<div class="gmail_quote">On Thu, Apr 30, 2009 at 5:18 PM, Tom Brown <span dir="ltr"><<a href="http://wc-linbit.com">wc-linbit.com</a>@<a href="http://vmail.baremetal.com">vmail.baremetal.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br>
I'd expect that if he's seeing sync's running faster than application<br>
level writes, then there is an issue with write-barriers. DRBD is taking<br>
steps to provide write-ordering protection, which aren't relevent to<br>
bulk/block copying of re-syncing.<br>
<br>
e.g. <a href="http://www.drbd.org/users-guide/re-drbdconf.html" target="_blank">http://www.drbd.org/users-guide/re-drbdconf.html</a><br>
no-disk-barrier , no-disk-flushes , no-disk-drain</blockquote><div><br>I've generally established that for best performance on my hardware, I need no-disk-flushes, no-md-flushes, and no-disk-barrier, and they've all been in place already. no-disk-drain does not improve anything, and was mentioned by Lars as a bad idea if the other three are present. <br>
<br>The connection is capable of at least ~900MB/s (Infiniband), and the top observed DRBD sync speed is 400MB/s as mentioned. For testing purposes, the metadata is on a ramdisk.<br><br>Thanks,<br><br>-Gennadiy<br></div></div>