Renaming a directory in a mount point path in a shared disk scenario.

[P_F]

Just want to make sure I've thought this through correctly before executing:

SCENARIO:

Between 2 HP machines (primary and secondary node) I've got a san. There is an exported volume group between these to machines, on the shared disk of the san.

There is a mount point similiar to this(/etc/fstab):

/dev/some_vg/some_lv14 /some_dir/pXX/another_dir vxfs rw,suid,largefiles,delaylog,datainlog 0 2

I wish to change the directory name from "pXX from "pYY"

I'm pretty sure I can do it like this:

STEP (1)
umount /some_dir/pXX/another_dir
(on both nodes)

STEP (2)
cd /some_dir
mv pXX pYY
(on the primary node ONLY)


STEP (3)
Change the fstab on BOTH nodes to reflect the new directory name

STEP (4)
re-mount.


Note: there was no renaming (mv) of the directory name on the secondary node.

[Duncan Edmonstone]

Are you saying this same volume group is active on both nodes and an LV in the volume group is mounted on both nodes? You do know this is only supported if you are using the Serviceguard Cluster Filesystem

Looking wat what you've shown us there you aren't as the Serviceguard Cluster Filesystem only works with VxVM not LVM.

If you only have it mounted on one node at a time, your steps look OK to me.

HTH

Duncan

[P_F]

Thanks for the response.

> Are you saying this same volume group is active on both nodes and an LV in the volume group is mounted on both nodes?

Yes.

> You do know this is only supported if you are using the Serviceguard Cluster Filesystem

Yes. This is what we are using. It is a service guard RAC machine, 2 node.


> If you only have it mounted on one node at a time, your steps look OK to me.

Well, I guess it will be mounted since this particular VG is SGeRAC.

[Duncan Edmonstone]

So its SGeRAC, but is is SGeRAC with the Serviceguard Storage Management Suite Cluster Filesystem? So is the Volume Manager VxVM rather than LVM. SLVM used with SGeRAC allows you to have a LVM volume group active on 2 nodes at once, but it does *not* allow you to have a filesystem mounted on 2 nodes at once (it won't stop you doing it, but i'ts not supported). SLVM is for raw Oracle partitions only.

The only way to have a filesystem mounted on 2 nodes at once is with the Cluster Filesystem option, and that uses the clustered version of VxVM.

Sorry to be pedantic here, but if your current config isn't a supported one, I wouldn't want to suggest any changes at all yet...

HTH

Duncan

[P_F]

> is it SGeRAC with the Serviceguard Storage Management Suite Cluster Filesystem?

No. We are raw. Maybe ASM in the future.

Thanks for clarifying these points.

[Duncan Edmonstone]

So although you can mount the filesystem on both nodes, as each are not aware of the others buffer cache, or file locking semantics, there's no way for them to manage concurrent access to the filesystems. The upshot is that you risk filesystem corruption if you do this. What are you using the filesystem for? Oracle binaries? Archive logs? something else?

HTH

Duncan

[P_F]

> The upshot is that you risk filesystem corruption if you do this. What are you using the filesystem for? Oracle binaries? Archive logs? something else?

This WILL contain raw data files.

Right now, there is no live production data on this filesystem, since the machine is still being configured for future production use.

Are you saying there is a risk beyond data corruption, that is the filesystem itself might become corrupt?

[P_F]

Oh, yes. Sorry I didn't pick up your point.

Yes, the root mount point is ONLY mounted on 1 node in the cluster.

[Duncan Edmonstone]

Hmm I think we may be confusing each other now!

>> This WILL contain raw data files.

But if it contains raw Oracle data files, it won't be on a filesystem?

A cooked oracle datafile might look like:

/oracle/u03/oradata/SID/mydata01.dbf

That's on a filesystem and can't be concurrently mounted between hosts.

A raw oracle datafile might look like this:

/dev/vgORA03/rlvol_mydata01

And with SGeRAC over SLVM that would be accessed concurrently from both hosts (not MOUNTED of course cos its not a filesystem)

But you are talking about moving a filesystem which is mounted from both hosts...

So I'm confused...

HTH

Duncan