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

Dusty Mabe dustymabe at yahoo.com
Fri Oct 14 13:07:57 UTC 2011


Ray, 

Thanks so much for your answer. You said the feature is being "worked on". I see some work related to thin provisioning "pools" in the latest LVM code. Is this the work you are referring to? If so do you know anything about it (maybe just a paragraph about how it works)? This has peaked my interest and I look forward to what LVM has to offer in the future.

Have a good day!

Dusty 


----- Original Message -----
From: Ray Morris <support at bettercgi.com>
To: linux-lvm at redhat.com
Cc: Dusty Mabe <dustymabe at yahoo.com>
Sent: Thursday, October 13, 2011 2:25 PM
Subject: Re: [linux-lvm] dynamic lvm snapshots (auto-resize)

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
support at bettercgi.com

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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
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
> 


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