We are going to be adding an additional FC shelf to our clustered F740's. Obviously, the safe way to do this is to halt both 740's, attach the A & B loops, then bring both filers back up.
But, what I was wonder was, would it be possible to:
- Attach the B-loop first. - Have the B-Loop Filer take over all th shelves (including the new shelf). - Attach the A-Loop. - Give back the shelves to the A-Loop filer.
I don't think we'll do this as we're only talking about about maybe 2 minutes of downtime vs 30 seconds, but I was wondering if this is a feasible thing to do.
Thoughts?
j.
"Jay" == Jay Soffian jay@cimedia.com writes:
Jay> We are going to be adding an additional FC shelf to our Jay> clustered F740's. Obviously, the safe way to do this is to Jay> halt both 740's, attach the A & B loops, then bring both Jay> filers back up.
Jay> But, what I was wonder was, would it be possible to:
Jay> - Attach the B-loop first. - Have the B-Loop Filer take over Jay> all th shelves (including the new shelf). - Attach the Jay> A-Loop. - Give back the shelves to the A-Loop filer.
After talking with Steven Watanabe, a member of NetApp's cluster group, we arrived at the following recipe. It was also pointed out to me that this is documented in the "Fibre Channel StorageShelf Hardware Guide" in the section titled "Adding disk shelves to a cluster".
Our two filers are Subzero and Viking. They each have 3 shelves, with ID's 1 2 and 3. We will be adding the new shelf to the end of Subzero's FC-AL loop as shelf ID 4.
Procedure:
1) Login to viking, cf takeover. 2) Viking takes over subzero's shelves, so it now runs its 3 shelves on loop A and subzero's 3 shelves on loop B. At this point, subzero will reboot to "Waiting for giveback...". 3) Power off subzero. 4) Break subzero's A-loop and attach it to the new shelf, being careful NOT TO TOUCH viking's B-LOOP. 5) Power on subzero. Since viking will still be in takeover mode, subzero will attempt to boot but end up "Waiting for giveback...". 6) On viking, cf giveback. 7) Wait for giveback to complete. 8) On subzero, cf takeover. 9) Subzero takes over viking's shelves, so it now runs its 4 shelves on loop A and viking's 3 shelves on loop B. Viking will reboot to "Waiting for giveback...". 10) Power off viking. 11) Break viking's B-loop and attach it to the new shelf. 12) Power on viking. Since subzero will still be in takeover mode, viking will attempt to boot, but end up "Waiting for giveback...". 13) On subzero, cf giveback.
We'll be performing this maintenence on Sunday, so I'll let toasters know how it turns out.
Much thanks to Steven for providing this information.
j. -- Jay Soffian jay@cimedia.com UNIX Systems Engineer 404.572.1941 Cox Interactive Media
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Jay Soffian