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<DIV>I use the block size = 1024M to test, and found the write performance
is about 100MBps.</DIV>
<DIV> </DIV>
<DIV>
<DIV># dd if=/dev/zero of=test1 bs=1M count=1024 oflag=direct</DIV>
<DIV>1024+0 records in</DIV>
<DIV>1024+0 records out</DIV>
<DIV>1073741824 bytes (1.1 GB) copied, 25.9577 seconds, 41.4 MB/s
-------> this is the bs=1M result</DIV>
<DIV> </DIV>
<DIV># echo 3 > /proc/sys/vm/drop_caches</DIV>
<DIV># dd if=/dev/zero of=test1 bs=1024M count=1 oflag=direct</DIV>
<DIV>1+0 records in</DIV>
<DIV>1+0 records out</DIV>
<DIV> </DIV>
<DIV># echo 3 > /proc/sys/vm/drop_caches</DIV>
<DIV># dd if=/dev/zero of=test1 bs=1024M count=1 oflag=direct</DIV>
<DIV>1+0 records in</DIV>
<DIV>1+0 records out</DIV>
<DIV>1073741824 bytes (1.1 GB) copied, 10.714 seconds, 100 MB/s
---------> this is the bs=1024M result</DIV></DIV>
<DIV> </DIV>
<DIV>I was wondering that is this a normal case? thanks, all</DIV>
<DIV> </DIV>
<DIV>feng</DIV>
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<DIV><SPAN></SPAN> </DIV>
<DIV> </DIV>
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<DIV><B>From:</B> <A href="mailto:themsley@voiceflex.com">Trevor
Hemsley</A></DIV>
<DIV><B>Date:</B> 2012-04-25 23:13</DIV>
<DIV><B>To:</B> </DIV>
<DIV><B>CC:</B> <A
href="mailto:drbd-user@lists.linbit.com">drbd-user@lists.linbit.com</A></DIV>
<DIV><B>Subject:</B> Re: [DRBD-user] drbd write performance slow, per disk
40M/s by dd command</DIV></DIV></DIV>
<DIV>
<DIV class=FoxDiv20120426103501078958>Did you test your network connection to
make sure that it can transfer at a greater speed than that? Maybe it is the
bottleneck - jumbo frames on?<BR><BR>On 25/04/12 15:40, Chris Dickson wrote:
<BLOCKQUOTE
cite=mid:CANSMP-5VwiAOQhfg_0VhQ7dxuFgfQb5F8JkdSghtLfiqJqkGGA@mail.gmail.com
type="cite">
<DIV class=gmail_extra>Also use oflag=direct in both tests and perform them a
few times, sometimes high speeds are the result of caching.<BR><BR>
<DIV class=gmail_quote>On Wed, Apr 25, 2012 at 10:35 AM, Chris Dickson <SPAN
dir=ltr><<A href="mailto:chrisd1100@gmail.com" target=_blank
moz-do-not-send="true">chrisd1100@gmail.com</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<DIV class=gmail_extra>Try turning off disk-barrier and disk-flushes and see
if that makes a difference.
