3:45 a.m.
Then I created my blank 'disk' file and tried to
run virt-rescue on it. It crashed out with an
error from febootstrap.
First of all, debug this properly:
(1) What is the full error message?
(2) What is the complete, unedited output of 'libguestfs-test-tool'?
(3) What version of libguestfs & febootstrap are using and where did
you get them from?
You can post the details on our mailing list libguestfs(a)redhat.com
(no need to subscribe if you don't want to).
After finding nothing terribly
useful or current on this in searching, I tried
guestfish instead. After some fiddling I got it
to attach my blank disk. However I cannot find a
reasonable way to partition it with the part-add which
seems to want me to count sectors. All I want is
a 9G linux and a 2G swap.
Assuming the filesystem was in /tmp/root.tar.gz, the following code
will do this:
guestfish <<EOF
sparse /tmp/test.img 11G
run
part-init /dev/sda mbr
# 9GB sda1
part-add /dev/sda p 64 $(( 9*1024*1024*2 ))
# remainder in sda2
part-add /dev/sda p $(( 9*1024*1024*2 + 1 )) -64
mkfs ext4 /dev/sda1
mkswap /dev/sda2
mount /dev/sda1 /
tgz-in /tmp/root.tar.gz /
EOF
Example:
$ sh test.sh
$ virt-df -a test.img -h
Filesystem Size Used Available Use%
test.img:/dev/sda1 9.0G 276M 8.3G 4%
$ ll -h test.img
-rw-rw-r--. 1 rjones rjones 11G Apr 4 09:39 test.img
Whether this would actually boot is another question: you may also
need to add some grub commands to set up the bootloader, *or* (better
and easier IMHO) set up libvirt so that it boots from an external
kernel + initrd.
It also lacks access to rsync.
It's not the first time that someone has asked for rsync, and it
wouldn't be too hard to add. However note that rsync really gives you
no benefit when you're creating a filesystem from scratch, because
there's no original to rsync against. If you are updating a
filesystem image then rsync makes sense.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org
6:11 a.m.
New subject: [libvirt-users] Suggestions on building VM disks from scratch
On Wed, Apr 04, 2012 at 09:45:18AM +0100, Richard W.M. Jones wrote:
# 9GB sda1
part-add /dev/sda p 64 $(( 9*1024*1024*2 ))
# remainder in sda2
part-add /dev/sda p $(( 9*1024*1024*2 + 1 )) -64
This leaves the swap partition unaligned :-(
If you care about alignment (and you probably should) then this will
create properly aligned partitions:
part-add /dev/sda p 128 $(( 9*1024*1024*2 - 1 ))
part-add /dev/sda p $(( 9*1024*1024*2 )) -128
'Course the 'virt-alignment-scan' tool can be used to detect if your
partitions are aligned correctly. With the original image:
$ virt-alignment-scan -a test.img
/dev/sda1 32768 32K bad (alignment < 64K)
/dev/sda2 9663676928 512 bad (alignment < 4K)
With the correctly aligned image:
$ virt-alignment-scan -a test.img
/dev/sda1 65536 64K ok
/dev/sda2 9663676416 1048576K ok
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org
1:53 p.m.
New subject: Suggestions on building VM disks from scratch
On Wed, Apr 04, 2012 at 09:45:18AM +0100, Richard W.M. Jones wrote:
> Then I created my blank 'disk' file and tried to
> run virt-rescue on it. It crashed out with an
> error from febootstrap.
First of all, debug this properly:
=====================================================================
(1) What is the full error message?
I upgraded and installed a few more things and my error at least
changed, at least so I thought:
# virt-rescue -a recovery2.immortaldata.net.raw
mke2fs: Attempt to write block to filesystem resulted in short write while zeroing block
1048560 at end of filesystem
Could not write 6 blocks in inode table starting at 917506: Attempt to write block to
filesystem resulted in short write
febootstrap-supermin-helper: /sbin/mke2fs -t ext2 -Fq
'/var/tmp/guestfs.cZge1g/root': failed
But guestfish apparently finds my small root disk to be a
tasty morsel of fish food and impolitely swallows it whole:
4.1G /var/tmp/guestfs.1PFF68
3.5G /var/tmp/guestfs.cZge1g
4.1G /var/tmp/guestfs.FYAm8O
4.1G /var/tmp/guestfs.JP2LNO
4.1G /var/tmp/guestfs.qsLaNA
4.1G /var/tmp/guestfs.wwKT58
4.1G /var/tmp/guestfs.ZueM9V
This maxed out the root partition. Once I found this was happening
I cleared this out and added:
TMPDIR=/home/tmp
This got me back to the original error message:
# virt-rescue -a recovery2.immortaldata.net.raw
febootstrap-supermin-helper: ext2: parent directory not found: /lib: File not found by
ext2_lookup
=====================================================================
(2) What is the complete, unedited output of
'libguestfs-test-tool'?
