enquiry regarding LVM

[Deepak kumar_3]

Hi,

I feel in Open VMS Logical volume manager
(unix LVM) is nothing but volume set ie
using mount/bind command we can achive the
same functionlity of unix LVM or its
something else.
Please give the suggestion.

Deepak

[Uwe Zessin]

OpenVMS does not really have a logical volume manager implemented. An LVM like that from HP-UX or Linux is nothing but an implementation of host-based virtualization. You take multiple disks (PVs - physical volumes) and bind them together to a VG - volume group. Out of this VG you 'cut' the LVs (logical volumes) where the file system is stored.

The virtualization layer allows you to put additional PVs into the VG or expand LVs as long as there is enough space in the VG.

An OpenVMS 'multivolumne set' is nothing but a set of disks that are loosely coupled through the entries in the root (=first) volume. Each disk still looks like a normal ODS structured volume with only minor differences (e.g. there is now data in VOLSET.SYS). You can expand the volume set by binding an additional disk drive to the whole set, but that's it.

One might be able to simulate an LVM through the use of the (extra cost) host-based RAID software, but last time I checked it works with normal files on the underlying disks (not necessarily bad).

[Ian Miller.]

depends what unix LVM does. If it creates stripe sets for example then the equivilent is the VMS host based RAID software.
http://h71000.www7.hp.com/openvms/storage/raidpage.html

[Mobeen_1]

Deepak,
Is your question .. "Is there any LVM in OpenVMS".

If that is your question, then something that comes quite close to LVM is as Ian has mentioned the raid implementation.

Otherwise, its only physical volumes.

regards
Mobeen

[Anton van Ruitenbeek]

Deepak,

Are you seeking for LVM or HBVS. As far as I can recall is LVM the implementation of Host Based Volume Shadowing on Tru64.
In this case VMS has volumeshadowing (License: VOLSHAD) . Works very good for non interuptable systems. 20 years old, so very stable. We are using this (as also the most banking systems etc.).

AvR

[Uwe Zessin]

LSM (Logical Storage Manager) on Tru64 Unix can do _way_ more than OpenVMS' HBVS - it is a terribly complicated beast.

HBVS is about 10 or 11 years old - it was first supported on VAX/VMS V5.4 on Fault-Tolerant VAX systems. V5.4-3 brought general support. Controller-based shadowing (VAX Volume Shadowing Phase 1), based on the HSC-50 storage controller came around 1987/88 - if I recall correctly - with VAX/VMS V4.4.

[Keith Parris]

I think the replies here have summarized things pretty well. There's no single product which does LVM on OpenVMS, but you can do basically the same functions with a set of products:

o Mirroring (RAID-1): Host-Based Volume Shadowing (HBVS) Software
o Striping (RAID-0): Host-based RAID Software
o RAID-5: Host-based RAID Software
o Partitioning: Host-based RAID Software
o Disk concatenation: Bound Volume Sets ($MOUNT/BIND)

Storage expansion (expanding a pool of storage) is presently only possible on OpenVMS down at the storage controller level, with Dynamic Volume Expansion (DVE) in OpenVMS supporting this function up at the OS level.

[Deepak kumar_3]

Hi All,

Thank you very much for giving all the information, now i have fairly good idea how and what to use in VMS.

Regards
Deepak

[Uwe Zessin]

Hello Deepak,
if that information was useful to you, please consider showing your appreciation by assigning a few points to the answers, thanks!

http://forums1.itrc.hp.com/service/forums/helptips.do?#28

[Deepak kumar_3]

Hi All,

Sorry i forgot to assign points, but
now i did.

Deepak