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Dual primary mounted partitions not showing changes

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Danny at eonar

Nov 4, 2009, 5:27 AM

Post #1 of 5 (302 views)
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Dual primary mounted partitions not showing changes

I've been working at creating a highly available set of host servers for a
linux diskless boot cluster. Each host machine is fitted with redundant
power supplies and two 1TB drives in a Raid-1 configuration.

When I first started this project they each had twin 160GB drives. In my
original setup I had both nodes acting as primary systems so that I could
mount /dev/drbd0 to my /data directory and see changes immediately. It had
worked in the past where I could make a file in /data on the first machine
and it would show up in the /data directory on the second machine. One day
this had stopped working where if I made a file on the first machine it
would display on the second one until I unmounted /data and remounted it to
the /dev/drbd0 disk. This is when I bought the new disks and decided to
start from scratch.

Below is my configuration file, sda8 is an 820GB partition which is used for
all of the data I want to replicate, currently populated with ~10GB of data.
Sda7 is my metadisk partition which is 500MB large clearly more than needed
by drbd.

Also you will notice "incon-degr-cmd "halt -f";" is commented out. This is
because when I go to actually use it drbd throws an error when reloading the
configuration and I'm not sure why that is either.

resource r0 {
protocol C;
#incon-degr-cmd "halt -f";
net {
allow-two-primaries;
after-sb-0pri discard-zero-changes;
after-sb-1pri discard-secondary;
after-sb-2pri disconnect;
}
startup {
become-primary-on both;
}
disk {
on-io-error detach;
}
syncer {
rate 128M; # Note: 'M' is MegaBytes, not MegaBits
}
on dh1.domain.com {
device /dev/drbd0;
disk /dev/sda8;
address 192.168.1.140:7789;
meta-disk /dev/sda7[0];
}
on dh2.domain.com {
device /dev/drbd0;
disk /dev/sda8;
address 192.168.1.141:7789;
meta-disk /dev/sda7[0];
}
}
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iustin at google

Nov 4, 2009, 9:24 AM

Post #2 of 5 (280 views)
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Re: Dual primary mounted partitions not showing changes [In reply to]

On Wed, Nov 04, 2009 at 05:27:28AM -0800, dascione wrote:
> When I first started this project they each had twin 160GB drives. In my
> original setup I had both nodes acting as primary systems so that I could
> mount /dev/drbd0 to my /data directory and see changes immediately. It had
> worked in the past where I could make a file in /data on the first machine
> and it would show up in the /data directory on the second machine. One day
> this had stopped working where if I made a file on the first machine it
> would display on the second one until I unmounted /data and remounted it to
> the /dev/drbd0 disk.

What filesystem are you using?

regards,
iustin
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linux at alteeve

Nov 4, 2009, 10:44 AM

Post #3 of 5 (274 views)
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Re: Dual primary mounted partitions not showing changes [In reply to]

Iustin Pop wrote:
> On Wed, Nov 04, 2009 at 05:27:28AM -0800, dascione wrote:
>> When I first started this project they each had twin 160GB drives. In my
>> original setup I had both nodes acting as primary systems so that I could
>> mount /dev/drbd0 to my /data directory and see changes immediately. It had
>> worked in the past where I could make a file in /data on the first machine
>> and it would show up in the /data directory on the second machine. One day
>> this had stopped working where if I made a file on the first machine it
>> would display on the second one until I unmounted /data and remounted it to
>> the /dev/drbd0 disk.
>
> What filesystem are you using?
>
> regards,
> iustin

Also, what does 'cat /proc/drbd' show on either node?

I think iustin is asking for a similar reason that I was going to ask;
Is the filesystem cluster-aware and properly implementing locking?

Madi
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Danny at eonar

Nov 4, 2009, 10:56 AM

Post #4 of 5 (264 views)
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Re: Dual primary mounted partitions not showing changes [In reply to]

Iustin Pop-2 wrote:
>
> What filesystem are you using?
>
> regards,
> iustin
>

I WAS using the ext3 filesystem. After posting this I started looking for
sync problems with ext3 and ext2 filesystems even though I wasn't using
ext2. One topic came up and the guy had the same exact problem. Anyway the
result of the post was that ext3 is not a shared filesystem and he had to
use one of a specific list of shared filesystems in order for it to work.
It makes sense that it will not work with ext3.

A list of shared filesystems and block devices were listed:

Shared Block Devices:
SAN
Dual attached SCSI
GNBD
DRBD
iSCSI

Shared Filesystem:
gfs
gfs2
gpfs
ocfs
ocfs2

I choose to go with the ocfs2 filesystem and found a complete guide to
setting it up with my current configuration of DRBD without having to
invalidate all my data on the second machine and resync. Here is a link to
the guide http://www.drbd.org/users-guide/ch-ocfs2.html

Just for the record my problem is solved, thank you guys. For anyone else
that comes across this I hope the information above suffices for a
resolution for your problem.

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martin at isg

Nov 5, 2009, 1:51 AM

Post #5 of 5 (266 views)
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Re: Dual primary mounted partitions not showing changes [In reply to]

Be careful, by default, creating a new filesystem is destructive operation.

Regards,
M.

dascione wrote:
>
> Iustin Pop-2 wrote:
>> What filesystem are you using?
>>
>> regards,
>> iustin
>>
>
> I WAS using the ext3 filesystem. After posting this I started looking for
> sync problems with ext3 and ext2 filesystems even though I wasn't using
> ext2. One topic came up and the guy had the same exact problem. Anyway the
> result of the post was that ext3 is not a shared filesystem and he had to
> use one of a specific list of shared filesystems in order for it to work.
> It makes sense that it will not work with ext3.
>
> A list of shared filesystems and block devices were listed:
>
> Shared Block Devices:
> SAN
> Dual attached SCSI
> GNBD
> DRBD
> iSCSI
>
> Shared Filesystem:
> gfs
> gfs2
> gpfs
> ocfs
> ocfs2
>
> I choose to go with the ocfs2 filesystem and found a complete guide to
> setting it up with my current configuration of DRBD without having to
> invalidate all my data on the second machine and resync. Here is a link to
> the guide http://www.drbd.org/users-guide/ch-ocfs2.html
>
> Just for the record my problem is solved, thank you guys. For anyone else
> that comes across this I hope the information above suffices for a
> resolution for your problem.
>
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