3.1.2 MxFS-Linux Administration Guide

Chapter 1: Introduction 2

• Incremental NFS Server scalability. New physical NFS servers can be

added to an existing file-serving cluster to serve the same filesystems

for a set of new clients without disturbing the connectivity and

operation of other NFS clients and servers that may be sharing those

filesystems.

• High availability for NFS clients. MxFS supports continuous NFS

client operation across a hardware or software failure that inhibits

NFS service from a given cluster server. Because another cluster server

inherits the same IP address used for the NFS client-server

connections, the clients will continue NFS operation to that same IP

address via a different physical server.

The server inheriting the IP address and associated NFS clients may

also be an NFS server serving a pre-existing set of NFS clients. These

pre-existing clients will not experience any interruption or delay when

the new NFS clients transition to the server. (Only the transitioning

subset of NFS clients, and not the pre-existing clients, are subject to the

lock-recovery grace period and other transitional delays.) The

transitioning subset of clients are shielded from transient errors that

may be caused by the failure that induced the transition.

• Cluster-wide NFS client lock coherency. MxFS supports mutual

exclusion with file and byte-range locks used by multiple NFS clients

connected to separate NFS servers exporting the same filesystem(s).

Note, however, that file locks via NFS are disabled by default. Explicit

administrative action is required to enable file locking via NFS. See

“Using the NLM Protocol” on page 44 for more information.

• NFS client lock re-acquisition on server failover. When a group of

NFS clients fail over to another NFS server, any file or byte-range locks

held by those clients are released and then automatically re-acquired

after the clients have successfully transitioned to another server.

• Group migration of NFS clients. The administrator can gracefully

migrate an NFS service and the associated NFS clients from one server

to another for maintenance or load-balancing purposes, without

downtime or failure of any NFS client.