[DRBD-user] CHS versus LBA

[Lars Ellenberg]

/ 2006-02-19 00:07:34 +0000
\ Casey Allen Shobe:

[ Node1, LBA ]
> /dev/hda3             520        1245     5831595   83  Linux
[ Node2, C/H/S ]
> /dev/hda3            8249       19857     5850936   83  Linux

> hda3 is what drbd0 uses.  As you can see the block size is different for each.  
> It contains a reiserfs partition and doesn't seem to be causing any 
> problems...yet...but it concerns me.
> I don't have any recollection of which machine the filesystem was mkfs'd on.

now. as long as you mkfs'd on /dev/drbdX, as is recommended,
and drbd has been connected while you mkfs'd, all is well.

if not:
below perl scriptlet should help in "guessing" the size occupied by reiserfs
and the size of the device.

save as "get_size_of_reiserfs.pl",
and use like "perl get_size_of_reiserfs.pl /dev/drbd0" on the primary node.

[ remember, if you use drbd "meta-data internal", the /dev/drbdX
  is 128MB smaller than the lower level device (/dev/hda3)!      ]
if it seems to be larger than the available space on the drbd,
you should shrink the fs as long as you still can.

-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-
#!/usr/bin/perl

@ARGV == 1 or die "usage: $0 device\n";

$device = $ARGV[0];
-b $device or die "$device is not a block device\n";

open B, "<", $device or die "open $device: $!\n";
sysread(B,$data,0x11000) == 0x11000 or die "sysread: $!\n";
if ( "ReIsErFs"  eq substr($data,0x10034,8) or
     "ReIsEr2Fs" eq substr($data,0x10034,9) )
{
        $bnum  = unpack "V",substr($data,0x10000,4);
        $bsize = unpack "v",substr($data,0x1002c,2);
        $size = $bnum * $bsize;
        $bd_size = `blockdev --getsize64 $device`;
        print "$device:\n";
        print "blockdev --getsize64 reports a size of               $size Bytes\n";
        print "seems to contain a reiserfs of ($bnum \@ $bsize) == $size Bytes\n";
        $size /= 1024;
        print "                                                  == $size KBytes\n";
} else {
        die "$device does not look like a reiserfs to me... :(";
}
-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-8<-=-

-- 
: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
: Schoenbrunner Str. 244, A-1120 Vienna/Europe   http://www.linbit.com :
__
please use the "List-Reply" function of your email client.