/etc/lvmpvg & /etc/lvmtab

[Lor]

Gentlemen,
Just for curiosity.

Running HP-UX 10.20 on different LVM configured servers, I find the following :

- on some servers, /etc/lvmpvg file exists
but is is empty :-(

- on other servers, it doesn't exist at all (?)

On all these servers disks are under LVM management and everything works fine.

For my understanding,

- what is the difference between /etc/lvmtab and /etc/lvmpvg ?
man on lvmpvg says it is supposed to hold information on physical LVM mapping (To my understanding this is /etc/lvmtab role)

- how to explain the existance (or not) of
the /etc/lvmpvg file

Thank you.

Hugues

[Vince Inman · Accepted solution]

The /etc/lvmtab is basically LVM's database of what has been config'd using LVM, it is ritical to the proper functioning of LVM.

The /etc/lvmpvg is nothing more than a flat file which can be used to segregate physical volumes WITHIN a volume group. As an example, I always create a PVGs for the root vg with two PVG's; one for the root primary and another for the root mirror. This prevents problems like mirroring a LV to the same disk where the primary exists.

The /etc/lvmpvg file has absolutely no bearing on the functionality of LVM whereas the /etc/lvmtab is critical.

[Cheryl Griffin]

This file is not required for LVM unless you are using physical volume (PV) strict allocation.

See the man page for vgcreate.

[Stefan Farrelly]

/etc/lvmtab
is like /etc/fstab, a list of all VGs and disks in each one. do a strings /etc/lvmtab to see them all in a nice format.

/etc/lvmpvg
is for lvols created using the -D (distributed) option which allows you to place lvols/striped lvols/mirrors on certain lvm groups (which have specific disks in them)

[Doug Sperle]

You can force the creation of the /etc/lvmtab file by typing vgscan -av as root.