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<p class="MsoNormal">I have 6 x Samsung SSD 840 pro drives in an RAID 0 configuration (mdraid).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When I write to a non-DRBD partition on the drive, bypassing caches, I get 400 MB/sec.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When I trim a filesystem mounted on a non-DRBD partition, it finishes fast.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When I write to a DRBD replicated volume, I get 80MB/sec, which is about when I would expect using protocol C over a gigabit network.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When I trim a filesystem that is mounted on a drbd device it is extremely slow. It takes three days to trim a 1.2TB volume.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Running iperf between nodes shows 900Mbits/sec bandwidth, <1 ms latency, no packet loss. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Why is trimming a DRBD volume so slow? This makes the servers unusable.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">--<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Eric Robinson<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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