Veritas 4.1 Installation Guide (HP-UX 11i v3, February 2007)

mission-critical applications, where high availability is required. It increases I/O and provides
structural integrity.
The Veritas File System version 4.1 (VxFS 4.1) is the vxfs file system for HP-UX 11i Version 3
release.
VxFS Features
VxFS has the following features:
• Extent-based Allocation
An extent is defined as one or more adjacent blocks of data within the file system. VxFS
allocates storage in groups of extents rather than a block at a time thereby resulting in faster
read-write operations.
• Extent Attributes
Extent attributes are the extent allocation policies associated with a file. VxFS allocates disk
space to files in groups of one or more extents. VxFS allows applications to control extent
allocation.
The setext and getext commands allow the administrator to set or view extent attributes
associated with a file, as well as to preallocate space for a file.
• Fast File System Recovery
Most file systems rely on full structural verification by the fsck utility as the only means
to recover from a system failure. For large disk configurations, this involves a time-consuming
process of checking the entire structure, verifying that the file system is intact, and correcting
any inconsistencies.
VxFS reduces system failure recovery time by tracking file system activity in the VxFS intent
log. This feature records pending changes to the file system structure in a circular intent log.
• Access Control Lists (ACLs)
An Access Control List (ACL) stores a series of entries that identify specific users or groups
and their access privileges for a directory or file. VxFS supports up to 1024 ACLs on HP-UX
11i Version 3.
• Online Administration
A VxFS file system can be defragmented and resized while it remains online and available
to users. The online administrations operations supported are backup, resizing and
defragmentation.
• File Snapshot
VxFS provides online data backup using the snapshot feature. An image of a mounted file
system instantly becomes an exact read-only copy of the file system at a specific point in
time. The original file system is called the snapped file system and the copy is called the
snapshot.
• Expanded Application Interface
VxFS provides following specific features for commercial applications:
— Pre-allocating space for a files
— Specifying fixed extent size for a files
— Bypassing the system buffer cache for file I/O.
— Specifying the expected access pattern for a file.
18 Product Overview