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<DIV>hi, dear all:</DIV>
<DIV> </DIV>
<DIV style="TEXT-INDENT: 2em">When I use drbd, I found the write performance
very slow, against testing without drbd module.</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">1. the environment:</DIV>
<DIV style="TEXT-INDENT: 2em">-) CentOS 5.6 </DIV>
<DIV style="TEXT-INDENT: 2em">-) 2.6.18 kernel</DIV>
<DIV style="TEXT-INDENT: 2em">-) drbd 8.4.1</DIV>
<DIV style="TEXT-INDENT: 2em">-) drbd.conf£º</DIV>
<DIV style="TEXT-INDENT: 4em">
<DIV style="FONT-STYLE: italic">resource r0 </DIV>
<DIV style="FONT-STYLE: italic">{</DIV>
<DIV style="FONT-STYLE: italic"> protocol B;</DIV>
<DIV style="FONT-STYLE: italic"> </DIV>
<DIV style="FONT-STYLE: italic"> net</DIV>
<DIV style="FONT-STYLE: italic"> { </DIV>
<DIV style="FONT-STYLE: italic">max-buffers 8000;</DIV>
<DIV style="FONT-STYLE: italic">max-epoch-size 8000;</DIV>
<DIV style="FONT-STYLE: italic">sndbuf-size 512K;</DIV>
<DIV style="FONT-STYLE: italic"> }</DIV>
<DIV style="FONT-STYLE: italic"> </DIV>
<DIV style="FONT-STYLE: italic"> disk</DIV>
<DIV style="FONT-STYLE: italic"> {</DIV>
<DIV style="FONT-STYLE: italic"> al-extents 3389;</DIV>
<DIV style="FONT-STYLE: italic"> }</DIV>
<DIV style="FONT-STYLE: italic"> </DIV>
<DIV style="FONT-STYLE: italic"> </DIV>
<DIV style="FONT-STYLE: italic"> on OSS211</DIV>
<DIV style="FONT-STYLE: italic"> {</DIV>
<DIV
style="FONT-STYLE: italic"> device /dev/drbd0;</DIV>
<DIV
style="FONT-STYLE: italic"> disk /dev/sdb1; </DIV>
<DIV
style="FONT-STYLE: italic"> address 192.168.100.231:7788;</DIV>
<DIV
style="FONT-STYLE: italic"> meta-disk internal;</DIV>
<DIV style="FONT-STYLE: italic"> }</DIV>
<DIV style="FONT-STYLE: italic"> </DIV>
<DIV style="FONT-STYLE: italic"> on OSS213</DIV>
<DIV style="FONT-STYLE: italic"> {</DIV>
<DIV
style="FONT-STYLE: italic"> device /dev/drbd0;</DIV>
<DIV
style="FONT-STYLE: italic"> disk /dev/sde1;</DIV>
<DIV
style="FONT-STYLE: italic"> address 192.168.100.213:7788;</DIV>
<DIV
style="FONT-STYLE: italic"> meta-disk internal;</DIV>
<DIV style="FONT-STYLE: italic"> }</DIV>
<DIV style="FONT-STYLE: italic"> </DIV>
<DIV style="FONT-STYLE: italic">}</DIV>
<DIV> </DIV></DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">2. Test <FONT size=2>scenario</FONT>:</DIV>
<DIV style="TEXT-INDENT: 2em">*) without drbd module,</DIV>
<DIV style="TEXT-INDENT: 4em">dd to write 1G stream into one disk, which
formatted to ext3:</DIV>
<DIV style="TEXT-INDENT: 4em">
<DIV>[para]# !echo</DIV>
<DIV>echo 3 > /proc/sys/vm/drop_caches </DIV>
<DIV>[para]# !dd</DIV>
<DIV>dd if=/dev/zero of=test1 bs=1M count=1000 conv=fdatasync</DIV>
<DIV>1000+0 records in</DIV>
<DIV>1000+0 records out</DIV>
<DIV>1048576000 bytes (1.0 GB) copied, 10.9905 seconds, 95.4 MB/s</DIV></DIV>
<DIV style="TEXT-INDENT: 4em"> </DIV>
<DIV style="TEXT-INDENT: 2em">*) with drbd module,</DIV>
<DIV style="TEXT-INDENT: 4em">dd 1G stream to the disk, which is ext3 too:</DIV>
<DIV style="TEXT-INDENT: 4em">
<DIV style="FONT-STYLE: italic">[para]# cat /proc/drbd </DIV>
<DIV
style="FONT-STYLE: italic">version: 8.4.1 (api:1/proto:86-100)</DIV>
<DIV
style="FONT-STYLE: italic">GIT-hash: 91b4c048c1a0e06777b5f65d312b38d47abaea80 build by root@OSS213, 2012-04-16 21:38:36</DIV>
<DIV
style="FONT-STYLE: italic"> 0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate B r-----</DIV>
<DIV
style="FONT-STYLE: italic"> ns:1260036 nr:0 dw:1260036 dr:297 al:330 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0</DIV>
<DIV style="FONT-STYLE: italic">[para]# </DIV>
<DIV
style="FONT-STYLE: italic">[para]# dd if=/dev/zero of=test1 bs=1M count=1000 conv=fdatasync</DIV>
<DIV style="FONT-STYLE: italic">1000+0 records in</DIV>
<DIV style="FONT-STYLE: italic">1000+0 records out</DIV>
<DIV
style="FONT-STYLE: italic">1048576000 bytes (1.0 GB) copied, 26.7392 seconds, 39.2 MB/s</DIV>
<DIV style="FONT-STYLE: italic">[para]# cat /proc/drbd </DIV>
<DIV
style="FONT-STYLE: italic">version: 8.4.1 (api:1/proto:86-100)</DIV>
<DIV
style="FONT-STYLE: italic">GIT-hash: 91b4c048c1a0e06777b5f65d312b38d47abaea80 build by root@OSS213, 2012-04-16 21:38:36</DIV>
<DIV
style="FONT-STYLE: italic"> 0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate B r-----</DIV></DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">All the upper test writing disk are same.
>From the upper result, if i use DRBD to test, the performance </DIV>
<DIV style="TEXT-INDENT: 2em">is 39 MB/s; while if i do not use,
the performance is about 95M/s.</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 4em">
<DIV style="TEXT-INDENT: 2em">3. My question is:</DIV>
<DIV style="TEXT-INDENT: 2em">-) this write performance decays so large is
normal or not? </DIV>
<DIV style="TEXT-INDENT: 2em">I had read the following from the DRBD website:
</DIV>
<DIV style="TEXT-INDENT: 6em">"15.1. Hardware considerations: </DIV>
<DIV style="TEXT-INDENT: 6em">.... A single, reasonably recent, SCSI or
SAS disk will </DIV>
<DIV style="TEXT-INDENT: 6em">typically allow streaming writes of roughly 40MB/s
to the single disk."</DIV>
<DIV style="TEXT-INDENT: 2em">But this is very slow.</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">-£©if this is not normal, how can i turn this? is
the config file something not correct?</DIV>
<DIV style="TEXT-INDENT: 2em"> </DIV>
<DIV style="TEXT-INDENT: 2em">thanks a lot</DIV>
<DIV style="TEXT-INDENT: 2em">BRs,</DIV>
<DIV style="TEXT-INDENT: 2em">feng</DIV></DIV></DIV></BODY></HTML>