Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Planning a Workgroup
Planning to Manage File Systems
Chapter 288
• As of 10.20, HP-UX allowed JFS as a local root file system within a
logical volume, although not on a non-partitioned, whole disk. The
10.20 implementation of JFS is VERITAS Version 3, which supports
file sizes greater than 2 GB as well as large user identification
numbers (UIDs). See vxupgrade (1M) for information to convert a
Version 2 file system to Version 3. You are not restricted to using only
a single version on your system; however, you cannot mount Version
3 on a 10.01 system.
• As of 10.30, JFS became the default file system for Instantly Ignited
and cold installed servers.
• HP-UX 11i version 1 includes JFS 3.3 or 3.5, which supports Access
Control Lists (ACLs) and disk layout Version 4, among other
features. HP-UX 11.00 includes JFS 3.1, but JFS 3.3 is available for
HP-UX 11.00 from the HP Software Depot,
http://software.hp.com.
JFS and other File Systems
How does the journaled file system (JFS) compare to HFS?
JFS improves upon the High-Performance file system (HFS) in the
following ways:
• faster recovery time versus HFS fsck, by using an intent log
• more robust than HFS, because JFS contains more panic avoidance
code
• better performance under many circumstances, due to use of extents
• online administration, including backups, resizing, and
defragmentation, using the optional HP OnLineJFS package
As compared to HFS, JFS recovers much faster from system failure, due
to its mechanism for logging changes to the file-system structure. When
the system boots after a crash, the file system synchronizes using its log
to speed recovery, in an operation similar to, but much faster than, that
performed by fsck. Fast recovery time is particularly useful in
environments that require high performance or that deal with large
volumes of data.
JFS allows for higher data throughput (faster I/O) than HFS. This is due
to the JFS organization of file storage into extents, which can consist of
multiple data blocks.