SAN partition with ext3 fs turns read only when shared bet two servers

[Ashay Chitnis <chitnis ashay gmail com>]

Dear All,

Scenario:

I am facing a unique issue as below.
I have two physical machines installed with a windows beta
virtualization env. on them. There is one centos 5.2 virtual server
running on each physical machine. There is a SAN (IBM) partition
provided to the virtualized servers by the host Windows OS on both
physical machines. The partition is formated in ext3  Both the
virtualized Centos servers are linked using heartbeat so that any of
the server goes down the other server will take on the resources
(Namely a floating IP and SAN storage) and start the services so that
there is minimal interruption in services during hardware failure of
one server. This is similar to heartbeat with drbd sans drbd. We have
imap user data mounted on the system as since we had  a SAN storage
didnt opt for internal Storage or drbd structure.

Graphical Representation is attached for elaboration.

Problem:
The problem is that during the fail over testings we found that the
ext3 partition became read only during transition from one server to
other server.  What i want to know is

1. if attached scenario is feasible where in during failover occurs
the other server mounts the SAN storage and mailbox server is available
at all time.
2. What happens when one server has network issue but
has not unmounted the SAN ? Is this the case why probably my partition
becomes read only?

regards,
Ashay.

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