Veritas™ File System 5.0.1 Administrator's Guide

Table C-1
File system type and operating system versions (continued)
VxFS 5.0,
HP-UX 11i
v3
VxFS
5.0,
HP-UX
11.23 PI
VxFS
4.1,
HP-UX
11.23 PI
VxFS
3.5.2,
HP-UX
11.23 PI
VxFS
3.5,
HP-UX
11.11
JFS 3.3,
HP-UX
11.11
Disk Layout
YesYesYesNoNoNomkfs
Version
6
YesYesYesNoNoNo
Local
Mount
YesYesYesNoNoNo
Shared
Mount
YesYesYesNoNoNomkfs
Version
7
YesYesYesNoNoNo
Local
Mount
YesYesYesNoNoNo
Shared
Mount
VxFS Version 4 disk layout
The Version 4 disk layout allows the file system to scale easily to accommodate
large files and large file systems.
The original disk layouts divided up the file system space into allocation units.
The first AU started part way into the file system which caused potential alignment
problems depending on where the first AU started. Each allocation unit also had
its own summary, bitmaps, and data blocks. Because this AU structural information
was stored at the start of each AU, this also limited the maximum size of an extent
that could be allocated. By replacing the allocation unit model of previous versions,
the need for alignment of allocation units and the restriction on extent sizes was
removed.
The VxFS Version 4 disk layout divides the entire file system space into fixed size
allocation units. The first allocation unit starts at block zero and all allocation
units are a fixed length of 32K blocks. An exception may be the last AU, which
occupies whatever space remains at the end of the file system. Because the first
AU starts at block zero instead of part way through the file system as in previous
versions, there is no longer a need for explicit AU alignment or padding to be
added when creating a file system.
The Version 4 file system also moves away from the model of storing AU structural
data at the start of an AU and puts all structural information in files. So expanding
Disk layout
VxFS Version 4 disk layout
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