[linux-lvm] dynamic lvm snapshots (auto-resize)

[Ray Morris]

I think that's being worked on / beta. Until it's ready, we implemented
it in a daemon that is 49 lines of Perl. This particular implementation 
is set to match our environment but you can modify it to your needs:

#!/usr/bin/perl

use Getopt::Long;
use lib 'lib';
use Linux::LVM;

my $lvname;
my $usage = "usage: $0 --lvname lvname\n";
die $usage unless ( GetOptions ( "lvname=s" => \$lvname ) );
die $usage unless ($lvname);

my $ppid = getppid();
while ( -e "/proc/$ppid") {
  &check_snaps($lvname);
  sleep(60);
}

sub check_snaps {
  my $lvname = shift();
  for ($snapnum = 2; $snapnum >= 0; $snapnum--) {
    if (-e "/dev/clones/${lvname}_snap${snapnum}") {
      my %lv = get_lv_info("/dev/clones/${lvname}_snap${snapnum}");
      next unless ($lv{'lv_name'});
      unless ($lv{'allocated_to_snapshot'}) {
          system('lvremove', '-f', "clones/${lvname}_snap${snapnum}");
          next;
      }
      if ($lv{'allocated_to_snapshot'} > 80) {
          print "live extending ${lvname}_snap${snapnum}\n";
          system('lvextend', '-f', '-l', '+20%LV', "clones/${lvname}_snap${snapnum}");
      }
    }
  }
}
-- 
Ray Morris
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On Thu, 13 Oct 2011 10:28:56 -0700 (PDT)
Dusty Mabe <dustymabe at yahoo.com> wrote:

> Hi Everyone,
> 
> I am interested to see if there is any support for automatically
> resizing an lvm snapshot when it becomes full or bypasses a certain
> utilization? There has been  at least some interest in this in the
> past as I have found the following post in the mailman archives. 
> 
> http://www.redhat.com/archives/linux-lvm/2007-November/msg00016.html
> 
> 
> Also it looks like HP as performed at least a similar implementation
> of this type of feature in their own product. 
> 
> http://bizsupport1.austin.hp.com/bc/docs/support/SupportManual/c02054539/c02054539.pdf
> 
> 
> 
> Thanks for any Help!!
> 
> Dusty Mabe
> 
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>