[DRBD-user] DRBD-8.0 vs DRBD0-0.7.17 performance comparison

[Philipp Reisner]

Hi,

Actually my gut feeling was that drbd-8.0 would perform
better than drbd-0.7.17, since it allows and uses BIOs
up to 32KB of data, while the 0.7 code only allows up
to 4KB of data in a single BIO (that is caused by the 
Linux-2.4.x compatibility)

But on recent hardware, the CPU is so fast that the bigger
BIOs bring no measurable advantage.


CPU:            Intel(R) Pentium(R) D CPU 3.20GHz
ram:            2G
IO subsystem:   3ware Inc 9xxx-series SATA-RAID
Kernel:         rhas4(centOS) 2.6.9-22.EL

[root at node2 tmp]# /root/dm -a 0 -o testfile -s 1G -y -m -p -b 1M

version: 8.0pre2a (api:81/proto:80)
SVN Revision: 2144M build by root at baumeister, 2006-04-12 11:17:47

Full sync:
drbd0: Resync done (total 4372 sec; paused 0 sec; 41388 K/sec)
drbd0: Resync done (total 3995 sec; paused 0 sec; 45296 K/sec)

with filesystem (dm -a 0 -o testfile -s 1G -y -m -p -b 1M): (outer cylinders?)
33.11 MB/sec (1073741824 B / 00:30.930201)
32.06 MB/sec (1073741824 B / 00:31.941736)
32.29 MB/sec (1073741824 B / 00:31.712577)

w/o FS (inner cylinders)
52.30 MB/sec (1073741824 B / 00:19.579340)
54.06 MB/sec (1073741824 B / 00:18.941363)
53.76 MB/sec (1073741824 B / 00:19.047350)

version: 0.7.17 (api:77/proto:74)
SVN Revision: 2093 + GFP_NOIO fix build by root at baumeister, 2006-03-13 
13:19:09

w FS (dm -a 0 -o testfile -s 1G -y -m -p -b 1M): (outer cylinders?)
33.01 MB/sec (1073741824 B / 00:31.020205)
32.55 MB/sec (1073741824 B / 00:31.454737)
32.71 MB/sec (1073741824 B / 00:31.303779)

w/o FS (inner cylinders)
54.13 MB/sec (1073741824 B / 00:18.916885)
54.50 MB/sec (1073741824 B / 00:18.788823)
53.22 MB/sec (1073741824 B / 00:19.240387)

-Philipp
-- 
: Dipl-Ing Philipp Reisner                      Tel +43-1-8178292-50 :
: LINBIT Information Technologies GmbH          Fax +43-1-8178292-82 :
: Schönbrunnerstr 244, 1120 Vienna, Austria    http://www.linbit.com :