Veritas Storage Foundation 5.1 SP1 Cluster File System Administrator"s Guide (5900-1738, April 2011)
the old master/slave or primary/secondary concept. The first server to mount
each cluster file system becomes its primary; all other nodes in the cluster become
secondaries. Applications access the user data in files directly from the server on
which they are running. Each SFCFS node has its own intent log. File system
operations, such as allocating or deleting files, can originate from any node in the
cluster.
About Storage Foundation Cluster File System primary/secondary
failover
If the server on which the SFCFS primary is running fails, the remaining cluster
nodes elect a new primary. The new primary reads the intent log of the old primary
and completes any metadata updates that were in process at the time of the failure.
If a server on which an SFCFS secondary is running fails, the primary reads the
intent log of the failed secondary and completes any metadata updates that were
in process at the time of the failure.
About single-host file system semantics using Group Lock Manager
SFCFS uses the Veritas Group Lock Manager (GLM) to reproduce UNIX single-host
file system semantics in clusters. This is most important in write behavior. UNIX
file systems make writes appear to be atomic. This means that when an application
writes a stream of data to a file, any subsequent application that reads from the
same area of the file retrieves the new data, even if it has been cached by the file
system and not yet written to disk. Applications can never retrieve stale data, or
partial results from a previous write.
To reproduce single-host write semantics, system caches must be kept coherent
and each must instantly reflect any updates to cached data, regardless of the
cluster node from which they originate. GLM locks a file so that no other node in
the cluster can update it simultaneously, or read it before the update is complete.
About Veritas File System features supported in
cluster file systems
The Veritas Storage Foundation Cluster File System is based on the Veritas File
System (VxFS).
Most of the major features of VxFS local file systems are available on cluster file
systems, including the following features:
■ Extent-based space management that maps files up to a terabyte in size
Technical overview of Storage Foundation Cluster File System
About Veritas File System features supported in cluster file systems
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