Veritas File System v5.0.1 Administrator's Guide for HP-UX 11i v3 (5900-0082, June 2010)

■ Holes in sparse files require no storage and are eliminated by typed records.
A hole is determined by adding the offset and length of a descriptor and
comparing the result with the offset of the next record.
■ While there are no limits on the levels of indirection, lower levels are expected
in this format since data extents have variable lengths.
■ This format uses a type indicator that determines its record format and content
and accommodates new requirements and functionality for future types.
The current typed format is used on regular files and directories only when
indirection is needed. Typed records are longer than the previous format and
require less direct entries in the inode. Newly created files start out using the old
format, which allows for ten direct extents in the inode. The inode's block map is
converted to the typed format when indirection is needed to offer the advantages
of both formats.
Extent attributes
VxFS allocates disk space to files in groups of one or more extents. VxFS also
allows applications to control some aspects of the extent allocation. Extent
attributes are the extent allocation policies associated with a file.
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.
See the setext(1M) and getext(1M) manual pages.
The vxtunefs command allows the administrator to set or view the default indirect
data extent size of a file system.
See the vxtunefs(1M) manual page.
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 provides fast recovery
with the VxFS intent log and VxFS intent log resizing features.
VxFS intent log
VxFS reduces system failure recovery times 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. The intent log recovery feature is not readily apparent to
users or a system administrator except during a system failure. During system
Introducing Veritas File System
Veritas File System features
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