Re: [DRBD-user] BUG: Uncatchable DRBD out-of-sync issue

[Stanislav German-Evtushenko]

Just to make things clearer. These results are not false-positive, they are
real. False-positive also happen but rarely. I do check for false-positive
using the following script:
--
#!/bin/bash

# Usage: cat /var/log/kern.log | drbd_out_of_sync_compare.sh

#echo 'Mar 31 10:24:04 virt1 kernel: block drbd0: Out of sync:
start=1036171232, size=8 (sectors)'
while read line; do
if [[ $line =~ Out\ of\ sync:\ start=([0-9]+),\ size=([0-9]+) ]];
then
start=${BASH_REMATCH[1]}
size=${BASH_REMATCH[2]}
echo $start - $size
sum1=$(ssh 10.10.10.1 dd iflag=direct if=/dev/drbd0 bs=512
skip=$start count=$size 2>/dev/null < /dev/null | md5sum | awk '{print $1}')
sum2=$(ssh 10.10.10.2 dd iflag=direct if=/dev/drbd0 bs=512
skip=$start count=$size 2>/dev/null < /dev/null | md5sum | awk '{print $1}')
if [[ $sum1 = $sum2 ]]; then
echo OK: $sum1 - $sum2
else
echo ERR: $sum1 - $sum2
ssh 10.10.10.1 dd iflag=direct if=/dev/drbd0 bs=512
skip=$start count=$size 2>/dev/null < /dev/null > /tmp/${start}_${size}_1
ssh 10.10.10.2 dd iflag=direct if=/dev/drbd0 bs=512
skip=$start count=$size 2>/dev/null < /dev/null > /tmp/${start}_${size}_2
fi
fi
done
--

And results look like:
--
253182888 - 16
OK: 0829f71740aab1ab98b33eae21dee122 - 0829f71740aab1ab98b33eae21dee122
253182904 - 8
OK: 620f0b67a91f7f74151bc5be745b7110 - 620f0b67a91f7f74151bc5be745b7110
253182952 - 8
OK: 620f0b67a91f7f74151bc5be745b7110 - 620f0b67a91f7f74151bc5be745b7110
253250344 - 8
OK: 620f0b67a91f7f74151bc5be745b7110 - 620f0b67a91f7f74151bc5be745b7110
253259336 - 8
OK: 620f0b67a91f7f74151bc5be745b7110 - 620f0b67a91f7f74151bc5be745b7110
719214256 - 8
OK: 0132ffdc961a93ab39f3687b2168b326 - 0132ffdc961a93ab39f3687b2168b326
719214264 - 8
OK: e824f6f1a60c23fea04cfb5d080747c2 - e824f6f1a60c23fea04cfb5d080747c2
719299576 - 8
OK: a969c6562450baa0c5306fe89fe6d4f9 - a969c6562450baa0c5306fe89fe6d4f9
1085832880 - 8
OK: 9da8849288dcaa863b96d6cf5d9fee09 - 9da8849288dcaa863b96d6cf5d9fee09
1085972048 - 8
ERR: 708d5019b36d8bc6ef68fbdf431efbb3 - bffe661e808e1b42a4c5e1cad490ec0c
1085972072 - 8
ERR: a381fea0de0a34d01db0e4d7a9f9e824 - d1d6d30932ba15611cfac831e337e634
1086079632 - 8
ERR: 75e2d49f51a691998d1e9023b252aa51 - d367cfbd482fde9827ccef063b4b55a9
1086079528 - 8
ERR: 08637fb9b63c59db91c8179a22c9e4f7 - e421dc61e71d95bc63d9ab3fd834aa3e
1086079592 - 8
ERR: 483c379d346769f711721b4df154415b - 132f45d198b603e3f33cee750a21602d
1086079440 - 16
ERR: a8cb7da5e9da13d910b5afdbdb2721d9 - 717acb3d5b7403690f4f33340855a14c
1086128384 - 8
ERR: 31a1740dce4b305eb7a888a35de48ac8 - 53bc81a20e9ab5bddba35d742d3a7551
--

Most of the time (99%) I see ERR for the swap space of virtual machines.

Best regards,
Stanislav
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Re: [DRBD-user] formatting a DRBD resource

[Digimer]

On 29/01/14 06:40 PM, Paul O'Rorke wrote:

Hi all,

a quick question.  I have a DRBD resource that was once used as a drive
for a Linux machine that used LVM.  I want to create a new VM (KVM
based) that uses this resource.  I can start the installation OK - the
installer 'sees' the 300GB drive (/dev/drbd/by-res/) but when
I try using the partition manager in the Debian (guest) installer it
complains that there is already LVM data on there and it won't allow me
to use the drive without first cleaning up the LVM config on there.

Is it possible to mount the resource in the host and use the command
line LVM tools to 'clean' that up?  I was thinking that maybe I could
use *dd* to clone a new clean resource of the same size but that seems
silly.

Does anyone have any suggestions for 'formatting' this resource so that
it looks again like a clean un-partitioned disk?

Thanks in advance.


Simplest would be to write zeros to the device;

dd if=/dev/zero of=/dev/drbd/by-res/ bs=4M

If you know that the LVM metadata is at the first or end of the drive, 
you can limit the dd to count=X or use of offset to hit the end of the 
resource.


--
Digimer
Papers and Projects: https://alteeve.ca/w/
What if the cure for cancer is trapped in the mind of a person without 
access to education?

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[DRBD-user] formatting a DRBD resource

[Paul O'Rorke]

Hi all,

a quick question.  I have a DRBD resource that was once used as a drive 
for a Linux machine that used LVM.  I want to create a new VM (KVM 
based) that uses this resource.  I can start the installation OK - the 
installer 'sees' the 300GB drive (/dev/drbd/by-res/) but when 
I try using the partition manager in the Debian (guest) installer it 
complains that there is already LVM data on there and it won't allow me 
to use the drive without first cleaning up the LVM config on there.


Is it possible to mount the resource in the host and use the command 
line LVM tools to 'clean' that up?  I was thinking that maybe I could 
use *dd* to clone a new clean resource of the same size but that seems 
silly.


Does anyone have any suggestions for 'formatting' this resource so that 
it looks again like a clean un-partitioned disk?


Thanks in advance.
--

*Paul O'Rorke*
Tracker Software Products
p...@tracker-software.com 

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