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Cameron Smith wrote:
<blockquote
cite="mid:edc0e50f1003171829y1ac03c93l9aa900c308e679e2@mail.gmail.com"
type="cite">Still a little fuzzy about where my data can go in
relation to drbd.
<div><br>
</div>
<div>My lower level is:</div>
<div>/dev/sda2 /data</div>
<div><br>
</div>
<div>my drbd device is:</div>
<div>/dev/drbd1</div>
<div><br>
</div>
<div>The docs say not to access the lower level device after drbd is
running so where do I put my files and data?</div>
<div>If it's actually on the drbd1 device how to I access that? I
cannot mount it like a partition using mount.</div>
<div><br>
</div>
<div>My config still looks like:</div>
<div><br>
</div>
<div><span class="Apple-style-span"
style="font-family: arial,sans-serif; font-size: 13px; border-collapse: collapse;">
<div>global {</div>
<div> usage-count yes;</div>
<div>}</div>
<div>common {</div>
<div> protocol C;</div>
<div>}</div>
<div>resource r0 {</div>
<div> on <a moz-do-not-send="true" href="http://clst01.example.net/"
target="_blank" style="color: rgb(28, 81, 168);">clst01.example.net</a> {</div>
<div> device /dev/drbd1;</div>
<div> disk /dev/sda2;</div>
<div> address <a moz-do-not-send="true"
href="http://10.233.2.71:7789/" target="_blank"
style="color: rgb(28, 81, 168);">10.233.2.71:7789</a>;</div>
<div> meta-disk /dev/sda6[0];</div>
<div> }</div>
<div> on <a moz-do-not-send="true" href="http://clst02.example.net/"
target="_blank" style="color: rgb(28, 81, 168);">clst02.example.net</a> {</div>
<div> device /dev/drbd1;</div>
<div> disk /dev/sda2;</div>
<div> address <a moz-do-not-send="true"
href="http://10.233.2.72:7789/" target="_blank"
style="color: rgb(28, 81, 168);">10.233.2.72:7789</a>;</div>
<div> meta-disk /dev/sda6[0];</div>
<div> }</div>
<div>}</div>
<div><br>
</div>
</span></div>
<br>
</blockquote>
drbd only allows nodes that are "primary" for a resource to access, and
mount, the block device presented by drbd (in your case, /dev/drbd1).
in the default "primary/secondary" mode, there is only one primary
which can access the device then mount it. to use the device on the
secondary, you must promote it the the primary (which will also demote
the current primary) and then mount the filesystem. this can be handled
by linux-ha or pacemaker automatically for you. you can't mount it on
both servers at once. and mounting the underlying block device on the
secondary can cause data corruption since you essentially have a block
device mounted twice.<br>
<br>
you can get around this by using "primary/primary" mode but will
require significant changes to your system. you will have to use a
clustered filesystem, such as GFS or OCFS, for your /data/ mount point.
this introduces its own can of worms but is possible.<br>
<br>
drbd does not magically make it so that any filesystem can magically
become clustered and redundant and it wont be able to since it has no
concept of a filesystem. from a high level, it just replicates writes
between block devices on two servers.<br>
<br>
hope that helps clarify things a little more for you.<br>
<br>
mike<br>
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