topic Re: Diffrerence between HFS ,VxFS and JFS in Operating System - HP-UX

Diffrerence between HFS ,VxFS and JFS

yogeshvar — Thu, 18 Jan 2007 00:40:53 GMT

Hi ALL,

Can any one tell me the difference between HFS ,VxFS and JFS/OnlineJFS ?
And what else File Systems is there for HP-UX?

I will be gratefull if you can provide me some doc's related to it?

Thanks in Advance,
Yogeshvar

Re: Diffrerence between HFS ,VxFS and JFS

Peter Godron — Thu, 18 Jan 2007 03:24:51 GMT

Hi,
lots of links:
docs.hp.com/en/B3929-90007/B3929-90007.pdf
http://en.wikipedia.org/wiki/VxFS
http://docs.hp.com/en/B2355-90672/ch04s04.html

Some of the points:

HFS (High Performance File System)
When you do not have any special file system needs.
Represents HP-UX's standard implementation of the UNIX File System (UFS).

VxFS (VERITAS File System)
Use if you require fast file system recovery and the ability to perform a variety of administrative tasks online.

Re: Diffrerence between HFS ,VxFS and JFS

Yogeeraj_1 — Thu, 18 Jan 2007 04:01:00 GMT

hi Yogeshwar,

see Table 2-4 HP-UX File System at: http://docs.hp.com/en/B2355-90950/ch02s05.html

JFS (Journaled File System)
When used:
Installed by default for HP-UX 11.0. Recommended for general purposes.
improves upon the High-Performance file system (HFS) in the following ways:
â ¢ faster recovery time versus HFS fsck, by using an intent log
â ¢ more robust than HFS, because JFS contains more panic avoidance code
â ¢ better performance under many circumstances, due to use of extents
â ¢ online administration, including backups, resizing, and defragmentation, using the optional HP OnLineJFS package

HFS (High Performance File System) - obsolete
When used:
When you need compatibility with earlier HP-UX releases.

VxFS (VERITAS File System)
For more information, please see: http://www.techsolutions.hp.com/en/5991-1833/5991-1833.pdf

there is also AdvFS (Advanced File System, which will be initially available in HP-UX 11i v3) file systems.

hope this helps too!
kind regards
yogeeraj

Re: Diffrerence between HFS ,VxFS and JFS

Sunny Jaisinghani — Thu, 18 Jan 2007 05:45:07 GMT

hi yogeshwar,

HP-UX supports many types of file systems. High Performance File System
(HFS) is used for the /stand mount point where the HP-UX kernel is stored.
Journaled File System (JFS) is used for other volumes in LVM. Network File
System (NFS) is used for mounting file systems over the network from a file
server. CD-ROM File System (CDFS) is used for storing files on CD-ROM.
Every file system has its own characteristics and methods of storing information.
From the user point of view, all file systems are the same, as the same
commands are used for file manipulation in all file systems.
One system can simultaneously have all supported types of file systems. You
can use the fstyp command to determine what type of file system is on a
particular device.

HFS:

HFS is the legacy file system used with HP-UX. Although JFS is used in the
newer versions of HP-UX, HFS is still in use for the /stand file system and is
supported on all HP-UX releases.
The first 8 Kbytes of all HFS file systems contain the HFS superblock, which
contains general information and pointers to the metadata area as already
discussed. HFS contains more than one copy of the superblock, and the
locations of these redundant copies are recorded in the /var/adm/sbtab file. If
the main superblock is damaged, it can be recovered from one of the backup
copies.

JFS:

JFS is the HP-UX version of the Veritas journaled File System (VxFS). This file
system exhibits fast recovery features. HP OnLineJFS (Advanced JFS) is an
extension to the base JFS and can be managed online (without unmounting). For
example, you can extend or shrink the file system without unmounting it.
Advanced JFS can also be defragmented and reorganized while it is in use. HP
OnlineJFS is not included with the standard HP-UX distribution and must be
purchased separately. A disadvantage of JFS is that the HP-UX kernel can't
reside on it.
Like HFS, JFS also maintains multiple copies of the superblock, but these are not
stored in any file. JFS keeps a record of these copies automatically. JFS keeps a
record of all transactions to the file system metadata area in an intent log. The
intent log is used for system recovery in case of a system crash. If a file system
update is completed successfully, a "done record" is written to the intent log
showing that this update request was successful. In case of a system crash, the
intent log is consulted and the file system brought to the stable state by removing
all unsuccessful transactions with the help of the intent log.
Another big advantage of JFS over HFS is that it creates inodes dynamically. So
if the inode table is full but there is still space on the file system, JFS can create
new inodes automatically.
Like HFS, JFS also divides the file system in JFS blocks. By default, the size of
each block is 1 KByte. JFS allocates a group of blocks when you create a new
file. This group of blocks is called an extent. If the file size grows, JFS tries to
allocate contiguous blocks to the file, thus increasing the size of the file extent.
However, if the contiguous blocks are not available, JFS creates a new extent
and allocates it to the file.

sunny