[Fedora-xen] automated disksetup after kickstart installation for xenguest ??

Thomas von Steiger thomas.vonsteiger at bluewin.ch
Mon Jun 4 22:28:37 UTC 2007


Hello,

I have tested howto auto setup a xenguest after the kickstart job.
For this i start a first script in /etc/rc.local when the xen guest makes
the first boot.
Special point howto make additional filesystems on additional xen guest
disks.
As disk's (xvd devices) we use dom0 lv's for xenguest.

Dom0 is RHEL5 and domU RHEL4U5 para.

I found several points about this:

- using "sfdisk" to make the guest partition on xvdb.
To write a partition table with sfdisk we need first the disk geometrie for
calculation of the disksize.
With "sfdisk -g /dev/xvdb" I get message "Disk /dev/xvdb: cannot get
geometry". -> nok

- using "parted", i'm able to write the partition table to /dev/xvdb. -> ok
After this "partprobe" should reload partition table in the kernel.  --> nok
The problem, partprobe don't reload partition created with parted.
The only way is to reboot again the guest. Because this is not practical for
automated server setup.

- to only way for now is to use /dev/xvdb without partition, direct
"pvcreate /dev/xvdb".
If dom0 reboots or vgscan is running on dom0, i found in dom0 all the vg's
and lv's on disk's without partitions from the xen guest's. So I can
vgchange -a y "xenguest vg" on dom0 and mount this lv because this lv is
online in his xen guest.
Maybe this is a feature to backup xenguests or a bug to corrupt filesystems
if there is a wrong handling.
I have not tested what happens if i have 10 xen guest's and each xenguest
has a vg with the same name.

Manual i can always use fdisk and partprobe to create vg,lv's and fs without
reboot.
xvd devices with a partition can not be detected from dom0.

Has anybody tested similar setup's ?
Should i open bugzilla's for this 3 points ?

Many Tanks,
Thomas





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