Hello, Jan.


If you are using 2.6.18 kernel you can disable DEVFS.

Follow this steps to ensure that you don't have forgot anything.

http://wiki.xen-br.org/index.php?title=Xen-ha



Em 15:30, Jan Kellermann   escreveu:

Hi,

we have 2 servers on centos5.2 in a cluster with the redhat cman in the
configuration

SERVER1 > LVM \
CMAN DRBD > XEN
SERVER2 > LVM /

For each xen we create a new local LVM on each node, put them in a drbd
and install an os (debian 4 or ubuntu 8). The xens are running as pvm.

Everything works fine since over 4 months now.

But we have some performance-Problems:

Writing on the Xen-devices produces an iowait about 50 to 60% on the
xen-processors.

we ha ve 3 szenarios tested:

a) Xen on DRBD
b) Xen on DRBD but disconnected
c) direct mounted DRBD

You can see the difference in Write pro Char and Write per Block.

a: 3792 / 4011
b: 52037 / 103777
c: 57135 / 325002

See bonnie_result.txt for more data.

We attached our drbd.conf and a xen-config for your information.

The Server are each 2xDual-Core AMD Opteron(tm) Processor 2214 HE with
32 Gb RAM and 2TB-Harddrive on Raid5 running von CentOS 5.2. The
XEN-DomUs are Debian 4 or Ubuntu 8. The NICs are bonded Intel 1GBit. For
the DRBD we have an own connection on a seperately subnet.

Though we are wondering what there happens. Any Idea?

And: YES, we tried a some configurations in the last past months before
we are asking you today :)

Best regards an Thank you in advance
Jan