REPLACING OS DISKS WITH LARGER DISKS

[frederick hannah]

I am upgrading OS disks from 18GB to 36GB capacity. Is there a document that would cover such procedures. I intend to replace one disk at a time, treating each larger disk as a boot disk to be included in vg00. Would those "mirrored boot disk" procedures work?

[James R. Ferguson]

Hi Frederick:

While you can certainly replace an 18GB disk with a 36GB one, it is possible that you will not be able to use all of the new disk if you simply use mirroring to replicate your data to it.

The reason is that anytime you 'vgextend' a volume group, the LVM header information laid down during the original 'vgcreate' is replicated. Thus if the original disk had been created with a 'max_pe' or 'pe_size' that accomodated 18GB but could not accomodate 36GB, your new, larger disk could not be used to its full potential.

Since you are dealing with vg00, I suggest that you create an Ignite recovery image of your existing vg00 and reinstall to a 36GB disk. THen, 'vgextend' the second 36GB disk into the volume group and, lastly, mirror all of the logical volumes comprising vg00.

Regards!

...JRF...

[frederick hannah]

"Vgdisplay vg00" indicated my PE size as 8 and MAX PE PER PV as 4350. Wouldnt those settings allow for most of the 36GB disks to be used?

[Patrick Wallek]

Yes, that would allow you to use most of the disk.

8 MB x 4350 PEs = 34800 MB as the maximum you'll be able to access in the VG. That should cover you pretty well.

[James R. Ferguson]

Hi (again):

Yes, given a 'pe_size' = 8 and a 'max_pe' = 4350, you should have nearly all of the use of a 36GB disk --- enough to not make a re-Ignite worthwhile.

Most of the space on a physical disk comprising vg00 is "wasted" anyway, assumeing that you confine vg00 to *only* the stardard HP-UX logical volumes and a reasonable size primary swap.

Regards!

...JRF...

[frederick hannah]

Thanks for help!!

[frederick hannah]

Thanks for the help!!

[frederick hannah]

sorry, new at this. again, thanks