I have a Windows Server 2003 R2 Ent server running with a C: drive and dynamic disk raid 1 Z: drive. The Z: drive mirrors two identical 1TB drives (same manufacturer, model number, and size - HDS721010KLA330). Amongst other things, the Z: drive holds the home directories. The 1TB drives have been installed a year ago.

Lately I've been starting to get very slow logins and when looking at the management console I noticed a few things:

  1. The dynamic Z: drive is resynching
  2. Only one of the disks of the dynamic drive is showing errors (a small yellow warning sign and "(Errors)" next to the drive status
  3. Even when the resynch is done, Disk 1 is still showing errors. And I don't know why but resynching is triggered again (haven't tested when)

You can see a screen capture of my disk management here: http://img109.imageshack.us/img109/4301/diskmanagement.jpg

So my questions are:

  1. Is there a way to get more details about the errors that Windows is reporting?
  2. Is this a faulty drive or possibly some other issue?
  3. What's the best way to solve this? I don't want to buy a new drive just to find out the troubles pop up again after a few months.

Thanks for the help!!

  • How are your backups? If they aren't good, get some other disk that the data will fit on ASAP and it copied! If those identical 1TB disks came from the same manufacturing run you may find the non-failing disk joining the other disk in failing soon. – Evan Anderson Nov 11 '09 at 23:35

You have a faulty drive and will need to replace it. Right now you have no redundancy anyway, as the two drives will not stay synced, so if there is going to be any delay in replacing the drive at least disable it, as that will restore the performance.


Thanks. Here's what I did: I broke the RAID1 and left the 'healthy' disk as the original drive letter. Formatted a new FS on the disk that showed as having errors, and now it seems healthy.

My question is: could this be a problem only with dynamic disk, and my hard drive is actually okay and functioning proper? Or should I still replace it?

  • 1
    Seeming healthy after a format doesn't necessarily mean it will remain healthy once you start writing data to it or reading it back. I would dump the drive and replace it rather than taking any further risk. – David Spillett Nov 11 '09 at 20:53

Load up HDTune, speedfan, or any number of other software tools that will show you smart data. If you see bad data there you have a hardware problem. Don't stop at looking at just the obviously failing drive it may be the other drive is about to fail.

Be prepared to replace 1 or both disks soon. Don't assume because it sort of works that nothing is physically wrong. More often than not physical errors in a drive can go undetected for long periods of time.


Reallocated sector count is a traditional age related failure but almost anything on the list could be the problem.


So I ran hdtune. On the drive that appeared to be okay hdtune isn't showing an errors. On the drive that had the warning sign when it was raided, I see a warning in hdtune. I really don't know if to interpret it as replace the drive or not. Currently it's used to backup the other drive it was mirrored with. I've attached a snapshot - please advise. Thanks!


  • 1
    SMART data doesn't always get triggered when a physical problem occurs. I'd trust the RAID 1 resyncing symptom over the SMART data. Use the disc for testing or manually backing up data if you want to be paranoid and backup the same data to 50 different hard drives but don't leave it in day to day use. It's no longer trustworthy as a production drive on a server or even in a desktop PC. – pplrppl Nov 12 '09 at 16:41

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