On Mon, 2009-07-27 at 18:18 -0400, Ross Walker wrote:
On Jul 27, 2009, at 4:09 PM, Coert Waagmeester lgroups@waagmeester.co.za wrote:
On Mon, 2009-07-27 at 12:37 +0200, Coert Waagmeester wrote:
On Mon, 2009-07-27 at 12:02 +0200, Alexander Dalloz wrote:
On Mon, 2009-07-27 at 08:30 +0200, Coert Waagmeester wrote:
Hello Roman,
I am running drbd 8.2.6 (the standard centos version)
have you considered to test the drbd-8.3 packages?
http://bugs.centos.org/view.php?id=3598
http://dev.centos.org/centos/5/testing/%7Bi386,x86_64%7D/RPMS/
Thank you very much for this tip! It was one very obvious place where I did not look yet.
Would it be necessary to still recompile it for the TCP_NODELAY and such?
I am just making sure, because http://www.nabble.com/Huge-latency-issue-with-8.2.6-td18947965.html makes it seem unnecessary.
Why do the repositories provide both DRBD 8.0.x and 8.2.6?
Here is a status update.... _______________________________________________________________________________ on both hosts I now run from the testing repository: # rpm -qa | grep drbd drbd83-8.3.1-5.el5.centos kmod-drbd83-xen-8.3.1-4.el5.centos _______________________________________________________________________________ Here is my config (slightly condensed):
global { usage-count yes; } common { protocol C; syncer { rate 50M; } net { # allow-two-primaries; } sndbuf-size 0; } # disk {no-disk-flushes; # no-md-flushes; } startup { wfc-timeout 0 ; } } resource xenfilesrv { device /dev/drbd1; disk /dev/vg0/xenfilesrv; meta-disk internal;
on baldur.mydomain.local { address 10.99.99.1:7788; } on thor.mydomain.local { address 10.99.99.2:7788; } } resource xenfilesrvdata { device /dev/drbd2; disk /dev/vg0/xenfilesrvdata; meta-disk internal;
on baldur.mydomain.local { address 10.99.99.1:7789; } on thor.mydomain.local { address 10.99.99.2:7789; } } _______________________________________________________________________________
xenfilesrv is a xen domU in this domU i ran a dd with oflag direct:
# dd if=/dev/zero of=1gig.file bs=1M count=1000 oflag=direct 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB) copied, 147.997 seconds, 7.1 MB/s
Just before I ran the dd this popped up in the secondary hosts syslog:
Jul 27 21:51:42 thor kernel: drbd2: Method to ensure write ordering: flush Jul 27 21:51:42 thor kernel: drbd1: Method to ensure write ordering: flush
What more can I try?
To be quite honest, I have no idea what to do with/ where to find the TCP_NODELAY socket options......
Use drbd option to disable flush/sync, but understand that during a power failure or system crash data will not be consistent on disk and you will need to sync the storage from the other server.
-Ross
CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
That also does not really make a difference. According to DRBD everything goes into barrier mode.
I still get speed of around 7.5 MB/sec
In the config i now have this: disk { no-disk-barrier; no-disk-flushes; no-md-flushes; }
according to /proc/drbd it then goes into 'drain' mode.
I still get only 8MB/sec throughput.
Would it be unwise to consider using Protocol A?
I have just tried Protocol A, and I also only get 8 MB/sec. But, if I disconnect the secondary node, and do the dd again, I get 32MB/sec!
PS I sent another mail with an attachment. Have a feeling that is moderated though....