LVM and VXVM

[Mridul Dutta]

Hi , I m new in HPUX. i have seen in my office that they are using Lvm file system as well as VXVM . So can any body give some major diff between them .

Mridul

[Prashanth.D.S]

Hi Mridul,

Guess these two links will help you understand more about LVM and VXVM

http://docs.fc.hp.com/en/B2355-60105/lvm.7.html

http://docs.fc.hp.com/en/B7961-90025/ch01s02.html

Best Regards,
Prashanth

[Prashanth.D.S]

Hi Mridul,

Check this link which has a brief discription about the difference between LVM and VXVM

http://docs.fc.hp.com/en/5187-1372/ch01s02.html

Best Regards,
Prashanth

[Ralph Grothe]

LVM is a HP product and thus fully integrated in the OS.
Whereas VxVM is a Veritas/Symantec add on that (usually) requires an extra license.
VxVM is more feature rich and offers fuller control as far down as plex and subdisk level.
At the same this makes handling of VxVM (i.e. at the command line) more complicated because it has a sheer bewildering amount of commands and it lets you manipulate its objects in more than one ways.
Basically it has three modes of interacting,
1st the GUI tool vea, 2nd an interactive command user interface (e.g. vxdiskadm),
and 3rd the (scriptable) command line with dozens of vx* commands.
In my VxVM experience (which is from Solaris) rootability is trickier and more error-prone than LVM.
But recently I read in an HP-UX/VxVM doc that newer HP releases offer tools that convert LVM root disks to VxVM root disks (I think it was named lvmcp_vxvm), and in the restrictions I have only read that root, dump, and swap vols need to be contiguuous.
So maybe HP have handled it better for their OS than have SUN for Solaris.
With the latter for instance, once the volumes of the root disks have been encapsulated it is a rather difficult and involved procedure to change a volumes size (e.g. say you have set up a separate usrvol) which requires several reboots and juggling with different versions of the vfstab as well as the system file which loads Solaris kernel modules.
Therefore, I would resume
stay with LVM (or SDS or SVM on Solaris) for the root disks, and manage all your other disks with VxVM.
On the other hand this requires knowledge of two different volume managers with different design.
The most conspicuous difference is that LVM organizes disks in volume groups (VGs) whereas VxVM organizes them in disk groups (DGs).

[Jaime Bolanos Rojas.]

Mridul,

Also take a look at this thread, it will give you some more info,

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=666338&admit=-682735245+1156504679862+28353475

Regards,

Jaime.

[inventsekar_1]

LVM: Logical Volume Manager.

The wikipedia can give you good understanding:
http://en.wikipedia.org/wiki/Logical_volume_management

What is Logical Volume Management?
http://tldp.org/HOWTO/LVM-HOWTO/whatisvolman.html

this is a good page:
http://en.wikipedia.org/wiki/HP-UX

** "HP-UX was also among the first Unix systems to include a built-in logical volume manager. HP has had a long partnership with Veritas, and they use VxFS as their primary file system." **


VxVM: Veritas Volume Manager, VVM or VxVM :
The Veritas Volume Manager, VVM or VxVM is a proprietary logical volume manager from Veritas
http://en.wikipedia.org/wiki/VxVM

For simple understanding, u can take like this:
LVM is GOOD enough and simple to use.
VxVM is good for doing little complex (like online resizing, ...)operations than LVM.