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

Planning a Workgroup
Planning to Manage File Systems
Chapter 2 89
The optional HP OnLineJFS product eases system maintenance by
allowing you to perform tasks such as file-system backup and enlarging
or reducing a file system without unmounting it. These capabilities are
not available on HFS.
• “Converting Existing File Systems to JFS” on page 644
What are the disadvantages of configuring a file system using JFS?
You might not want to configure JFS on a system with limited memory
because its memory requirements exceed those of HFS.
Is JFS use restricted in any way by LVM (see “The Logical Volume
Manager (LVM)” on page 558)?
You can use JFS on any file system, whether or not it is being managed
by LVM.
How is JFS administered?
JFS can be administered using SAM or HP-UX commands. SAM has
utilities to create (add), backup, and resize JFS file systems.
If you have the optional HP OnLineJFS package (referred to in some
manpages as Advanced VxFS), you can use the VxFS Maintenance menu
choice of SAM to view extent and directory fragmentation, reorganize
extents and directories, resize JFS file systems while online, and perform
an online backup using a snapshot of a JFS file system.
From the command line you can use:
• mkfs -F vxfs command to create a JFS file system (see mkfs_vxfs
(1M)).
• Any backup utility to perform a backup of a JFS file system except
fbackup (because it does not support read-only file systems) or dump.
• fsadm to view fragmentation, reorganize and resize JFS file systems.
(fsadm (1M) is available with HP OnLineJFS (also known as
Advanced VxFS.)
JFS and its Internal Operations
How does JFS work?