DIsk sharing: is it possible without MC/SG?

[Enrico Venturi]

Hello colleagues!
Ok, don't kill me if I had a new idea to save some moneys: I'd like to make a cluster without using MC/SG. Nevertheless I want to use the disk sharing, for instance by using VA 71xx.
My question is: can I "mount/dismount" the volume groups (or the LUN's) by the HP-UX commands? or by the VA SDM? In few words: without using service guard ...

thanks
bye

[Chuck J]

You might be able to achieve this using NFS

Chuck J

[John Palmer]

Yes you can. Serviceguard uses 'HP-UX commands' to do this sort of thing in any case.

As far as LVM is concerned, about the only thing that you can't do without Serviceguard is vgchange -a e i.e. activate a VG in exclusive mode.

Regards,
John

[Enrico Venturi]

Chuck,
I appreciated your reply but by using NFS it's needed a "master node" which mounts the disk and exports it to everyone.
If the master node fails (disaster) nobody is able to manage the disk and to export its data.

[Enrico Venturi]

John,
thanks for your advice: as far as I know vgchange itself is available just by using MC/SG. Did you mean that without MC/SG the command is still available even if without some option or it isn't available at all?
And in the second hypothesis, can I do everything without the vgchange?

[Justo Exposito]

Hi Enrico,

From the vgchange man page:
NAME
vgchange - set LVM volume group availability

SYNOPSIS
Activate volume group
/usr/sbin/vgchange -a availability [-l] [-p] [-q quorum] [-s] [-P
resync_daemon_count] [vg_name...]

Assign to high availability cluster and mark volume group sharable
/usr/sbin/vgchange -c cluster -S sharable vg_name

Remarks
MC/ServiceGuard cluster operations require the installation of the
optional MC/ServiceGuard software, which is not included in the
standard HP-UX operating system.

Lock Manager cluster operations require the installation MC/LockManager
software which is not included with the standard HP-UX operating
system.

Mirrored disk operations require the installation of the optional HP
MirrorDisk/UX software, which is not included in the standard HP-UX
operating system.

DESCRIPTION
The vgchange command with the -a option activates or deactivates one
or more volume groups.

Regards,

Justo.

[Enrico Venturi]

Justo,
so you mean that the vgchange is always available in the HP-UX ... none of its options are available just in MC/SG environment.
Therefore MC/SG isn't required.
Or not?

[John Palmer]

Without Servicegurad, the ability to activate a VG exclusively is not available. This means that there's nothing to prevent you activating a VG simultaneously on more than one server, mounting filesystems and cusing corruption.

A lot of what you pay for with Serviceguard is mechanisms to prevent this sort of thing from happening.

Regards,
John

[Justo Exposito · Accepted solution]

Hi Enrico,

Yes, This man page is from a box without MC/SG software installed.
$ whereis vgchange
vgchange: /usr/sbin/vgchange /sbin/vgchange /usr/share/man/man1m.Z/vgchange.1m
$ cd /usr/sbin
$ ll vgchange
-r-sr-xr-x 31 root sys 561152 Sep 9 17:10 vgchange

As you can see vgchange command exists in this box but you can not use some parameters if you don't have MC/SG installed.

This is the output in a box with MC/SG installed:
HP4 #> whereis vgchange
vgchange: /usr/sbin/vgchange /sbin/vgchange /usr/share/man/man1m.Z/vgchange.1m
HP4 #> ll /usr/sbin/vgchange
-r-sr-xr-x 31 root sys 569344 Oct 10 2000 /usr/sbin/vgchange

Hope this help you,

Justo.

[Enrico Venturi]

just another question, still related to the same topic: how can I list all the available volume groups?

thanks again.