<DIV>
<DIV class=h5><BR><BR>
<DIV class=gmail_quote>2012/4/25 feng zheng <SPAN dir=ltr><<A
href="mailto:zf5984599@gmail.com" target=_blank
moz-do-not-send="true">zf5984599@gmail.com</A>></SPAN><BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<DIV>
<DIV>hi, dear all:<BR><BR>When I use drbd, I found the write performance
very slow, against<BR>testing without drbd module.<BR><BR>1. the
environment:<BR>-) CentOS 5.6<BR>-) 2.6.18 kernel<BR>-) drbd 8.4.1<BR>-)
drbd.conf：<BR>resource r0<BR>{<BR> protocol B;<BR><BR>
net<BR> {<BR>max-buffers 8000;<BR>max-epoch-size
8000;<BR>sndbuf-size 512K;<BR> }<BR><BR>
disk<BR> {<BR> al-extents 3389;<BR>
}<BR><BR><BR> on OSS211<BR> {<BR>
device /dev/drbd0;<BR> disk
/dev/sdb1;<BR> address <A
href="http://192.168.100.231:7788" target=_blank
moz-do-not-send="true"><FONT color=red><B>MailScanner warning: numerical
links are often malicious:</B></FONT> 192.168.100.231:7788</A>;<BR>
meta-disk internal;<BR> }<BR><BR>
on OSS213<BR> {<BR> device
/dev/drbd0;<BR> disk /dev/sde1;<BR>
address <A href="http://192.168.100.213:7788" target=_blank
moz-do-not-send="true"><FONT color=red><B>MailScanner warning: numerical
links are often malicious:</B></FONT> 192.168.100.213:7788</A>;<BR>
meta-disk internal;<BR>
}<BR><BR>}<BR><BR><BR>2. Test scenario:<BR>*) without drbd
module,<BR>dd to write 1G stream into one disk, which formatted to
ext3:<BR>[para]# !echo<BR>echo 3 > /proc/sys/vm/drop_caches<BR>[para]#
!dd<BR>dd if=/dev/zero of=test1 bs=1M count=1000 conv=fdatasync<BR>1000+0
records in<BR>1000+0 records out<BR>1048576000 bytes (1.0 GB) copied,
10.9905 seconds, 95.4 MB/s<BR><BR>*) with drbd module,<BR>dd 1G stream to
the disk, which is ext3 too:<BR>[para]# cat /proc/drbd<BR>version: 8.4.1
(api:1/proto:86-100)<BR>GIT-hash: 91b4c048c1a0e06777b5f65d312b38d47abaea80
build by<BR>root@OSS213, 2012-04-16 21:38:36<BR> 0: cs:Connected
ro:Primary/Secondary ds:UpToDate/UpToDate B r-----<BR>
ns:1260036 nr:0 dw:1260036 dr:297 al:330 bm:0 lo:0 pe:0 ua:0
ap:0<BR>ep:1 wo:b oos:0<BR>[para]#<BR>[para]# dd if=/dev/zero of=test1
bs=1M count=1000 conv=fdatasync<BR>1000+0 records in<BR>1000+0 records
out<BR>1048576000 bytes (1.0 GB) copied, 26.7392 seconds, 39.2
MB/s<BR>[para]# cat /proc/drbd<BR>version: 8.4.1
(api:1/proto:86-100)<BR>GIT-hash: 91b4c048c1a0e06777b5f65d312b38d47abaea80
build by<BR>root@OSS213, 2012-04-16 21:38:36<BR> 0: cs:Connected
ro:Primary/Secondary ds:UpToDate/UpToDate B r-----<BR><BR>All the upper
test writing disk are same. From the upper result, if i<BR>use DRBD to
test, the performance<BR>is 39 MB/s; while if i do not use, the
performance is about 95M/s.<BR><BR>3. My question is:<BR>-) this write
performance decays so large is normal or not?<BR>I had read the following
from the DRBD website:<BR>"15.1. Hardware considerations:<BR>.... A
single, reasonably recent, SCSI or SAS disk will<BR>typically allow
streaming writes of roughly 40MB/s to the single disk."<BR>But this is
very slow.<BR><BR>-）if this is not normal, how can i turn this? is the
config file<BR>something not correct?<BR><BR>thanks a
lot<BR>BRs,<BR>feng<BR></DIV></DIV>_______________________________________________<BR>drbd-user
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moz-do-not-send="true">drbd-user@lists.linbit.com</A><BR><A
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moz-do-not-send="true">http://lists.linbit.com/mailman/listinfo/drbd-user</A><BR></BLOCKQUOTE></DIV><BR></DIV></DIV></DIV></BLOCKQUOTE></DIV><BR></DIV></BLOCKQUOTE><BR></DIV></DIV></BODY></HTML>