Veritas Storage Foundation 5.1 SP1 Cluster File System Administrator"s Guide (5900-1738, April 2011)

shared device can be done concurrently from any host on which the cluster file
system is mounted. To be a cluster mount, a file system must be mounted using
the mount -o cluster option.
Cluster Services The group atomic broadcast (GAB) module in the SFCFS stack provides cluster
membership services to the file system. LLT provides kernel-to-kernel
communications and monitors network communications.
contiguous file A file in which data blocks are physically adjacent on the underlying media.
CVM (cluster volume
manager)
The cluster functionality of Veritas Volume Manager.
CVM Master The cluster volume manager has a master node that records changes to the volume
configuration.
data block A block that contains the actual data belonging to files and directories.
data synchronous
writes
A form of synchronous I/O that writes the file data to disk before the write returns,
but only marks the inode for later update. If the file size changes, the inode will
be written before the write returns. In this mode, the file data is guaranteed to be
on the disk before the write returns, but the inode modification times may be lost
if the system crashes.
defragmentation The process of reorganizing data on disk by making file data blocks physically
adjacent to reduce access times.
direct extent An extent that is referenced directly by an inode.
direct I/O An unbuffered form of I/O that bypasses the kernels buffering of data. With direct
I/O, the file system transfers data directly between the disk and the user-supplied
buffer.
discovered direct I/O Discovered Direct I/O behavior is similar to direct I/O and has the same alignment
constraints, except writes that allocate storage or extend the file size do not require
writing the inode changes before returning to the application.
encapsulation A process that converts existing partitions on a specified disk to volumes. If any
partitions contain file systems, /etc/fstab entries are modified so that the file
systems are mounted on volumes instead. Encapsulation is not applicable on some
systems.
extent A group of contiguous file system data blocks treated as a single unit. An extent
is defined by the address of the starting block and a length.
extent attribute A policy that determines how a file allocates extents.
external quotas file A quotas file (named quotas) must exist in the root directory of a file system for
quota-related commands to work.
Glossary202