See this page for a good story about it .. Some highlights: (more…)
Sep
15
2008
15
2008
Mounting an LVM Logical Volume in an Oracle VM Disk Image
# losetup /dev/loop0 System.img
# kpartx -a /dev/loop0
# ls -l /dev/mapper/loop0*
brw-rw—- 1 root disk 253, 0 Jul 14 19:57 /dev/mapper/loop0p1
brw-rw—- 1 root disk 253, 1 Jul 14 19:57 /dev/mapper/loop0p2
# file -s /dev/mapper/loop0p2
/dev/mapper/loop0p2: LVM2 (Linux Logical Volume Manager) , UUID: 7zKduhTHsMa3YD3t2gocYKUDGRP5QvW
# vgscan
Reading all physical volumes. This may take a while…
Found volume group “VolGroup00” using metadata type lvm2
# vgchange -a y VolGroup00
2 logical volume(s) in volume group “VolGroup00” now active
# lvdisplay
— Logical volume —
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID YcNYud-4BXO-Ro6N-P7VW-yrLm-DDZT-oLGgAO
LV Write Access read/write
LV Status available
# open 0
LV Size 1.94 GB
Current LE 62
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:2
— Logical volume —
LV Name /dev/VolGroup00/LogVol01
VG Name VolGroup00
LV UUID pSyXMZ-8TXw-fwiw-m3re-Oi3I-0fch-mJ1Q5H
LV Write Access read/write
LV Status available
# open 0
LV Size 1.91 GB
Current LE 61
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 253:3
# mkdir -p /mnt/VolGroup00/LogVol00
# mount /dev/VolGroup00/LogVol00 /mnt/VolGroup00/LogVol00
# ls /mnt/VolGroup00/LogVol00
bin dev home lib lost+found misc opt root selinux sys usr
boot etc initrd lib64 media mnt proc sbin srv tmp var
#
Sep
15
2008
15
2008
Is there a way to somehow mount a (shutdown) Xen disk image and browse files?
Yes .. Many .. One is
# losetup /dev/loop0 System.img
# kpartx -a /dev/loop0
# ls -l /dev/mapper/loop0*
brw-rw—- 1 root disk 253, 0 Jul 14 18:53 /dev/mapper/loop0p1
brw-rw—- 1 root disk 253, 1 Jul 14 18:53 /dev/mapper/loop0p2
# mount /dev/mapper/loop0p2 /mnt
Another is
# fdisk -l -u System.img
…
Device Boot Start End Blocks Id System
System.img1 * 63 208844 104391 83 Linux
System.img2 208845 8385929 4088542+ 83 Linux
# echo 208845\*512 | bc
106928640
# mount -o loop,offset=106928640 System.img /mnt
But those will not work for partitions which are LVM .. like:
# fdisk -l -u System.img
Disk System.img: 0 MB, 0 bytes
255 heads, 63 sectors/track, 0 cylinders, total 0 sectors
Units = sectors of 1 * 512 = 512 bytes
Device Boot Start End Blocks Id System
System.img1 * 63 208844 104391 83 Linux
System.img2 208845 8385929 4088542+ 8e Linux LVM
mount fails with:
mount: you must specify the filesystem type
or
ioctl: LOOP_SET_STATUS: Invalid argument
(if you use an offset mount)
I am pretty sure that there is a way to mount the logical volumes under that LVM
from dom0 .. Need to investigate..
BTW
this is not supposed to work also if the filesystem is encrypted.. That
requires encryption arguments to be passed along too.. That is rreally
advised for the sake of security.
Sep
15
2008
15
2008
Xen Kernel Hangs booting Dom0 at Relinquishing VGA console
Xen Kernel Hangs booting Dom0 at Relinquishing VGA console
Any kernel I have tested from fedora since 2.6.23 had this issue .. Need some time to really work on it ..
Sep
15
2008
15
2008
Xen: How to define the boot order for HVM in vm.cfg
This is done by the boot paramer in vm.cfg.
The switches are:
* floppy (a)
* hard disk (c)
* Network (n)
* CD-ROM (d)
If you use
boot = ‘n’
it will be stuck at PXE boot even if there is no dhcp lease and guest will not attempt boot from the Virtual Disk.
To be able to have an order, you need to concatenate the switches. e.g. if you need to have a boot order like
1. network (n)
2. harddisk (c)
3. cdrom (d)
you need to have
boot=”ncd”
in vm.cfg.
Moreover,
If somehow the TFTP server is not accessible or misconfigured, that will fail
over to “c” aka. disk..
But if the DHCP server is not available, the boot will be stuck in a loop of “No
IP address”. Actually this is not much different from a normal BIOS.. A couple
of Dell systems with IBA (Intel Boot Agent) behaves similarly, but only
providing keystroke options.
I’ll also check the behaviour model of pypxeboot too ..
