>>Hi All
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>>I have a server with 2 x 500Gb drives in a RAID configuration. I am not sure what RAID config it is as these are rented servers. The 2 drives mirror each other and I would assume that the server is supplied as much "stock standard" as possible. The server has been operational for 6+ years and has worked fine.
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>>A few months ago, maybe 6 or more, I noticed under Computer Management -> Disk Management that one of the partitions (there are 3) had a warning along the lines of "failed redundancy check" with a small yellow triangle alert icon. I choose the option to resync the drives and this seemed to solve the problem. Now last week this happened again and so I resync'd again. Now today this happened again. I resync and it seems to work fine but obviously this is something that needs further investigation.
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>>Is this a sign the drives are failing? Or would it be the RAID controller? I have contacted their support department but thought I would ask here fwiw as well.
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>>I have a backup server as well and can switch over all functions to it but don't want to go through the hassle if its not warranted to do so i.e. if people in the know of these things don't think its a necessary move - I am not a hardware guy.
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>Those are classic symptoms of failing hardware - increasing frequency of problems. RAID1 is mirroring, you should be protected against a single drive failure. That said, depending on the type of failure, a single drive failure could take down RAID controller and server as a whole (I've seen this happen). Six years is late middle age for typical magnetic hard drives.
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>Replace the failing drive ASAP. Replacement with the same make/model would be ideal but will likely be impossible to find if the original drives are 6 years old. You can replace it with any drive of the same capacity or larger - if you use a larger drive, the extra space will just be unused.
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>The important thing is to get a RAID-specific hard drive that supports TLER (Time Limited Error Recovery). Western Digital RE enterprise drives support this, I believe their Red NAS line does as well. If a drive does not support TLER, it may on occasion take up to 20 seconds or so for internal maintenance/error correction operations, which the RAID controller will treat as a drive failure. TLER ensures the drive never takes longer than the RAID controller's timeout setting, typically 7 seconds.
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>IOW if you use a non-TLER drive you'll get "false positive" drive failures.

Al, additional question - how do you find out which drive has the problem?