My PowerEdge 840 is configured as such:
Windows Server 2003 SBS
SAS 5/iR controller
1st Virtual Disk - Raid 1 (Mirrored) config
SLOT 0 -- Seagate ES3 750GB, 7.2K, 3.5 SATA HDD
SLOT 1 -- Seagate ES3 750GB, 7.2K, 3.5 SATA HDD
2nd Virtual Disk - Raid 1 (Mirrored) config
SLOT 2 -- WD RE4 1 TB Enterprise Hard Drives: 3.5, 7.2K, SATA II, 64MB Cache - WD1003FBYX.
SLOT 3 -- WD RE4 1 TB Enterprise Hard Drives: 3.5, 7.2K, SATA II, 64MB Cache - WD1003FBYX.
One of the original Seagate recently failed (At least that what I believed happened). Said Resyncing then failed the resyncing. Now the drive is no longer visible in BIOS. SLOT 1 is now blank and the status of the array is Degraded. (I haven't physically removed the drive, but system doesn't see it)
I'm assuming this means the drive has failed. Has it failed?
If it has failed, I need to replace. Can I simply buy a larger drive or do I have to replace the drive with the same 750GB drive? I would like to replace with a larger drive lets say 1 or 2TB... resync the mirror. Then replace the working 750GB with an identical drive to the replaced one. Can I do this? How? I do not want to lose the data on my still working 750GB drive.
"I'm assuming this means the drive has failed. Has it failed?"
Most likely, however, certain physical or software bugs can prevent it from resynching and/or being recognized ... you "could" reseat the drive and test it with diagnostics to be sure, but there is a very good chance the drive is simply bad and needs to be replaced.
A replacement drive must only be AT LEAST as large as the original - can be larger.
Replacing each drive one at a time as you describe will not "net" you anything ... you will still have a 750GB RAID 1 with no way to automatically or manually increase it to the full capacity of the disks - this would require a backup/restore.