From: Greinig, Peter (Peter.Greinig@bourne-leisure.co.uk)
Date: Thu Nov 28 2002 - 05:00:32 EST
Hi All,
We have 3 DEC Alpha machines, NOT clustered, running DU 5.1, with an
attached SAN comprising 2xHSG80 & several shelves of disk.
Disks are split between the three machines, i.e. the visibility of each
storageset in the SAN is restricted to one of the three nodes.
However, we do have a single storageset which is deliberately made available
to all three nodes. Each node has the same mount point & entry in
/etc/fdmns. This allows, for example, a complete database unload to be made
to this disk, then the disk can be unmounted & re-mounted on another machine
(e.g. transfer from production to development) without having to copy huge
amounts of data across the network.
This setup works fine.
What worries me is that I accidentally mounted the disk on TWO machines
yesterday - I realised I had done it BEFORE writing anything to the disk,
but I presume there is some danger of complete disk corruption if I had done
anything. The disk has an advfs filesystem on it.
What I wonder is:
1. What the dangers (if any???) are of having this disk mounted on two
effectively unrelated systems - I could see advfs getting itself in a
complete mess, but don't know for sure.
2. What controls I can add to make sure that I can't mount this disk on more
than one node at once - I am suprised that there isn't something written to
the disk header (label?) which shows that an advfs filesystem is currently
mounted.
Thanks for any help, will summarise (if the systems are still running!!!),
Peter.
Peter Greinig,
Systems Programmer
Bourne Leisure Group Ltd
email: peter.greinig 'at' bourne-leisure.co.uk
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