Re: [Xen-users] Mounting Xen LVM Guests

["Mark Walkom" <markwalkom@xxxxxxxxx>]

All you need to do is;

1. Have a mount point, eg /mnt/tmp
2. mount /dev/xen-system/test01.max /mnt/tmp

That is really all that is needed.
You may need to specify the filesystem, but mount will complain if it needs it.

eg;
root@newnewyork:/mnt/tmp# lvscan|grep utils
  ACTIVE            '/dev/vm-storage/utils-disk' [5.00 GB] inherit
  ACTIVE            '/dev/vm-storage/utils-swap' [512.00 MB] inherit
root@newnewyork:/tmp# mount /dev/vm-storage/utils-disk /mnt/tmp/
root@newnewyork:/tmp# cd /mnt/tmp/
root@newnewyork:/mnt/tmp# ls -l
total 88
drwxr-xr-x  2 root root  4096 2008-07-17 18:17 bin
drwxr-xr-x  2 root root  4096 2006-10-29 00:07 boot
drwxr-xr-x  4 root root  4096 2008-07-17 18:09 dev
drwxr-xr-x 48 root root  4096 2008-12-26 13:07 etc
drwxr-xr-x  3 root root  4096 2008-07-17 18:14 home
drwxr-xr-x  2 root root  4096 2008-06-14 19:19 initrd
drwxr-xr-x  9 root root  4096 2008-07-17 21:27 lib
lrwxrwxrwx  1 root root     4 2008-07-17 18:11 lib64 -> /lib
drwx------  2 root root 16384 2008-06-14 19:15 lost+found
drwxr-xr-x  2 root root  4096 2008-06-14 19:19 media
drwxr-xr-x  2 root root  4096 2006-10-29 00:07 mnt
drwxr-xr-x  2 root root  4096 2008-06-14 19:19 opt
drwxr-xr-x  2 root root  4096 2006-10-29 00:07 proc
drwxr-xr-x  2 root root  4096 2008-09-13 14:25 root
drwxr-xr-x  2 root root  4096 2008-07-17 18:11 sbin
drwxr-xr-x  2 root root  4096 2008-06-14 19:19 srv
drwxr-xr-x  2 root root  4096 2008-01-21 20:33 sys
drwxrwxrwt  2 root root  4096 2008-09-13 14:26 tmp
drwxr-xr-x 10 root root  4096 2008-07-17 18:11 usr
drwxr-xr-x 14 root root  4096 2008-07-17 18:21 var

2009/1/7 Eredicator X <eredicatorx@xxxxxxxxxxxxxxx>

I want to be able to mount LVM partitions that are xen guests when shut down of course.

The reason I can't is cause I am not doing it right. :( I just do not know where I am going wrong.

I start by creating the logical volume

#lvcreate --size 10g --name test01.max /dev/xen-system
#Logical volume "test01.max" created


Install to the new logical volume

#root@max02:/home/virt# virt-install
#Would you like a fully virtualized guest (yes or no)? This will allow you to run unmodified operating systems. yes
#What is the name of your virtual machine? test01.max
#How much RAM should be allocated (in megabytes)? 1000
#What would you like to use as the disk (file path)? /dev/xen-system/test01.max
#Would you like to enable graphics support? (yes or no) yes
#What is the virtual CD image, CD device or install location? /export/home0/erin/ISO/CentOS-5.2-x86_64-netinstall.iso

Finish install

#Guest installation complete... restarting guest.

Shut down new guest

#root@max02:/etc/xen# xm shutdown test01.max

Then try to mount the lvm I found a number of tutorials on how to do this like this;
http://linuxwave.blogspot.com/2008/02/accessing-data-on-xen-lvm-guest-image.html

I tried to stick with the manual from Red Hat and that did not work either;
http://www.centos.org/docs/5/html/Virtualization-en-US/ch-virt-accessing-data.html despite the 2 typos.


#root@max02:~# cd /dev/xen-system/
#root@max02:/dev/xen-system# ls -l
#total 0
#lrwxrwxrwx 1 root root 34 Jan  7 15:25 test01.max -> /dev/mapper/xen--system-test01.max
#
#root@max02:/dev/xen-system# fdisk -lu test01.max
#
#Disk test01.max: 10.7 GB, 10737418240 bytes
#255 heads, 63 sectors/track, 1305 cylinders, total 20971520 sectors
#Units = sectors of 1 * 512 = 512 bytes
#
#     Device Boot      Start         End      Blocks   Id  System
#test01.max1   *          63      208844      104391   83  Linux
#test01.max2          208845    20964824    10377990   8e  Linux LVM
#root@max02:/dev/xen-system# vgscan
#  Reading all physical volumes.  This may take a while...
#  Found volume group "xen-system" using metadata type lvm2
#  Found volume group "VolGroup00" using metadata type lvm2
#root@max02:/dev/xen-system# vgchange -ay xen-system
#  6 logical volume(s) in volume group "xen-system" now active
#root@max02:/dev/xen-system# lvs
#  LV         VG         Attr   LSize   Origin Snap%  Move Log Copy%  Convert
#  LogVol00   VolGroup00 -wi-ao 929.47G
#  LogVol01   VolGroup00 -wi-ao   1.94G
#  test01.max xen-system -wi-a-  10.00G


This is the part I do not understand what am I supposed to be mounting ....
I think the first one should work. But I did not create a file system on /dev/xen-system/test01.max I just installed to it.
I have tried creating a ext3 file system under and then installing to that but was still not able to mount the instance. (Which makes sense to me at least.)

#root@max02:/dev/xen-system# mount /dev/xen-system/test01.max /mnt
#mount: you must specify the filesystem type

#root@max02:/dev/xen-system# mount -t ext3 /dev/xen-system/test01.max /mnt
#mount: wrong fs type, bad option, bad superblock on /dev/xen-system/test01.max,
#       missing codepage or other error
#       In some cases useful info is found in syslog - try
#       dmesg | tail  or so

#root@max02:/dev/xen-system# dmesg | tail
#device vif1.0 entered promiscuous mode
#ADDRCONF(NETDEV_UP): vif1.0: link is not ready
#tun: Universal TUN/TAP device driver, 1.6
#tun: (C) 1999-2004 Max Krasnyansky <maxk@xxxxxxxxxxxx>
#device tap0 entered promiscuous mode
#xenbr0: topology change detected, propagating
#xenbr0: port 4(tap0) entering forwarding state
#tap0: no IPv6 routers present
#hfs: unable to find HFS+ superblock
#VFS: Can't find ext3 filesystem on dev dm-7.

I am sure I am missing something basic here. Can some one please enlighten me?


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