JFS

If you choose to do that, consider turning off JFS logging on your new file system before you start copying to it.

JFS is required for SMS on AIX, and no concurrent access is possible in this case.

The next step in the evolution of this model is wrapping one toolkit (like Dojo) with another like (JSF).

Before we get to JFS and EVMS, let me share an official update about the current state of affairs in the Linux filesystem world.

JFS is a key technology for Internet file servers since it provides fast file system restart times in the event of a system crash.

The JFS architecture can be explained in the context of its disk layout characteristics.

JFS, from IBM: showing its age now, but a good performer in its day on small drives and files.

JFS logs are maintained in each aggregate and used to record information about operations on meta-data.

It doesn't take much to make a superblock dirty, cause fragmentation, mess up inodes, or cause repeating JFS errors in the errpt.

JFS provides standard administration utilities for creating and maintaining file system.

Having a different logical name for each disk (if raw devices) or file system (if SMS, and thus JFS) has its advantages and disadvantages.

JFS will report the size of this file as 100 blocks, although only 1 block of disk space has been allocated to it.

With ReiserFS, XFS, and JFS, the filesystem driver journals metadata, but makes no provisions for journaling data.

JFS provides fast file system restart in the event of a system crash.

Consider just our options for a journaling filesystem: ReiserFS, ext3, XFS, and JFS.

There are no persistent storage pages (because there are no JFS filesystems in use on the system).

XFS and JFS, unfortunately, cannot be shrunk, although they can be grown or moved.

For jfs, you can use splitcopy or, for jfs2, use snapshot to take a copy of a filesystem.

Don't worry, this series will will be wrapping up soon as I cover IBM's JFS and EVMS (enterprise volume management) technologies for Linux.

Create the JFS log before creating the logical volumes for the volume groups.

Non-client pages are pages containing cached Journaled File System (JFS) file data.

Repeat this process to create another LV of type jfs and named hblv (but otherwise identical).

Remember also that, although you can shrink most Linux-native file systems, you can't shrink XFS or JFS.

Table 2 details specific tuning parameters that you use often for JFS file systems.

JFS commits atime updates asynchronously.

JFS logging style has been improved over time and now provides asynchronous logging, which increases performance of the file system.

A number of features in JFS distinguish it from other file systems.

JFS supports both sparse and dense files, on a per-file system basis.

We used system managed space (SMS) and journaled file system (JFS).

Note: In AIX you can only use JFS for SMS tablespaces.

Next, you need to determine which line is causing the problem in jfs_mount.

There are two types of file system structures in AIX: journaled file systems (JFS) and enhanced journaled file systems (JFS2).

This allows JFS to support both large files and partitions.

The current version of JFS on flash is JFFS2 (described later in this article).

JFS and JFS2 file systems require a logical volume for the JFS log.

JFS was first released in 1990, but the current version supported in Linux is the later-developed JFS2.

For example, Journaled File System (JFS) can be built as a module or directly into the kernel.

Then there are the folks who insist that ext3 is not a true journaling filesystem, but JFS, and so on.

If you are working with JFS, Reiser, or other file systems, you will need to use a different utility, such as tar.

The quota support for JFS2 and JFS can be used on the same system.

You should then mount the file system on the target LPAR using the normal JFS logging (without using the NOLOG option).

Create the logical volumes and the JFS sytems.

JFS2 has been optimized for the 64-bit kernel, while JFS is optimized for the 32-bit kernel.

One way you can do this is to use the objdump utility on the jfs_mount. o file and look at offset 3c.

IBM introduced JFS with the initial release of AIX 3. 1. In May of 2001, IBM introduced JFS2.

File deletion effects were similar, ranging from 1. 04 (for XFS) to 4. 78 (for JFS), with a mean of 1. 97.

These values ranged from 1. 10 (for XFS and JFS) to 6. 02 (for ReiserFS), with a mean of 2. 10.

It can be used on ext2, ext3, jfs, Reiser, and other file systems.