[Ocfs2-users] OCFS2 benchmark slow concurrent write

[Philipp Wehrheim]

Hi everbody,

I've just created a test setup for my company with two pc's drbd (0.8.3)
primary/primary mode with OCFS2 on top of it. the pc's are running suse
10.2 with kernel 2.6.21.2. the Hardware CPU ~1GHz ~12 MBRam and one NIC
(100Mbit).

The setup is working quite stable and so I started to make some
benchmarks and received some strange results:

For the benchmark I used a small C-prog "iotest" that, in a loop, open a
file write on line and closes the file again.

---
#define LOOPCOUNT 1050620
...
  for (i=0; i<LOOPCOUNT; i++) {
    if ( (logFD = open (LOGFILE, O_WRONLY|O_CREAT|O_APPEND, 0666)) !=
-1) {
      write (logFD, logMSG, logLEN);
      close (logFD);
  }
---


1. write to a ext3-fs

	| per line 	  | for 1050620 lines |
hobbes  | 44 nanoseconds  | 47.1 seconds      |
struppi | 37 nanoseconds  | 39.3 seconds      |


2. write to a OCFS2-fs single -> only one maschiene at the time

	| per line 	  | for 1050620 lines |
hobbes  | 84 nanoseconds  | 88.3 seconds      |
struppi | 47 nanoseconds  | 50.1 seconds      |


3. write to a OCFS2-fs into _ONE_ file -> concurrent write from both pcs

	| per line 	   | for 1050620 lines |
hobbes  | 113 milliseconds | 119764 seconds    | yes over 33h
struppi | 113 milliseconds | 119764 seconds    |


4. write to a OCFS2-fs into two files -> each pc into one file

	| per line 	  | for 1050620 lines |
hobbes  | 93,6 nanoseconds  | 98.6 seconds    |
struppi | 59,5 nanoseconds  | 62.6 seconds    |


So as one can see OCFS2 does quite good but when it comes to concurrent
writes into one file it is sloooooowwwwwwww.
The question is now:

- is there an error in my setup
- how can i tune ocfs2
- how can i tune dlm
- WHERE IS THE OCFS2 DOCU???(no im not talking about colorful powerpoint slides)

Thanks in advance
Philipp