[DRBD-user] Why is drbd 0.7.22 slow on Opteron 240 EE?

Maurice Volaski mvolaski at aecom.yu.edu
Tue Nov 21 09:39:01 CET 2006

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


I have two new computers raided by drbd.

Primary
1 Opteron 265 HE
2 GB RAM (PC3200)
4 Seagate 750 GB SATA drives
PCIe Areca 1220 card (raid 6)
builtin broadcom gigabit ethernet with MTU of 9000
64-bit kernel 2.6.18-gentoo-r1 with areca driver, set to deadline scheduler

Secondary
1 Opteron 240 EE
1 GB RAM (PC2700)
3 Seagate 750 GB SATA drives
PCIe Areca 1210 card (raid 5)
builtin broadcom gigabit ethernet with MTU of 9000
64-bit kernel 2.6.18-gentoo-r1 with areca driver, set to deadline scheduler

The computers are connected via a Netgear GS724, with jumbo frames 
setting turned on.

The relevant drbd.conf on both computers is
net     {
                         timeout 60;
                         connect-int 10;
                         ping-int 10;
                         ko-count 4;
                         max-buffers 32768;
                         max-epoch-size 2048; 
                         sndbuf-size 1M;
                 }
syncer  {
                         rate 100M;
                         group 2;
                         al-extents 257;
	}


On fresh sync of /dev/drbd2, which is 1.4 TB, I'm seeing an average 
20.3 MB per second. When I test with ttcp, I routinely see about 64 
MB per second. Write tests with dd if=/dev/zero 
of=/maurice/bonnie/hello bs=400M count=10 appear to show a write 
speed on the secondary of about 160 MB  per second, so it doesn't 
appear that the secondary has any obvious I/O bottleneck.

So shouldn't drbd be much faster than it actually is?

I also notice that the secondary is often unresponsive to command 
line commands and I see messages in the log of the primary:
drbd2: [drbd2_worker/9750] sock_sendmsg time expired, ko = 3
-- 

Maurice Volaski, mvolaski at aecom.yu.edu
Computing Support, Rose F. Kennedy Center
Albert Einstein College of Medicine of Yeshiva University



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