Re: [DRBD-user] DRBD9: full-mesh and managed resources

[dan]

On Thu, Aug 18, 2016 at 6:03 AM, Veit Wahlich  wrote:
> But the shortest link is not guaranteed. Especially after recovery from
> a network link failure.
> You might want to monitor each node for the shortest path.

Simplest solution here is to overbuild.  If you are going to do a
3-node 'full-mesh' then you should consider 10G ethernet (a melanox w/
cables on ebay is about US$20 w/ cables!).  Then you just enable STP
on all the bridges and let it be.  If you are taking 2 hops, that
should still be well over the transfer rates you need for such a small
cluster and STP will eventually work itself out.
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Re: [DRBD-user] DRBD9: full-mesh and managed resources

[Veit Wahlich]

Am Donnerstag, den 18.08.2016, 12:33 +0200 schrieb Roberto Resoli:
> Il 18/08/2016 10:09, Adam Goryachev ha scritto:
> > I can't comment on the DRBD related portions, but can't you add both
> > interfaces on each machine to a single bridge, and then configure the IP
> > address on the bridge. Hence each machine will only have one IP address,
> > and the other machines will use their dedicated network to connect to
> > it. I would assume the overhead of the bridge inside the kernel would be
> > minimal, but possibly not, so it might be a good idea to test it out.
> 
> Very clever suggestion!
> 
> Many thanks, will try and report.

If you try this, take care to enable STP on the bridges, or this will
create loops.
Also STP will give you redundancy in case a link breaks and will try to
determine the shortest path between nodes.

But the shortest link is not guaranteed. Especially after recovery from
a network link failure.
You might want to monitor each node for the shortest path.

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[DRBD-user] Ressource decomission stuck

[Julien Escario]

Hello,
After rebooting a node, I can see somthing strange :

# drbdmanage list-assignments
> | vm4  | vm-206-disk-1 |  * | |   
> ok |
> | vm5  | vm-206-disk-1 |  * | |   
> ok |
> | vm7  | vm-206-disk-1 |  * | | 
> FAILED(3), pending actions: decommission |

So it seems the ressource removal is stuck in the middle of the operation.

I already tried different actions so I can't assume it was in this state before.

I'm using lvm thin as plugin and I don't have any more vm-206-disk-1 lv and
drdbadm status returns nothing about this ressource.

Is there a way to remove this properly ? I guess I would be able to reassign the
ressource to this node after.

And moving /var/lib/drbd.d/drbdmanage_vm-206-disk-1.res away didn't change 
anything.

Best regards,
Julien



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Re: [DRBD-user] DRBD9: full-mesh and managed resources

[Roberto Resoli]

Il 18/08/2016 10:09, Adam Goryachev ha scritto:
>>
> I can't comment on the DRBD related portions, but can't you add both
> interfaces on each machine to a single bridge, and then configure the IP
> address on the bridge. Hence each machine will only have one IP address,
> and the other machines will use their dedicated network to connect to
> it. I would assume the overhead of the bridge inside the kernel would be
> minimal, but possibly not, so it might be a good idea to test it out.

Very clever suggestion!

Many thanks, will try and report.

rob


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Re: [DRBD-user] DRBD9: full-mesh and managed resources

[Roland Kammerer]

On Thu, Aug 18, 2016 at 09:47:51AM +0200, Roberto Resoli wrote:
> In particular I see that currently is not possible to dedicate an IP for
> every different link betwen a managed resource and its peer node.
> 
> Am I wrong?

No.

> Any advice/suggestion?

Don't do it ;-).

We had that discussion on the ML. If you manually overwrite res files
generated by DRBD Manage, they can get rewritten by DRBD Manage at "any
time".

Currently, it is simply not supported from a DRBD Manage point of view.
To be honest, it is not on my TODO list.

