Sunday, 8 April 2018

How to Hot-Remove a Disk Shelf in ONTAP 8.2.1 or Later (in Pictures)

I’ve had to do a few of these, and whilst the official documentation is perfectly excellent for the job, there’s no illustrations, and I have a mind that likes to visualize things (I think many people like visualization). So, whilst I was waiting for a shelf hot-removal job to start (I’d arrived on site an hour early), I did some Visio diagrams. For the official documentation read here and here. You can remove a shelf from anywhere in the stack (first, middle, last), most commonly it is the last shelf in the stack that is removed so we illustrate that here. It’s essentially just a simple 4 step process (4 cables to move).

0) Pre-requisites

i: Data ONTAP 8.2.1 or later.
ii: Disks multi-pathed - check each disk has an A and B path:

7-Mode::> storage show disk -p
(Clustered) ONTAP::> node run NODENAME storage show disk -p

iii: Remove all aggregates from the disks in the shelves you are removing.
iv: Remove disk drive ownership from the disks in the shelves you are removing.
v: If it is a HA-pair, neither system can be in a takeover state.

Image 0: FAS2552A (our example system) with 3 external shelves and MPHA SAS cabling

1) Remove the A-Path shelf to shelf connecting cable

Before starting send AutoSupports.
Remove the A-Path last shelf square to previous shelf circle connecting cable (cable in yellow below).

Image 1: Remove the A-Path shelf-shelf connecting cable

2) Move the A-Path circle cable to the new last shelf

Move the A-Path (long) circle cable to the new last shelf (dashed red cable below).
Run storage show disk -p until each node no longer sees an A-path to the removed shelf.

Image 2: Move the A-Path circle cable to the new last shelf

3) Remove the B-Path shelf to shelf connecting cable

Remove the B-Path last shelf square to previous shelf circle connecting cable (cable in yellow below).

Image 3: Remove the B-Path shelf-shelf connecting cable

4) Move the B-Path circle cable to the new last shelf

Move the B-Path (long) circle cable to the new last shelf (dashed blue cable below).
Run storage show disk -p until each node no longer sees a B-path to the removed shelf.

If you have out-of-band ACP cabling, re-cable the ACP.
Check ACP status (storage shelf acp show).

We can then power off and physically remove the shelf to be removed.
Finish by sending AutoSupports.

Image 4: Move the B-Path circle cable to the new last shelf

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