Replace a disk without powering off the box

[neuralnode]

Hi there all,

As in the title of this post: Is it possible to replace a disk in a RS/6000 box without actually powering off the machine?

Suppose rootvg is mirrored over two physical volumes, hdisk0 and hdisk1. At some point hdisk1 fails, so we want to replace it with a new disk. What I'd do in such a case, I'd (1) unmirror the faulty disk, (2) reduce it from rootvg, (3) remove it from ODM (rmdev), and physically replace it with a new empty disk. I'd then run cfgmgr, add the new disk to rootvg, and mirror rootvg. Normally, you'd need to shutdown the machine while physically replacing the disks, but do you think it is possible (and safe) to conduct the entire procedure on a live system?

Thanks in advance.
Rgds.

 

[RMGBELGIUM]

It all depends on what type of hardware you have.I have done it on a P520 online,worked as designed.No guarantees for older hardware ...

 

[p5wizard]

If the hardware supports it and you use the correct diag dialogues, yes it is possible.

On older hardware, with real power and signal cables going to a SCSI disk, I would not recommend it and note that IBM Customer Engineers won't do stuff that isn't approved/tested by IBM.

But I will admit I have done so in the past when a maintenance window was not foreseen in the near future and I wanted to replace a disk badly.

BUT... a) on non-hotplug hardware you can really mess up the machine especially if a SCSI terminator gets disconnected in the process (even for just a short while)... b) it is really hard to know which disk is which if you can't look at the address jumpers, so beforehand you'd want to label the SCSI address somewhere visible without having to nearly completely dismantle (and stop) the server... c) wait for the disk to spin down after rmdev-ing it and d) disconnect power to the disk first, before disconnecting the SCSI cable.

Disclaimer: This info is not exhaustive so don't even try doing this kind of operation if you don't know what you're doing...


HTH,

p5wizard

 

[TSch]

Right, if your disks are hot-plugable there shouldn't be any problem.

Replacing such disks without powering off has become a standard procedure in our company and we never had any problems.

EMC technicians will do this and IBM technicians as well as long as the disks are officially declared as hot-plugable ...

But: Also right -> I wouldn't advise you to do this with scsi disks ...

Regards
Thomas