topic Re: Regarding JFS in Operating System - HP-UX

Regarding JFS

Jasmin Berube — Wed, 14 Jun 2000 12:18:46 GMT

Is there any advantage to convert from HFS to VxFS to gain access time, because a monitor my server with glance and i notice disk bottleneck quite often? All my file systems are in HFS.

Re: Regarding JFS

Brian M. Fisher — Wed, 14 Jun 2000 12:26:44 GMT

As compared to HFS, JFS has these advantages:

-- Much shorter recovery times in the event of system failure

This is accomplished through the use of the intent log, which only
stores changes made to the file system structure, including partial
changes. When fsck is run on a JFS file system, by default, it
will only read the intent log, instead of the entire file system.
For more information, refer to the fsck_vxfs(1M) man page.

-- Much faster I/O

This is particularly useful in environments that require high
performance or deal with large volumes of data. This is
because the unit of file storage, called an extent, can be multiple
blocks, allowing considerably faster I/O than with HFS.

-- Much less downtime (if optional OnlineJFS is used)

The optional OnlineJFS product provides functionality not available
with HFS, such as online backups, online resizing, online
defragmentation, extent attributes, and caching advisories.
That is, unmounting the file system will not be necessary for
certain tasks.
This information is from Document#UNX1030190
http://us-support2.external.hp.com/cki/bin/doc.pl/

Brian
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Re: Regarding JFS

Michael Lampi — Mon, 19 Jun 2000 22:38:16 GMT

One thing you should be aware of is that there have been many, many, many patches issued for JFS (and LVM) that address issues such as data corruption.

Be sure you have the ones appropriate for your system.

Re: Regarding JFS

Dave Chamberlin — Tue, 20 Jun 2000 16:06:04 GMT

I also have some questions about this thread. I currently have several disks that
have Oracle Data on them that are all hfs and all have mirrors. How does the
mirroring affect changing from hfs to vxfs? Would changing to vxfs be a noticable
improvement in i/o?

Thanks

Re: Regarding JFS

Alan Riggs — Tue, 20 Jun 2000 18:11:22 GMT

Mirroring occurs at the logical volume leve. hfs vs vxfs has no impact upon Mirror-UX implementation. You will probably increase performance by shifting to vxfs filesystems. There is no way to "translate" from one form to another. You need to recreate the filesystem and restore data. This can be done manually or through a make_recovery/Ignite restoration.