# libguestfs-test-tool
===== Test starts here =====
LIBGUESTFS_DEBUG=1
TMPDIR=(not set)
libguestfs: new guestfs handle 0x23dc190
library version: 1.14.8
guestfs_get_append: (null)
guestfs_get_attach_method: appliance
guestfs_get_autosync: 1
guestfs_get_direct: 0
guestfs_get_memsize: 500
guestfs_get_network: 0
guestfs_get_path: /usr/lib/guestfs
guestfs_get_pgroup: 0
guestfs_get_qemu: /usr/bin/kvm
guestfs_get_recovery_proc: 1
guestfs_get_selinux: 0
guestfs_get_smp: 1
guestfs_get_trace: 0
guestfs_get_verbose: 1
host_cpu: x86_64
Launching appliance, timeout set to 600 seconds.
libguestfs: [00000ms] febootstrap-supermin-helper --verbose -f checksum
'/usr/lib/guestfs/supermin.d' x86_64
supermin helper [00000ms] whitelist = (not specified), host_cpu = x86_64, kernel = (null),
initrd = (null), appliance = (null)
supermin helper [00000ms] inputs[0] = /usr/lib/guestfs/supermin.d
checking modpath /lib/modules/3.2.0-16-generic is a directory
picked vmlinuz-3.2.0-16-generic because modpath /lib/modules/3.2.0-16-generic exists
checking modpath /lib/modules/3.2.0-21-generic is a directory
picked vmlinuz-3.2.0-21-generic because modpath /lib/modules/3.2.0-21-generic exists
checking modpath /lib/modules/2.6.32-38-server is a directory
picked vmlinuz-2.6.32-38-server because modpath /lib/modules/2.6.32-38-server exists
supermin helper [00000ms] finished creating kernel
supermin helper [00098ms] visiting /usr/lib/guestfs/supermin.d
supermin helper [00098ms] visiting /usr/lib/guestfs/supermin.d/daemon.img
supermin helper [00098ms] visiting /usr/lib/guestfs/supermin.d/init.img
supermin helper [00098ms] adding kernel modules
supermin helper [00259ms] finished creating appliance
libguestfs: [00353ms] begin building supermin appliance
libguestfs: [00353ms] run febootstrap-supermin-helper
libguestfs: [00353ms] febootstrap-supermin-helper --verbose -f ext2
/usr/lib/guestfs/supermin.d x86_64 /var/tmp/guestfs.xtl6Jb/kernel
/var/tmp/guestfs.xtl6Jb/initrd /var/tmp/guestfs.xtl6Jb/root
supermin helper [00000ms] whitelist = (not specified), host_cpu = x86_64, kernel =
/var/tmp/guestfs.xtl6Jb/kernel, initrd = /var/tmp/guestfs.xtl6Jb/initrd, appliance =
/var/tmp/guestfs.xtl6Jb/root
supermin helper [00000ms] inputs[0] = /usr/lib/guestfs/supermin.d
checking modpath /lib/modules/3.2.0-16-generic is a directory
picked vmlinuz-3.2.0-16-generic because modpath /lib/modules/3.2.0-16-generic exists
checking modpath /lib/modules/3.2.0-21-generic is a directory
picked vmlinuz-3.2.0-21-generic because modpath /lib/modules/3.2.0-21-generic exists
checking modpath /lib/modules/2.6.32-38-server is a directory
picked vmlinuz-2.6.32-38-server because modpath /lib/modules/2.6.32-38-server exists
supermin helper [00000ms] finished creating kernel
supermin helper [02595ms] finished mke2fs
supermin helper [02596ms] visiting /usr/lib/guestfs/supermin.d
supermin helper [02596ms] visiting /usr/lib/guestfs/supermin.d/daemon.img
supermin helper [02601ms] visiting /usr/lib/guestfs/supermin.d/init.img
febootstrap-supermin-helper: ext2: parent directory not found: /lib: File not found by
ext2_lookup
libguestfs: error: external command failed, see earlier error messages
libguestfs-test-tool: failed to launch appliance
libguestfs: closing guestfs handle 0x23dc190 (state 0)
=====================================================================
(3) What version of libguestfs & febootstrap are using and where
did
you get them from?
Updated from official Ubuntu Precise Pangolin server last night.
