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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 moz-do-not-send="true"
href="mailto:chrisd1100@gmail.com" target="_blank">chrisd1100@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<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 moz-do-not-send="true"
href="mailto:zf5984599@gmail.com"
target="_blank">zf5984599@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<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 moz-do-not-send="true"
href="http://192.168.100.231:7788"
target="_blank"><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 moz-do-not-send="true"
href="http://192.168.100.213:7788"
target="_blank"><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>
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