lvtab - information about logical volumes
The file /etc/lvtab describes the logical volumes used by the local
machine. There is an entry in this file for every logical volume which
is used by the system. This subsystem is no longer supported with the
current release. The file format description exists in order to
facilitate conversion to its replacement XLV.
The file consists of entries which have the form:
lv0:logical volume test:stripes=3:devs=/dev/dsk/ips0d1s7, \
Fields are separated by colons, and lines can be continued by the usual
backslash convention as illustrated above. A `#' as the first non-white
character indicates a comment; blank lines can be present in the file and
The fields in each entry have the following significance:
This indicates the names of the special files through which the
system accesses the logical volume. In the above example, the entry
lv0 implies that the logical volume is accessed via the device
special files /dev/dsk/lv0 and /dev/rdsk/lv0. Note that volume
device names are expected to be of the form 'lv' followed by one or
2 digits; this is enforced by the logical volume utilities.
This is a human-readable identifying name for the logical volume.
The logical volume labels on the disks constituting a volume also
carry a copy of the volume name, so utilities are able to check that
the logical volume on the disks physically present is actually the
volume expected by /etc/lvtab.
This field can be null (indicated by a second colon immediately
following the one terminating the volume_device_name field). This
is legal but deprecated, since in this case, no identity check of
the logical volume can be done by the utilities.
Some numerical options concerning the volume can appear. These are
specified in the format "option_name=number:". There must be no
space between the option_name, the '=' sign, the numerical value
given, and the terminating colon. Note that since the number of
options is variable, the terminating colon is considered part of the
option entry: it is not necessary to indicate omitted options.
Currently recognized options are:
The stripes option allows a striped logical volume to be created;
the value of the parameter specifies the number of ways the volume
storage is striped across its constituent devices. If this option
is omitted, the logical volume is unstriped.
The step option is meaningful only for striped volumes (and is
ignored otherwise); it specifies the granularity with which the
storage is to be round-robin distributed over the constituent
devices. If this option is omitted, the default step value is the
device tracksize; this is generally a good value so the step option
is not normally needed. step is in units of 512-byte blocks.
Following any numerical options, there must be a list of the block
special file pathnames of the devices constituting the logical
volume. This is introduced by the keyword
The pathnames must be comma-separated.
Each pathname should be the name of the special file for a disk
device partition in the /dev/dsk directory. The partition must be
one which is legal for use as normal data storage--it must not be
one of the dedicated partitions such as the disk volume label, track
replacement area, and so on.
If the volume is striped, some restrictions apply: the number of
pathnames must be a multiple of stripes. Further, considering the
pathnames as successive groups, each of stripes pathnames, the
devices in each group must be all of the same size.
To obtain best performance from striping, each disk (within every
group of stripes disks) should be on a separate controller.
The entries from this file are accessed using the program lv_to_xlv(1M),
which outputs a conversion script to translate between the two formats.
The file structure is defined in the <lvtab.h> include file.
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