Package: libguestfs0
Architecture: amd64
Source: libguestfs
Version: 1:1.14.8-1
Package: febootstrap
Architecture: amd64
Version: 3.12-1
Assuming the filesystem was in /tmp/root.tar.gz, the following code
will do this:
guestfish <<EOF
sparse /tmp/test.img 11G
run
part-init /dev/sda mbr
# 9GB sda1
part-add /dev/sda p 64 $(( 9*1024*1024*2 ))
# remainder in sda2
part-add /dev/sda p $(( 9*1024*1024*2 + 1 )) -64
mkfs ext4 /dev/sda1
mkswap /dev/sda2
mount /dev/sda1 /
tgz-in /tmp/root.tar.gz /
EOF
Example:
$ sh test.sh
$ virt-df -a test.img -h
Filesystem Size Used Available Use%
test.img:/dev/sda1 9.0G 276M 8.3G 4%
$ ll -h test.img
-rw-rw-r--. 1 rjones rjones 11G Apr 4 09:39 test.img
Whether this would actually boot is another question: you may also
need to add some grub commands to set up the bootloader, *or* (better
and easier IMHO) set up libvirt so that it boots from an external
kernel + initrd.
If I can get the grub installed it should, since the
original are in most cases virtual servers built on vmdk
disks on a licensed VMware ESX server.
The other way I found to get to this particular point was:
$ dd if=/dev/zero of=/recover2.us.net.raw count=20M
$ losetup /dev/loop0 recover2.us.net.raw
$ cfdisk /dev/loop0
create a 9G bootable linux partition and a 1G swap
$ kpartx -a -v /dev/loop0
$ mkfs.ext4 /dev/mapper/loop0p1 -m 0.01 -L "RecoverTest"
$ mkdir tmp
$ mount /dev/mapper/loop0p1 tmp
From the backup server:
$ cd <to the lastest dirvish backup set>
$ rsync -av tree/ root@rebuild.server.net:/srv/idcpool/tmp/
But I could not figure out a safe way to install grub that
would not put the boot disk of a critical server at risk
of getting its MBR clobbered. Grub is very good at doing
such things and very difficult to convince to do what *you*
want rather than what *it* wants.
I much prefer the technique of just using a guestfish script to
do it all as you showed, but I still need to load up the backup
set and install grub properly.
> It also lacks access to rsync.
It's not the first time that someone has asked for rsync, and it
wouldn't be too hard to add. However note that rsync really gives you
no benefit when you're creating a filesystem from scratch, because
there's no original to rsync against. If you are updating a
filesystem image then rsync makes sense.
Actually, what the situation is that for our restoration
of *last resort*, we have a server that does incremental
daily and for some key infrastructure 4 times daily backups
via dirvish. So what we need dirvish for is so that we
can connect to the backup server and copy the most recent
copy of the failed device.
So yes, we do have a good reason to use rsync as it gives
us a very simple secure data transfer of the files from
one server to the new image.
The alternative is to do the rsync over to the rebuild
server, being careful not to get links messed up, tar.gz
the result and then pray the result will actually recreate
things, links, dev files, uid.gid's, modes, etc on when
unpacked. I have an inherent distrust of adding extra
steps into things if I can avoid them, particularly
when discussing a mission critical last resort failsafe.
Oh, and yes, we do separately back up database files via
the appropriate snapshotting and those would have to
be overloaded seperately after the main restoration.
That's one problem, the big one I am working on. The other
I can talk to you about after I get this one sorted, and
that is using virt-rescuse/guestfish in the virtualization
of an old SuSE server on end of life hardware. It of course
has lots of LVM's on the system disk just to make things
interesting...
3:09 p.m.
New subject: Suggestions on building VM disks from scratch
On Wed, Apr 04, 2012 at 07:53:26PM +0100, Dale Amon wrote:
On Wed, Apr 04, 2012 at 09:45:18AM +0100, Richard W.M. Jones wrote:
> > Then I created my blank 'disk' file and tried to
> > run virt-rescue on it. It crashed out with an
> > error from febootstrap.
>
> First of all, debug this properly:
=====================================================================
> (1) What is the full error message?
[...]
# virt-rescue -a recovery2.immortaldata.net.raw
febootstrap-supermin-helper: ext2: parent directory not found: /lib: File not found by
ext2_lookup
This is because you need to run:
sudo update-guestfs-appliance
=====================================================================
> (3) What version of libguestfs & febootstrap are using and where did
> you get them from?
Updated from official Ubuntu Precise Pangolin server last night.
Package: libguestfs0
Architecture: amd64
Source: libguestfs
Version: 1:1.14.8-1
Package: febootstrap
Architecture: amd64
Version: 3.12-1
Unfortunately we found out today that Ubuntu 12.04's libguestfs
package is largely broken. For more information, see:
https://www.redhat.com/archives/libguestfs/2012-April/msg00028.html
There is no solution to the kernel bug that affects Ubuntu (only).
