Re: [Xen-users] snapshot - backup for xen vm's

[Ralf Schenk <rs@xxxxxxxxxx>]

Nico Kadel-Garcia schrieb:
> Ralf Schenk wrote:
>> it-news (Josef Lahmer) schrieb:
>>  
>>> dear list,
>>>
>>> is there a way to make a lvm-snapshot of an running xen-vm to
>>> implement a function like "snapshot-backup"?
>>>
>>>     
>> - Connect to mysql of VM and issue "FLUSH TABLES WITH READ LOCK;FLUSH
>> LOGS"
>>  
>>> #) make snapshot
>>>     
>> - Connect to mysql of VM and issue "UNLOCK tables"
>>  
>>> #) mount snapshot
>>> #) copy files
>>> #) umount snapshot
>>> #) remove snapshot
>>>
>>> eg (http://tldp.org/HOWTO/LVM-HOWTO/snapshots_backup.html)
>>>
>>> regards
>>> josy
>>>
>>> interessting: How to mount a XenVM filesystem on XenServer Host:
>>> http://kb.xensource.com/entry.jspa?categoryID=14&externalID=162
>>>     
>>
>> Hello !
>>
>> I do this every day. I added two points to your plan which I do with a
>> small perl script to get consistent Backups of my mysql Databases. I
>> also create/destroy the snapshot via this skript and mount the snapshot
>> volume. If you are interested I can send it via Mail.
>>   
> Could I talk you into publishing that tool on the list, please? Or
> sending me a copy to save me some work?
> 

Hello,

there is no secret except that I'm not a real programming guy in the few
lines....

Bye

-- 
__________________________________________________

Ralf Schenk
fon (02 41) 9 91 21-0
fax (02 41) 9 91 21-59
rs@xxxxxxxxxx

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Databay - einfach machen.

_________________________________________________

#!/usr/bin/perl
# Take perfect snapshot of mysql LVM by flushing mysql tables and
# setting a lock while creating the LVM snapshot
#
# usage: $0 (start|stop) [-v]
#
# Configurable
#
$dbi = "mysql";
$dbserver= "server.office.databay.de";
$dbport = "3306";
$dbname = "mysql";
$dbuser = "backup";
$passwd = "JzJe:64xUnrYKQus";

$mysql_vg = "/dev/server";
$mysql_lv = "/vm01";
$snapshot_name = "vm01_snap";
$snapshot_size = "5G";
$snapshot_mountpoint = "/mnt/vm01_snapshot";

#
# Normally you shouldn't change anything below this line
#
#---------------------------------------------------------------------------------------
use Time::Local;
#use POSIX qw(strftime);
use DBI;

my $start = (@ARGV && $ARGV[0] eq 'start');
my $stop = (@ARGV && $ARGV[0] eq 'stop');
my $verbose = (@ARGV && $ARGV[1] eq '-v' && shift);

if ($start) {
    #
    # Connect to database
    #
    my $connect = "DBI:".$dbi.":".$dbname.":".$dbserver.":".$dbport;
    my $dbh = DBI->connect($connect, 
        $dbuser, $passwd, 
        { RaiseError => 1}) 
        or die "connecting : $DBI::errstr\n";

    #
    # Flush tables and lock mysql for writing
    #
    my $start = time;
    my $sth = $dbh->do("FLUSH TABLES WITH READ LOCK;");
    my $sth = $dbh->do("FLUSH LOGS;");
    printf "Flushed and locked tables and logs in %d seconds.\n", time-$start 
unless !$verbose;

    #
    # Create LVM snapshot
    #
    my $start2 = time;
    printf "Executing /bin/sync;/sbin/lvcreate -s -L ".$snapshot_size." -n 
".$snapshot_name." ".$mysql_vg."/".$mysql_lv."\n" unless !$verbose;
    system("/bin/sync;/sbin/lvcreate -s  -L ".$snapshot_size." -n 
".$snapshot_name." -p r ".$mysql_vg."/".$mysql_lv);
    printf "Created LVM snapshot ".$snapshotname." in %d seconds.\n", 
time-$start2 unless !$verbose;
    #
    # Unlock tables
    #
    my $start3 = time;
    my $sth = $dbh->do("UNLOCK TABLES;");
    printf "Unlocked tables in %d seconds.\n", time-$start3 unless !$verbose;
    printf "Overall time for snapshot: %d seconds.\n", time-$start unless 
!$verbose;

    #
    # Disconnect from database
    #
    $dbh->disconnect;

    #
    # Mount snapshot
    #
    printf "Executing /bin/mount ".$mysql_vg."/".$snapshot_name." 
".$snapshot_mountpoint."\n" unless !$verbose;
    system ("/bin/mount ".$mysql_vg."/".$snapshot_name." 
".$snapshot_mountpoint);

} 

if ($stop) {
    printf "Executing /bin/umount ".$mysql_vg."/".$snapshot_name."\n" unless 
!$verbose;
    system ("/bin/umount ".$mysql_vg."/".$snapshot_name);
    printf "Executing /sbin/lvremove -f ".$mysql_vg."/".$snapshot_name."\n";
    system ("/sbin/lvremove -f ".$mysql_vg."/".$snapshot_name);
}

exit 0;

#
# Sub routines
#
sub fmtdate {
    my $string = shift;
    my ($DD, $MM, $YY, $hh, $mm, $ss) = ($string =~ m/(\d+).(\d+).(\d+) 
(\d+):(\d+):(\d+)/);
    return sprintf strftime("%y-%m-%d %H:%M:%S", $ss, $mm, $hh, $DD, $MM-1, 
$YY);
}    
sub now {
    my ($SEC, $MIN, $HOUR, $DAY, $MONTH, $YEAR) = (localtime)[0..5];
    return sprintf ("%04d-%02d-%02d %02d:%02d:%02d", $YEAR+1900, $MONTH+1, 
$DAY, $HOUR, $MIN, $SEC);
}

sub epoch {
    my $string = shift;
    my ($YYYY, $MM, $DD, $hh, $mm, $ss) = ($string =~ m/(\d+)-(\d+)-(\d+) 
(\d+):(\d+):(\d+)/);
    return timelocal($ss, $mm, $hh, $DD, $MM-1, $YYYY);
}

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