop drives. What is it that makes them desktop models, in your opinion? – Michael Hampton Aug 21 '12 at 6:28
One of the problems using desktop drives is with TLER. By swapping out the drives one at a time, you may end up exacerbating the problem on the remaining three drives. Do make sure you have multiple, current, tested backups. We have had a similar situation and ended up creating a parallel RAID 10 system with the RE4 level drives instead. – tegbains Aug 21 '12 at 6:51
Thanks for all the comments. For the record, it was our server vendor who sold us the server with desktop drives in it. They claim to have sold "hundreds" of raid systems using desktop drives, with "no problems". However, we've learned the hard way that it is definitely a bad idea because, as @tegbains has noted, desktop drives lack TLER and the controller dropped two drives at the same time and the server crashed. Neither drive tested as "bad"... just a lot of "aborted commands". – Curtis Aug 21 '12 at 15:06
up vote 1 down vote accepted

The manual for ST32000641AS (alternative link) says that the drive has 3,907,029,168 guaranteed sectors, while the specifications for WD2003FYYS (alternative link) say it has 3,907,029,168 sectors. Therefore the drives have the same capacity.

share|improve this answer
Thanks, @CristianCiupitu! This is exactly what I was looking for. I guess I should have thought to check the manual. I guess I didn't expect the manual to provide the specs in such great detail. – Curtis Aug 21 '12 at 15:10

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