lvtab(4)							      lvtab(4)

NAME    [Toc]    [Back]

     lvtab - information about logical volumes

DESCRIPTION    [Toc]    [Back]

     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:

	  volume_device_name:[volume_name]:[options:]device_pathnames

     For example:

	  lv0:logical volume test:stripes=3:devs=/dev/dsk/ips0d1s7, \
	  /dev/dsk/ips0d2s7, /dev/dsk/ips0d3s7

     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
     are ignored.

     The fields	in each	entry have the following significance:

     volume_device_name
	  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.

     volume name
	  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.

     options
	  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



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lvtab(4)							      lvtab(4)



	  option entry:	it is not necessary to indicate	omitted	options.

	  Currently recognized options are:

	       stripes=
	       step=

	  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.

     device_pathnames
	  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

	       devs=

	  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.

FILES    [Toc]    [Back]

     /etc/lvtab







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lvtab(4)							      lvtab(4)



SEE ALSO
     lv_to_xlv(1M),


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