Regards, rck
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Re: [DRBD-user] Is DRBD9 ready for production

[Julien Escario]

Le 11/08/2016 09:10, Ml Ml a écrit :
> Hello List,
> 
> i wonder if DRBD9 is ready for production?
> 
> I posted my Problem here:
>   http://lists.linbit.com/pipermail/drbd-user/2016-April/022893.html
> 
> And i ran into this problem a few times now. So i switched to a 2 Node
> Setup (which works fine so far).
> 
> Everytime i go back to a 3 Node Cluster it takes only a few days and i
> run into the "ASSERTION FAILED: pp_in_use" problem again.
> 
> Please tell me if this is "just" a bug (bugs can happen) or if i
> should NOT use DRBD9 for production environment.

Just to give a little feedback : we're running a 3 proxmox nodes cluster with
DRBD9 and drbdmanage and everything works as expected.

Of course, it didn't went up out of the box and a test cluster was useful in
order to test drive everything together, know were the caveats are and what
could be done or not.

I've almost completed upgrade of our cluster with the latest proxmox version by
migrating one by one all VMs, upgrading, rebooting, etc ...

This should be done in a specific order and I had to read a lot of 
documentation.

Just to complete : we had a switch outage and our 3 nodes were full disconnected
at once a few weeks ago : nothing special happened, once the switch came back a
few minutes after, all ressources resync and we didn't had a crash and
split-brain, etc ...

The last strange behavior I had is that after rebooting nodes, a few ressources
were in state StandAlone. As it's a production cluster, I didn't try to resolve
this the proper way and ask for unassign/re-assign. This asked a full resync and
a little time but after, all ressources went back to normal.

So MY answer is : DRBD9 is production ready but be prepared to run a test
cluster and make some crash tests before going into production. Test cluster
MUST remain active to try any upgrade procedure before applying to production.

My 2cts,
Julien



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Re: [DRBD-user] drbdmanage v0.97

[Julien Escario]

Le 17/08/2016 12:19, Roland Kammerer a écrit :
> On Wed, Aug 17, 2016 at 11:34:22AM +0200, Julien Escario wrote:
>> So my question now : is there a way to restart drbdmanage 'server' without
>> having to restart the whole server ? As it's dbus, I don't want to create a
>> mess.
> 
> "drbdmanage restart -q"

Great ! It seems to be a new command, I can't see it on previous drbdmanage
version (at least with 0.91).

It works like a charm, no ressource where disconnect on my 2 nodes cluster,
everything continued to works as expected.

And right after, I created a 100GB disk which went UpToDate instantly and
consuming around 0 disk space ON BOTH NODES.

This is really a great feature, many thanks !

Best regards,
Julien




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[DRBD-user] Replication Problems

[Raman Gupta]

Hi,

I am using DRBD version 8.4 on CentOS6 and having some issues in
understanding the replication mechanism.

Configuration Details:
-
[root@centos6 ~]# drbdadm --version
DRBDADM_API_VERSION=1
DRBD_KERNEL_VERSION_CODE=0x080407
DRBDADM_VERSION_CODE=0x080905
DRBDADM_VERSION=8.9.5

[root@centos6 ~]# rpm -qa | grep drbd
drbd84-utils-8.9.5-1.el6.elrepo.x86_64
kmod-drbd84-8.4.7-1_1.el6.elrepo.x86_64


DRBD Configuration on both Primary and Secondary nodes:
-
resource r0
{
on centos6
{
device/dev/drbd1;
disk/dev/sdb;
address10.168.150.2:7789;
meta-diskinternal;
}

on vm-centos6-dev1
{
device/dev/drbd1;
disk/dev/vdb;
address10.168.3.28:7789;
meta-diskinternal;
}
}



Setup on Primary:
---
1) Created a primary node (VM) [10.168.150.2 (centos6)] with secondary hard
disk /dev/sdb. This disk was filtered in LVM conf.
2a) pvcreate /dev/drbd1
2b) vgcreate VolGroup_DRBD /dev/drbd1
2c) lvcreate --size 20G --name LV_DRBD VolGroup_DRBD
3a) drbdadm create-md r0
3b) drbdadm up r0
3c) drbdadm primary --force r0
4) mkfs.ext3 /dev/drbd1
5) mkdir /db/pgdata
6) mount -t ext3 /dev/drbd1 /db/pgdata
7) cp /root/conf1.xml  /db/pgdata/conf1.xml


