Mknod Post: 302199765

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Operating Systems HP-UX Mknod Post 302199765 by Perderabo on Tuesday 27th of May 2008 09:54:09 PM

05-27-2008

Administrator Emeritus

mknod is a utility to make filesystem objects. In the case of LVM you might do:
mknod /dev/vgxyz/group c 64 0x030000

You can call a volume group vgxyz if you want, but you must have a file called "group" in it. This form of mknod is making a character special file. 64 is the number of the LVM driver. (lsdev can list drivers.) 0x030000 is a unique number that you must pick to identify the volume group to the kernel. To you it's the vgxyz volume group, but to the kernel, it's the 03 volume group. The group file connects /dev/xyz to the number 03. Anytime you do a vgchange or whatever, the vgchange command needs to let the kernel know what's happening and it talks to the group file to do that.

Cameron, you should be using mkfifo to make your fifo's. And fifo's (aka named pipes) have nothing to do with this.

Perderabo

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LEARN ABOUT REDHAT

vgreduce

VGREDUCE(8)						      System Manager's Manual						       VGREDUCE(8)

NAME

       vgreduce - reduce a volume group

SYNOPSIS

       vgreduce [-a|--all] [-A|--autobackup{y|n}] [-d|--debug] [-h|--help] [-v|--verbose] VolumeGroupName [PhysicalVolumePath...]

DESCRIPTION

       vgreduce allows you to remove one or more unused physical volumes from a volume group.

   OPTIONS
       -a, --all
	      Removes all empty physical volumes if none are given on command line.

       -A, --autobackup y/n
	      Controls automatic backup of VG metadata after the change ( see vgcfgbackup(8) ). Default is yes.

       -d, --debug
	      Enables additional debugging output (if compiled with DEBUG).

       -h, --help
	      Print a usage message on standard output and exit successfully.

       -v, --verbose
	      Gives verbose runtime information about vgreduce's activities.

DIAGNOSTICS

       vgreduce returns an exit code of 0 for success and > 0 for error:

       1  neither volume group name nor physical volume path(s) on command line
       2  invalid volume group name
       3  error checking existence of volume group
       4  volume group must be active
       5  error reading VGDA
       6  volume group is not reducable (see vgchange(8))
       7  no physical volume path(s) on command line
       8  realloc error
       9  malloc error
       10 no empty physical volume to reduce volume group by
       11 error setting up VGDA for reduce
       12 error reducing VGDA in kernel
       13 error writing VGDA to physical volume(s)

       95 driver/module not in kernel
       96 invalid I/O protocol version
       97 error locking logical volume manager
       98 invalid lvmtab (run vgscan(8))
       99 invalid command line

ENVIRONMENT VARIABLES

       LVM_AUTOBACKUP
	      If this variable is set to "no" then the automatic backup of VG metadata is turned off.

       LVM_VG_MAX_BACKUPS
	      This  variable  determines  the  backup  history	depth  of kept VGDA copy files in /etc/lvmconf. It can be set to a positive number
	      between 0 and 999.  The higher this number is, the more changes you can restore using vgcfgrestore(8).

See also
       lvm(8), vgextend(8)

AUTHOR

       Heinz Mauelshagen <Linux-LVM@Sistina.com>

Heinz Mauelshagen						     LVM TOOLS							       VGREDUCE(8)