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<font size="-1"><font face="Cambria">I will re-read the DRBD
Funadmentals- the way I understood it was basically if you were
writing to node1 it wouldn't put the data through a TCP socket
and would actually just write directly to the block device and
that TCP was usually only used for the actual replicating and
data integrity conversation between the hosts. My understanding
now is that for all hosts included in the resource definition it
will put the data into that socket - including the host you're
writing from (eg: if I wrote to /dev/drbd0 on host1 it will go
through the socket to write the data still to write it to the
underlying block device- I had originally thought it would skip
the TCP socket write and write directly to the block device). <br>
<br>
I hope that was clear? It probably doesnt make sense because my
original understanding was wrong :) <br>
<br>
<br>
</font></font>
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Regards, <br>
Chuck Kozler<br>
<i>Lead Infrastructure & Systems Administrator</i><br>
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On 10/12/2011 2:09 PM, Florian Haas wrote:
<blockquote cite="mid:4E95D7C3.2000503@hastexo.com" type="cite">
<pre wrap="">On 2011-10-12 20:00, Charles Kozler wrote:
</pre>
<blockquote type="cite">
<pre wrap="">This was 100% spot on the answer I was looking for- thanks guys!
Also, do any white papers exist on how DRBD works on the inside? From
what you told me it looks like its
</pre>
</blockquote>
<pre wrap="">
Um, "DRBD Internals" in the DRBD User's Guide? You can also check out
the Publications sections in that same guide; but those are most likely
of interest to kernel developers only. But don't let that scare you,
dive right in if you're so inclined. :)
</pre>
<blockquote type="cite">
<pre wrap="">Write to DRBD Block Device -> Write to TCP buffer -> Write to host disks
I thought it was
Write DRBD Block Device -> Write to disk -> Write to TCP Buffer -> Write
to host disks (like a push method almost)
</pre>
</blockquote>
<pre wrap="">
So what's the difference between "Write to disk" and "Write
to host disks" in your model?
The actual pattern is also described in the User's Guide; see the
chapter named "DRBD Fundamentals".
</pre>
<blockquote type="cite">
<pre wrap="">Which is why I wanted to know about disk corruption but from what it
seems like is that I should be more concerned about corruption in the
network stack, right?
</pre>
</blockquote>
<pre wrap="">
No you should be concerned about both, because your users will eat you
alive if you present them broken data, no matter the source of breakage.
Cheers,
Florian
</pre>
</blockquote>
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