Setup on Secondary:
-
1) Created a secondary node (VM) [10.168.3.28 (vm-centos6-dev1)] with
secondary hard disk /dev/vdb. This disk was filtered in LVM conf.
2a) pvcreate /dev/drbd1
2b) vgcreate VolGroup_DRBD /dev/drbd1
2c) lvcreate --size 20G --name LV_DRBD VolGroup_DRBD
3a) drbdadm create-md r0
3b) drbdadm up r0
4) mkfs.ext3 /dev/drbd1
5) mkdir /db/pgdata


Tests and Result:
-
1) To see that file created in step #7 on primary was replicated in
secondary I manually umount partition on primary and demoted the current
primary to secondary:
1a) umount /db/pgdata
1a)drbdadm secondary r0
2) On secondary I manually mounted the partition (mount -t ext3 /dev/drbd1
/db/pgdata) and promoted it to primary (drbdadm primary --force r0)
3) Now I could see file created in step #7 is replicated on secondary as
well.


Problem:

1) How to check that file created on primary was replicated in secondary
without demoting primary and promoting secondary?
2a) How to replicate files on an already mounted filesystem? Example how to
replicate /etc/mydir/myconf.xml or /usr/lib/mydir/mydata which are already
mounted on / (root) partition. In my setup this
   cannot be made DRBD partition.
2b) I tried soft link route (ln -s /etc/mydir/myconf.xml
 /db/pgdata/myconf.xml) but changes made on primary /etc/mydir/myconf.xml
were not replicated on secondary /etc/mydir/myconf.xml
   via the soft link?
2c) How this can be done?


--Raman
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Re: [DRBD-user] DRBD9: full-mesh and managed resources

[Adam Goryachev]

On 18/08/2016 17:47, Roberto Resoli wrote:


Hello,

I'm currently running a three nodes cluster with drbd 9.0.3 and
drbdmanage 0.97.

It happens that in my setup i can dedicate two phisical interfaces per
node to the storage network, and possibly create a "full mesh" network
as of Chapter 5.1.4 of DRBD9 manual
(http://drbd.linbit.com/doc/users-guide-90/ch-admin-manual#s-drbdconf-conns).


The goal is to use only dedicated links (no network switch) for the
storage network connections.

I understand that this network topology is currently not supported by
drbdmanage, and I'm asking if it would be possible to configure the
three storage nodes as usual (one ip address per node) and change the
configuration of the network connections afterwards.

In particular I see that currently is not possible to dedicate an IP for
every different link betwen a managed resource and its peer node.

Am I wrong? Any advice/suggestion?

I can't comment on the DRBD related portions, but can't you add both 
interfaces on each machine to a single bridge, and then configure the IP 
address on the bridge. Hence each machine will only have one IP address, 
and the other machines will use their dedicated network to connect to 
it. I would assume the overhead of the bridge inside the kernel would be 
minimal, but possibly not, so it might be a good idea to test it out.


Regards,
Adam
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[DRBD-user] DRBD9: full-mesh and managed resources

[Roberto Resoli]

Hello,

I'm currently running a three nodes cluster with drbd 9.0.3 and
drbdmanage 0.97.

It happens that in my setup i can dedicate two phisical interfaces per
node to the storage network, and possibly create a "full mesh" network
as of Chapter 5.1.4 of DRBD9 manual
(http://drbd.linbit.com/doc/users-guide-90/ch-admin-manual#s-drbdconf-conns).


The goal is to use only dedicated links (no network switch) for the
storage network connections.

I understand that this network topology is currently not supported by
drbdmanage, and I'm asking if it would be possible to configure the
three storage nodes as usual (one ip address per node) and change the
configuration of the network connections afterwards.

In particular I see that currently is not possible to dedicate an IP for
every different link betwen a managed resource and its peer node.

Am I wrong? Any advice/suggestion?

thanks,
rob
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