Hi all,<br><br>sorry again for disturbing, but I'm still quite confused from the difference between flexible-meta-disk and meta-disk. My concern is I will never use DRBD on top of device that is bigger
than ~50G, so I would like to save metadata space, if it is possible.<br>I was wondering I can simply change all my <br>meta-disk /dev/VolGroup00/drbd_meta[0...] <br>with <br>flexible-meta-disk /dev/VolGroup00/drbd_meta[0...].<br>
<br>But I cannot:<br># drbdadm -d adjust all<br>/etc/drbd.conf:98: Parse error: ';' expected,<br> but got '[' (TK 91)<br><br>Tried to use it without index:<br>flexible-meta-disk /dev/VolGroup00/drbd_meta<br>
# drbdadm -d adjust all<br>/etc/drbd.conf:131: conflicting use of meta-disk 'vsp9.du.rnd.avaya.com:/dev/VolGroup00/drbd_meta[flexible]' ...<br>/etc/drbd.conf:100: meta-disk 'vsp9.du.rnd.avaya.com:/dev/VolGroup00/drbd_meta[flexible]' first used here.<br>
<br>The docs states:<br>"With the <code class="option">flexible-meta-disk</code> keyword you specify
a block device as meta-data storage. You usually use this with LVM,
which allows you to have many variable sized block devices."<br>Does flexible-meta-disk means I have to have one block device per each MD device? If yes, what is the point of the whole flexible-meta-disk definition?<br>
<br>Docs: "You must not use <em class="replaceable"><code>[index]</code></em> with
internal."<br>OK, I'm not using internal at all:<br><br>Next, there is a note there:<br>"Note: Regardless of whether you use the <code class="option">meta-disk</code> or
the <code class="option">flexible-meta-disk</code> keyword, it will always be of
the size needed for the remaining storage size."<br>Does it mean that I do not need to care about using flexible-meta-disk, I can use simple meta-disk and I will only use the space that is required (no fixed 128MB)?<br>
<br>Thanks.<br><br><div class="gmail_quote">2009/3/13 Maros Timko <span dir="ltr"><<a href="mailto:timkom@gmail.com">timkom@gmail.com</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div>Thanks Lars,</div>
<div> </div>
<div>please see comments below.<br></div>
<div class="gmail_quote">2009/3/13 Lars Ellenberg <span dir="ltr"><<a href="mailto:lars.ellenberg@linbit.com" target="_blank">lars.ellenberg@linbit.com</a>></span><div class="im"><br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0px 0px 0px 0.8ex; padding-left: 1ex;">
<div>On Fri, Mar 13, 2009 at 11:01:05AM +0000, Maros Timko wrote:<br>> Hi all,<br>><br>> I wonder why user documentation states how to estimate required DRBD<br>> metadata size for external metadata:<br>
> <a href="http://www.drbd.org/users-guide-emb/ch-internals.html#s-external-meta-data" target="_blank">http://www.drbd.org/users-guide-emb/ch-internals.html#s-external-meta-data</a><br>> when it is quite hardcoded value. At least example drbd.conf file still<br>
> includes this information (128MB for each DRBD resource).<br><br></div>there is meta-disk, and there is flexible-meta-disk.<br><br>man drbd.conf</blockquote>
<div> </div>
</div><div>Wow,</div>
<div>I thought flexible-meta-disk can be used for internal metadata only. I think I saw it somewhere in my first contact with DRBD. Fine, now I checked man drbd.conf and it in place since 8.2.6 so Mea Culpa. I should not simply lean on template drbd.conf<br>
</div><div class="im">
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0px 0px 0px 0.8ex; padding-left: 1ex;"><span></span><br>> So did ahything chance with DRBD 8.3.0 regarding external metadata size<br>
> requirements?<br>
<br></blockquote>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0px 0px 0px 0.8ex; padding-left: 1ex;">with drbd 8.3, you can use up to 16 TiB storage (well, you should not<br>have that exact amount, rather some sectors less).<br>
<br>that would need 512 MiB worth of bitmap, plus the usual few KiB<br>for "superblock" and activity log.<br></blockquote>
<div> </div>
</div><div>But then it is quite interesting. If I am using meta-disk I cannot attach device that is larger then 4TB and if I want to, I simply have to use flexible-meta-disk. I think I have a deja-vu from last December, there was a messages exchange regarding mounting of 16TB devices.</div>
<div> </div>
<div>What if I am using single LVM for multiple flexible-meta-disk devices (flexible-meta-disk /dev/sda6[0...]) and later on I decide to resize/extend the corresponding DRBD partitions - will this be handled by DRBD correctly without any user intervention? Or -- from performance point of view -- would it be prefarable to dump/import all the metadata blocks after such change?</div>
<div> </div>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0px 0px 0px 0.8ex; padding-left: 1ex;"><span></span><br>--<div class="im"><br>: Lars Ellenberg<br>: LINBIT | Your Way to High Availability<br>
: DRBD/HA support and consulting <a href="http://www.linbit.com/" target="_blank">http://www.linbit.com</a><br>
<br>DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.<br>__<br>please don't Cc me, but send to list -- I'm subscribed<br>_______________________________________________<br>drbd-user mailing list<br>
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</div></blockquote>
</div><br>
</blockquote></div><br>