Chkdsk: before or after disk replacement?

[BatchFile]

Ok, I've just come in for a "couple of hours" to tidy up a bit and check things are working, and I've found that the SIMS (etc.) server has disappeared off the network.

 

Cause:It's got 3 HDDs, Raid 5: One is ok , One is working but with a SMART error , One has failed. and it had bluescreened and couldn't find anything to boot off as the RAID had been marked unusable. After resolving the "unusable" to "Degraded", I've replaced the failed one and it's currently rebuilding which will take about 12 hours.

 

The RAID is split into two partitions; one that boots, holds SIMS and Sage is ok, the other, which holds teacher filestores etc. is trashed and needs chkdisking at the very least, presumably because of the error on the "failing" disk, after the failed one had failed.

 

I've got the vast majority, of the data off the corrupt partition (though not all, due to an unrelated problem:rolleyes:) in a backup, which is currently being restored temporarily to a different server so I'm just after making things easier for myself here: once the dust has settled, should I replace the "failing" disk and THEN run chkdsk, or the other way round?

[SYNACK]

Chkdisk is a big hammer and will happilly cover over files it can't recover and 'clean' away all hint to their existence in file tables etc. I'd get the system as stable as possible before running it. Basicly what it can't save it will destroy, taking a raw image first may be a good call depending on how required the files are.