Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Fri, May 07, 2004 at 12:04:27PM +0800, Federico Sevilla III wrote:
> Hi everyone,
>
> I have a two-node HA cluster using DRBD for data replication.
> Filesystems are all ext3 in ordered-write mode, DRBD v0.6.12, Linux
> 2.4.26 and Debian GNU/Linux 3.0r2 with DRBD taken direct from
> <http://fsrc.csee.wvu.edu/debian/apt-repository>.
>
> The two machines are connected to each other via GbE with a crossover
> cable. They have two physical hardware SCSI RAID 10 arrays each, and two
> DRBD devices set up, one for each array. One DRBD device is low-traffic,
> used for shared configs. The other DRBD device is used heavily for the
> PostgreSQL database.
>
> During synchronization and when there is heavy database I/O, I get a lot
> of the following messages in my logs on the primary node (interestingly,
> the secondary node doesn't complain at all):
>
> kernel: drbd1: transferlog too small!!
> kernel: drbd1: tl messed up!
> kernel: drbd1: Epoch set size wrong!!found=192 reported=191
>
> I searched the archives and found that this basically means I need to
> tune my drbd.conf file, but isn't something critical. Is this correct?
> Would anyone know of a general tuning and optimization guide for DRBD?
> Or perhaps would anyone be able to spare me some time to comment on my
> DRBD configuration file?
>
> I'm also curious: what's the most reliable way of finding the value to
> put in disk-size? Or can this be omitted for configurations where the
> partitions on both sides are of exactly the same size?
>
> My configuration is as follows:
>
> resource drbd0 {
> protocol = C
> fsckcmd = fsck -p -y
> inittimeout = 60
> disk {
> do-panic
> disk-size = 61522304k
> }
> net {
> sndbuf-size = 1M
note that increasing the sndbuf-size does not neccessarily improve
performance. experiment with this value, maybe even decreasing it helps
performance!
> sync-nice = -20
> sync-min = 4M
> sync-max = 600M
> tl-size = 5000
well, if DRBD complains about tl too small, up this value.
say, 1500, 8000, 12000000 :) until that message no longer triggers.
for further "optimization" you might try to use "jumbo frames" on your
nic, mtu 5000 or some such.
Lars Ellenberg