The location of the HD's can be different Don depending if the processors are DSCXLV2, or V2+.
* The V2+'s had a HD on each processor board in an accessible disk bay, and then the raided disc on the disc plate connected to CCA with the eSATA cable.
* The earlier DSCXLV2's, CCA had a ribbon cable from the processor to two HD's on the disc plate, both of which were easy to change (disc bay). CCB had the HD mounted inside it, screwed on the board - not ideal for hot swap. So you can't tell from the original post which type they have.
By mentioning HDb, I am assuming he's on CCA ("single processor" also confirms CCA too!
) and one of the two raided discs is bad, most likely the one on the disc plate if it's DSCXLV2+ although you can't be sure. But, the working one will be flashing like a christmas tree, and the dead one will either not be flashing at all, or very occasionaly. So I would also use that as an indication of which disc to change.
I would check the status of the HD's in the portal, and if 'create recovery hd' button is available, I'd click it, because it will try to stop the raid if it has not already stopped.
Then I would slide out the HD's and replace, give it a minute, and try to restart the raid through portal.
If you take out the wrong HD, if you take out HDa and HDb is the bad one, then if the system is functioning normally it's no great problem, it will make a switchover if CCA was (telephony) Active, or if CCB was active, users won't notice. ADP will restart on B if it was running on A. If they have OSCC then CSTA reboot is a consideration.
Also, you should only use HD's listed as supported in the release note. If you using something else, good behaviour is not guaranteed.
For V6 R2.17, supported HDs are
Seagate ST9250410AS
Toshiba MK2576GSXZ
Toshiba MK2561GSYB
