Disk Swapping & Volume Groups

[S Feltrogh]

I'm currently maintaining a system that uses a HP workstation (HP-UX 10.20) and an external disk silo. The philosophy is that the silo contains an external hard disk that can be swapped depending on which training database is required. Currently this works OK, and the WS will boot up correctly no matter which external disk is used.

My problem is that I have to create another external disk for the system. I can get the workstation to either boot up to recognise the vg on the new external disk (when the vg was created on that disk), or on the existing disks (using an imported vg). When I try swapping the disks in either case, I get a message about how the device (the same device name is used for all the external disks) could not be accessed and the quorum was not met. Even when the 9GB disk is configured in the same way as the others (eg same size of LV, etc) the problem occurs.

Any help or advice would be much appreciated.

Thank you,
S.



The new disk is 9GB, the others are all 4GB - is this scheme feasible, and if so, what do I need to do to ensure that the WS boots up and recognises vg01 (the vg for the external disk) regardless of which is used?

[Dietmar Konermann]

Hi!

I believe that /etc/lvmtab is responsible for your problem. It does not only contain the path names of the VG directory and the PV device special files... it also contains the the VGID which is unique for for each VG.

Assuming this reason a vgscan or a vgexport/vgimport should help to get the lvmtab updated.

Regards...
Dietmar.

[Stefan Farrelly]

Your message is a little confusing to me. I dont understand why you get a quorum error if you have only a single disk in vg01. Is this correct?

In any case, if you simply vgimport each time then your creating vg01 from scratch, and importing a single disk to it which will work fine. (I would use vgimport each time you swap) and when you swap while the workstation is up and running then do an ioscan -f each time you swap the disk - so the kernel picks up that you may have now changed from a 4Gb drive to a 9 or vice versa. I think your system is getting a little confused because your using the same device file for different size disks or different disks but vgimport should get around this.

[S Feltrogh]

Hi,

Sorry if this sounds confusing! Yes there is a quorum error reported when the vg contains a single disk. If I have a vg compatible with the existing disks, I get the could not access / quorum error with the new disk, and vice versa.

Is it possible to "seamlessly" swap out disks of different sizes, without running vgimport? Although I know a bit of unix I have only recently started using HP-UX and vgs are still a bit of a mystery to me. The users of the system are not experts in HP-UX either and would prefer to keep things simple!

Thanks for your help so far,
S.