[...]
Bit busy now, but I'll have a look at the rest later.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 80 OCaml packages (the OPEN alternative to F#)
http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora
3:41 p.m.
New subject: Suggestions on building VM disks from scratch
[grub]
You can run grub from the guest (assuming it's a Linux guest), by
doing in guestfish:
sh "grub-install [other parameters]"
There are some provisos which you can read about here:
http://libguestfs.org/guestfs.3.html#running_commands
We also provide a grub-install command which runs the grub from the
host on the guest. This requires that the two versions match each
other, and it needs further development work to make a fully general
bootloader installer that would be secure and usable.
[rsync]
The issue with rsync is how to make it available from libguestfs.
rsync needs an 8 bit clean connection of some sort, usually an rsh or
ssh connection, and we could provide that.
However we are also trying to extend libguestfs to work remotely, and
then it becomes complex to route that connection from the client side
to the remote appliance (eg) over a libvirt connection.
Anyway if you want to add rsync, just add the package name to
appliance/packagelist.in and rebuild from source.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
2:10 p.m.
New subject: Suggestions on building VM disks from scratch
On Wed, Apr 04, 2012 at 09:09:03PM +0100, Richard W.M. Jones wrote:
Unfortunately we found out today that Ubuntu 12.04's libguestfs
package is largely broken. For more information, see:
https://www.redhat.com/archives/libguestfs/2012-April/msg00028.html
There is no solution to the kernel bug that affects Ubuntu (only).
Is this what you are talking about?
--------------------------------
root@kdev:/KdevArchive1/vmpool1# guestfish
Welcome to guestfish, the libguestfs filesystem interactive shell for
editing virtual machine filesystems.
Type: 'help' for help on commands
'man' to read the manual
'quit' to quit the shell
<fs> sparse /KdevArchive1/vmpool1/Mourne.sda 30G
<fs> run
warning: Unable to get device geometry for
/var/tmp/guestfs.7NJVau/root
febootstrap-supermin-helper: ext2: parent directory not found: /lib: File not found by
ext2_lookup
libguestfs: error: external command failed, see earlier error messages
<fs>
--------------------------------
2:16 p.m.
New subject: Suggestions on building VM disks from scratch
On Thu, Apr 05, 2012 at 08:10:59PM +0100, Dale Amon wrote:
On Wed, Apr 04, 2012 at 09:09:03PM +0100, Richard W.M. Jones wrote:
> Unfortunately we found out today that Ubuntu 12.04's libguestfs
> package is largely broken. For more information, see:
>
> https://www.redhat.com/archives/libguestfs/2012-April/msg00028.html
>
> There is no solution to the kernel bug that affects Ubuntu (only).
Is this what you are talking about?
--------------------------------
root@kdev:/KdevArchive1/vmpool1# guestfish
Welcome to guestfish, the libguestfs filesystem interactive shell for
editing virtual machine filesystems.
Type: 'help' for help on commands
'man' to read the manual
'quit' to quit the shell
><fs> sparse /KdevArchive1/vmpool1/Mourne.sda 30G
><fs> run
warning: Unable to get device geometry for /var/tmp/guestfs.7NJVau/root
febootstrap-supermin-helper: ext2: parent directory not found: /lib: File not found by
ext2_lookup
libguestfs: error: external command failed, see earlier error messages
No, this is because febootstrap in Ubuntu 12.04 is broken, which
prevents creation of the appliance. You have to build febootstrap (at
least 3.14) by hand, install it, and then rebuild the appliance by
hand (update-guestfs-appliance). This is explained in this email:
https://www.redhat.com/archives/libguestfs/2012-April/msg00028.html
We have no Ubuntu maintainer, so Ubuntu just pull in the Debian
packages which they don't test and they don't work well.
libguestfs works best (indeed, is commercially supported) on Fedora
and RHEL.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
New in Fedora 11: Fedora Windows cross-compiler. Compile Windows
programs, test, and build Windows installers. Over 70 libraries supprt'd
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4:14 p.m.
New subject: Suggestions on building VM disks from scratch
I've passed your info on to the Ubuntu-devel group
to see if anyone picks up on it.
3:57 a.m.
New subject: Suggestions on building VM disks from scratch
On Thu, Apr 05, 2012 at 10:14:06PM +0100, Dale Amon wrote:
I've passed your info on to the Ubuntu-devel group
to see if anyone picks up on it.
Thanks -- we do want it to work well on Ubuntu, and hillu is doing
a great job on Debian.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v
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