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Re: FC10 - Mirror, bad disk

 
Cathy Nooning
New Member

FC10 - Mirror, bad disk

We have an a K-class server running hpux 11.0 that is using 2-FC10s. The 2nd FC10 is used to mirror the first. Twice now we have had a disk go bad on the primary mirror. In both cases the system became unusable and the system was then rebooted. Each time the system failed to completely boot. As when it went to activate the volume group with the bad disk it hung there.
I would not expect a bad disk to cause an outage. I would have thought that we could have split the mirror, replaced the disk (they are hardware hotswapable). I would then expect that we could simply perform a pvcreate on the replaced disk and resync the mirror.
Does the fact that a system quits performing because of a bad disk sound wrong? My past experience has always been that a bad mirror does not cause a system to become unusable.
3 REPLIES 3
James R. Ferguson
Acclaimed Contributor

Re: FC10 - Mirror, bad disk

Hi Cathy:

This sounds like a disk quorum problem -- you hadn't specified "low quorum" when the boot disk was established, and hence "paid-the-piper" when you least wanted to do so.

As document #KBAN00000036 notes, "mirroring does provide extra copies of essential root filesystem data but does not necessarily provide an alternate boot disk and does not provide 'failover'.

Have a close look at this document. I think it will help you understand what happened and prevent, at least, some of the same problems in the future.

...JRF...
John Waller
Esteemed Contributor

Re: FC10 - Mirror, bad disk

Cathy, I agree this does not sound correct. Even though you have not said I presume that the disk is not part of vg00 but a data volume group. If this is the case then you should not have any problems in loosing a disk, whether it was the primary or second disk. I personally would look at the patch level of the system. I know their are a number of LVM patches for HP-UX 11.00. Another thing to possibly check is your fibre connecton. Are you using a fibre hub? Running the FC10 in single or split bus mode? It may seem silly but are you sure you are mirrored to 2 seperate disks. I have seen an example where the user thought he was mirroring but he had 2 paths to the same disk. Good luck.
Cathy Nooning
New Member

Re: FC10 - Mirror, bad disk

Thanks for the replies. It was not root, which made it all the more confusing. I am in the process of checking the patches right now.
Thanks again