mdw@git.distorted.org.uk Git - distorted-backup/blob - snap.lvm

   1 #! /bin/sh
   2 ###
   3 ### Establish snapshots of LVM logical volumes
   4 ###
   5 ### (c) 2011 Mark Wooding
   6 ###
   7
   8 ###----- Licensing notice ---------------------------------------------------
   9 ###
  10 ### This program is free software; you can redistribute it and/or modify
  11 ### it under the terms of the GNU General Public License as published by
  12 ### the Free Software Foundation; either version 2 of the License, or
  13 ### (at your option) any later version.
  14 ###
  15 ### This program is distributed in the hope that it will be useful,
  16 ### but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ### GNU General Public License for more details.
  19 ###
  20 ### You should have received a copy of the GNU General Public License
  21 ### along with this program; if not, write to the Free Software Foundation,
  22 ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  23
  24 set -e
  25 quis=${0##*/}
  26
  27 ###--------------------------------------------------------------------------
  28 ### Parse the command line.
  29
  30 ## Provide help or version information.
  31 usage="usage: $quis DEVICE [KEY=VALUE ...]"
  32 version="$quis, version 1.0.0"
  33 case "$#,$1" in
  34   0,*) echo >&2 "$usage"; exit 1 ;;
  35   *,-v | *,--version) echo "$version"; exit ;;
  36   *,-h | *,--help)
  37     cat <<EOF
  38 $version
  39 $usage
  40
  41 Option keys:
  42   op=OPERATION          \`snap' to create snapshot, or \`unsnap' to remove.
  43   snapsz=SIZE           Size to reserve for snapshot storage.
  44   tag=TAG               Disambiguation tag to append to logical volume name.
  45 EOF
  46     exit
  47     ;;
  48 esac
  49
  50 ## Scan the option keys.
  51 dev=$1; shift
  52 Oop=snap Otag=snap Osnapsz=100M
  53 win=t
  54 for i in "$@"; do
  55   case "$i" in
  56     ?*=*) ;;
  57     *) echo >&2 "$quis: malformed option \`$i'"; exit 1 ;;
  58   esac
  59   k=${i%%=*} v=${i#*=}
  60   case "$k" in *.lvm) k=${k%.lvm} ;; ?*.?*) continue ;; esac
  61   case "$k" in
  62     op | tag | snapsz) eval "O$k=\$v" ;;
  63     *) echo >&2 "$quis: unknown option \`$k'"; win=nil ;;
  64   esac
  65 done
  66 case $win in nil) exit 1 ;; esac
  67
  68 ## Check the device name.
  69 case "$dev" in
  70   ?*/?*) ;; *) echo >&2 "$quis: device \`$dev' should be VG/LV"; exit 1 ;;
  71 esac
  72 vg=${dev%%/*} lv=${dev#*/}
  73
  74 ###--------------------------------------------------------------------------
  75 ### Take or remove the snapshot.
  76
  77 case "$Oop" in
  78
  79   snap)
  80     case "$Osnapsz" in
  81       *%*) szarg="extents" ;;
  82       *) szarg="size" ;;
  83     esac
  84     lvcreate >/dev/null --snapshot \
  85       --$szarg="$Osnapsz" \
  86       --name="$lv.$Otag" \
  87       "$vg/$lv"
  88     echo "$vg/$lv.$Otag"
  89     ;;
  90
  91   unsnap)
  92     ## LVM snapshot removal is full of awful bugs, mostly to do with races
  93     ## with udev.  We have a handy script which does the necessary.  May it
  94     ## not be needed for long.
  95     lvm-rmsnap >/dev/null "$vg/$lv.$Otag"
  96     ;;
  97
  98   *)
  99     echo >&2 "$quis: unknown operation \`$Oop'"
 100     exit 1
 101     ;;
 102
 103 esac
 104
 105 ###----- That's all, folks --------------------------------------------------