lvextend HP-UX 11.0 (basic)

[James Pethigal_1]

I know this is a basic questions - but - I can't seem to find an answer in man or in the HP UX Admin guide:

Does lvextend in HPUX 11.0 preserve data integrity? I need to extend a LV by 4 GB that house a ERP application. Will in need to restore all the existing data on the LV after I extended it, or will it preserve/keep the data?

(granted - I will have full backups)

Thanks in advance,
James

[Vicente Sanchez_3]

Hi James,

When a lvol is extended, new space is added to the existing.

You don't need to restore/recover data to the lvol.

If the lvol is used as filesystem don't forget to extend it aswell (extendfs command).

You have to umount the filesystem if don't have JFS-Online installed and the filesystem is vxfs. If the filesystem is HFS you have to umount it.

Regards, Vicente.

[Ken Hubnik_2]

lvextend will not touch your existing data. It allocates new space the the logical volume so there is no need to restore/backup your data.

[James R. Ferguson]

Hi James:

Yes, as long as you are expanding a logical volume data will be prserved. It is when you shrink a logical volume (and its associated filesystem) that you need to backup and restore data unless you are dealing with OnlineJFS filesystems which can be shrunk dynamically without data loss. A backup, however, is always recommended before doing any kind of LVM maintenance.

Regards!

...JRF...

[S.K. Chan]

LVM is just like a "driver" between the FS and the disk drivers. So this means all it deals with is "virtual" disk space and does not access directly to the disk. Hence your suspicion .. LVM does not check for data integrity. However in an lvextend operation, the existing data is not "disturbed", it merely extend the virtual disk space that would map onto the physical disk space after you've run extendfs on the FS. So existing data would not be affected by this. Now if you're doing a lvreduce operation, a more cautious approach should be taken (eg: backup the FS first, etc, etc).