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<div class="moz-cite-prefix">Hi all,<br>
<br>
it seems my attachments were blocked, sending again.<br>
<br>
I'm trying to set up DRBD to use with KVM virtual machines so that
I can have physical redundancy on my services. I followed this to
use LVM volumes as my DRBD backing device: <a
href="http://www.drbd.org/users-guide-8.3/s-lvm-lv-as-drbd-backing-dev.html">http://www.drbd.org/users-guide-8.3/s-lvm-lv-as-drbd-backing-dev.html</a>
and then did this <a
href="http://www.drbd.org/users-guide-8.3/s-first-time-up.html">http://www.drbd.org/users-guide-8.3/s-first-time-up.html</a>
to enable the resource r0.<br>
<br>
I did the initial device synchronization as per this: <a
href="http://www.drbd.org/users-guide-8.3/s-initial-full-sync.html">http://www.drbd.org/users-guide-8.3/s-initial-full-sync.html</a>
and got the expected results. I actually did this twice for 2
resources, it took a while but eventually reported the 20GB
volumes as:<br>
<blockquote><tt>root@kvm-srv-01:~# cat /proc/drbd </tt><tt><br>
</tt><tt>version: 8.3.11 (api:88/proto:86-96)</tt><tt><br>
</tt><tt>srcversion: 41C52C8CD882E47FB5AF767 </tt><tt><br>
</tt><tt><br>
</tt><tt> 1: cs:Connected ro:Primary/Secondary
ds:UpToDate/UpToDate C r-----</tt><tt><br>
</tt><tt> ns:0 nr:0 dw:0 dr:1220 al:0 bm:0 lo:0 pe:0 ua:0
ap:0 ep:1 wo:f oos:0</tt><tt><br>
</tt><tt> 2: cs:Connected ro:Secondary/Primary
ds:UpToDate/UpToDate C r-----</tt><tt><br>
</tt><tt> ns:20970844 nr:0 dw:0 dr:20971696 al:0 bm:1280 lo:0
pe:0 ua:0 ap:0 ep:1 wo:f oos:0</tt><br>
</blockquote>
and <br>
<blockquote><tt>root@kvm-srv-02:~# cat /proc/drbd</tt><tt><br>
</tt><tt>version: 8.3.11 (api:88/proto:86-96)</tt><tt><br>
</tt><tt>srcversion: 41C52C8CD882E47FB5AF767 </tt><tt><br>
</tt><tt><br>
</tt><tt> 1: cs:Connected ro:Secondary/Primary
ds:UpToDate/UpToDate C r-----</tt><tt><br>
</tt><tt> ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0
ep:1 wo:f oos:0</tt><tt><br>
</tt><tt> 2: cs:Connected ro:Primary/Secondary
ds:UpToDate/UpToDate C r-----</tt><tt><br>
</tt><tt> ns:0 nr:20970844 dw:20970844 dr:672 al:0 bm:1280
lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0</tt><br>
</blockquote>
The 2 resources are each to be used for testing guest Virtual
Machine(s) with KVM/DRBD. In the first instance I installed the
guest before creating the DRBD block device and after
synchronization all the files were available to use in a VM. In
the second resource I created the DRBD block device before
installing the VM. I did this because I want to be both creating
new VMs and migrating existing ones to DRBD.<br>
<br>
What I'm seeing is that changes to the primary do not seem to be
on the secondary. My understanding is that using Single Primary
mode with Protocol C should mean that all disk writes to the
primary should be complete after a successful write on the
secondary.<br>
<br>
If the writes are going to both nodes shouldn't I see non zero
values for Disk reads and Disk writes in <tt>/proc/drbd</tt><tt>?<br>
</tt><br>
Perhaps the issue is that I'm using the LVM volumes directly for
my KVM VMs. I'm not sure if I should be approaching this with a
nested approach like this <a
href="http://www.drbd.org/users-guide-8.3/s-nested-lvm.html">http://www.drbd.org/users-guide-8.3/s-nested-lvm.html</a>
<br>
<br>
Does anyone have any thoughts on why my data doesn't seem to be
replicating or perhaps point me in the right direction for how to
dig a little deeper. My limited understanding is that DRBD should
be between my host and the LVM volume but perhaps it's writing
directly to the LV and not going through DRBD.<br>
<br>
Thanks in advance.<br>
<br>
<a href="http://www.tracker-software.com/downloads/"></a>
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<div style="font-family:Arial;font-size:12px">
<p><strong>Paul O’Rorke</strong><br>
Tracker Software Products<br>
<a href="mailto:paul.ororke@tracker-software.com">paul@tracker-software.com</a><br>
</p>
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