Hello everybody
After 3 days messing around I'm at my wits' end. I have two Sun X4200M2
servers which I would like to setup as Xen dom0s with a drbd-mirrored
file system for paravirtualized domU images.
I setup an LVM2 on top of DRBD to create the domU volumes and to be able
to backup the domUs with LVM snapshot.
I was able to configure this setup and make it run, but when accessing
the block-frontend device in domU this is terrible slow. E.g. copying a
5G file via scp and gigabit Ethernet onto the domU leads to a lot of
stalls during transfer. The peak transfer rate is about 5MB/s every 1-2
minutes but generally it's about a few hundred KB/s. When copying the
same file onto the DRBD volume mounted directly in dom0 it works with
the expected 30-40MB/s. Another test was to sync the portage tree but
also this takes maybe about 20 minutes or spontaneously raises some
timeout errors. Sometimes after a while the disk fully detaches from the
domU, so every call of a binary in domU leads to a Input/output error.
I guess the domU kernel adds this troubles, but why? There are no
statements in any log files. E.g. /var/log/xen/xend-debug.log doesn't
notify the detached block device.
I use Gentoo Linux and tried so far with xen-3.1.2 and xen-3.2.0,
xen-sources-2.6.18-r8, xen-sources-2.6.20-r6 and xen-sources-2.6.22,
drbd-8.0.7, drbd-8.0.8 and drbd-8.0.11.
The longer the more I expect a general problem with Xen and this setup,
a kernel problem or a misconfiguration. Attached are the most important
configurations for this setup.
Are there any hints or other experiences for such a setup? All ideas are
welcome.
Thanks for reading and giving any hints...
Cheers Reto Gantenbein
Configurations #
/etc/drbd.conf
,
| global {
| usage-count no;
| dialog-refresh 1;
| }
|
| common {
| startup {
| wfc-timeout 60;
| degr-wfc-timeout 60;
| }
|
| disk {
| on-io-error detach;
| # also tried 'pass-on' with same behavior
| }
|
| syncer {
| rate 500M;
| al-extents 80;
| }
| }
|
| resource gentoo {
| protocol C;
| net {
| # required for xen live migration
| allow-two-primaries;
| after-sb-0pri discard-zero-changes;
| after-sb-1pri discard-secondary;
|}
|
|on vserver03 {
| device/dev/drbd1;
| disk /dev/xen-vg/gentoo;
| address 10.0.0.1:7789;
| meta-disk internal;
|}
|
|on vserver04 {
|device /dev/drbd1;
|disk /dev/xen-vg/gentoo;
|address10.0.0.2:7789;
|meta-disk internal;
|}
| }
`
/etc/xen/gentoo
,
| name = gentoo
|
| kernel = /cluster/xen/kernel/vmlinuz-gentoo-domU
| extra =
| root = /dev/hda1
|
| memory = 4096
| vcpus = 3
| disk = [ 'drbd:gentoo,hda1,w' ]
| vif = [ 'mac=00:40:a6:00:45:01,bridge=xenbr-core',
| 'mac=00:40:a6:00:45:02,bridge=xenbr-public' ]
`
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