[DRBD-user] CentOS 5.2: really bad performance

Achim Stumpf hakim.news at googlemail.com
Mon Oct 6 19:44:50 CEST 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hi,

I have looked up other postings, but didn't find anything which could help me.

Host:
-----

IBM System x3550
RAID bus controller: Adaptec AAC-RAID (Rocket) (rev 02) using Kernelmodul: aacraid
Replicated Storage size is 112Gb
1000Mbit/s network


Kernel: 2.6.18-92.1.13.el5xen
-----------------------------

kernel-xen-2.6.18-92.1.13.el5


DRBD: 8.2.6 (Config file is attached)
-----------

drbd82-8.2.6-1.el5.centos
kmod-drbd82-xen-8.2.6-1.2.6.18_92.1.10.el5


Performance:
------------

=== nc over crosslink ===

<pre>
# dd if=/dev/zero bs=1M count=2000 | nc 192.168.222.29 10000

2000+0 records in
2000+0 records out
2097152000 bytes (2.1 GB) copied, 17.8035 seconds, 118 MB/s
</pre>

Nice Performance.


===  local Test ===

<pre>
# bonnie++ -d /home -s 10000 -r 4000 -u root

Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
syphilis1.fr 10000M 71351  94 102861  19 59725   3 84161  86 153445   1 600.6   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
syphilis1.fra,10000M,71351,94,102861,19,59725,3,84161,86,153445,1,600.6,0,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++
</pre>

Nice local performance on non drbd partition


===  Test only with one node, standalone ===

<pre>
# bonnie++ -d /data1 -s 10000 -r 4000 -u root

Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
syphilis1.fr 10000M  8601  10  8303   1  9849   0 86958  91 160382   2  51.4   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
syphilis1.fra,10000M,8601,10,8303,1,9849,0,86958,91,160382,2,51.4,0,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++
</pre>

Already here the performance is under 10MB/s for block writes. There isn't any traffic on the network card. The second host is not connected.


===  Test with both nodes connected ===

<pre>
# bonnie++ -d /data1 -s 10000 -r 4000 -u root

Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
syphilis1.fr 10000M  8400   9  8595   1 10035   0 79904  84 156880   2  63.0   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ 16780  18
syphilis1.fra,10000M,8400,9,8595,1,10035,0,79904,84,156880,2,63.0,0,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,16780,18
</pre>

the performance is under 10MB/s for block writes, and the second node is connected now.


A sync runs with around:

        [>....................] sync'ed:  3.6% (9784/10140)M
        finish: 0:06:20 speed: 26,296 (22,792) K/sec


What could cause this behavior? How can I get a better performance? 

I have a drbd compiled by myself on the same hardware with my own Kernel under FC7 and it runs with around 50 MB/s. In CentOS it's very sloooow... ;o)

In other postings I have seen that it works with CentOS5, but not my setup.


Thanks,

Achim



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