Gordon Turner » linux

Migrating from Xen-Fedora to KVM-Ubuntu

Gordo — Thu, 28 Jan 2010 16:46:59 +0000

Recently I completed my migration from Xen / Fedora Core to KVM / Ubuntu. I have been a long time Redhat user, but I felt that Fedora was no longer stable enough for me. I was tempted to move to CENTOS but it didn’t feel right, not quite an ‘official’ Redhat release. So I decided on Ubuntu with KVM virtualization.

The transition was reasonably painless, a few adjustments to make, like using init.d instead of service. I made some notes for myself that others might find helpful:

Ubuntu Notes

Ubuntu KVM Host notes

Ubuntu KVM Guest notes

Howto: Xen+LVM guest OS to VMWare guest conversion

Gordo — Sun, 19 Aug 2007 19:03:10 +0000

I have several virtual machines (including this webserver) hosted on a Xen Linux host. I wanted to be able to use the same linux configuration in my VMWare player on my desktop for testing.

Here are the rough steps that I went through to convert a linux guest that was on a LVM partition to a raw file on my Windows Desktop that the VMWare player could use.

Software: Redhat Fedora Core 6, Xen, LVM, VMWare Player 2.0.0

1. The Xen guest is a running a paravirtualized kernel, hopefully I will upgrade the cpu soon. So, if you are running a Xen specific kernel like I am, you must install the regular, non-paravirutalized kernel. Login as root onto the guest and run: [root@xen-guest ~]# yum install kernel.i686

2. Restart the guest and confirm that the new kernel is in the grub startup menu and that the default kernel is still the paravirtualized kernel (don’t want to mess up the existing system). Once confirmed, halt the guest.

3. Map the LVM partition. As root on the Xen Host type:

[root@xen-host ~]# kpartx -av /dev/VolGroup00/ImageData00 add map ImageData00p1 : 0 6281352 linear /dev/VolGroup00/ImageData00 63

(I have always done the mapping, I am not sure if this is required.)

4. Using dd, copy the partition to an image file. As root on the Xen Host type:

[root@xen-host ~]# dd if=/dev/VolGroup00/ImageData00 of=/some/path/ImageData00.img bs=512 6291456+0 records in 6291456+0 records out 3221225472 bytes (3.2 GB) copied, 276.703 seconds, 11.6 MB/s

This step will take a while, the of should be somewhere with lots of space.

Note: copy down the number of records in/out, this is needed later.

5. Unmap the LVM partition. As root on the Xen Host type:

[root@xen ~]# kpartx -dv /dev/VolGroup00/ImageData00 del devmap : ImageData00p1

6. Run fdisk on the image file to get the disk geometery. As root on the Xen Host type:

[root@xen FileBackedHosts]# fdisk /dev/VolGroup00/ImageData00


Command (m for help): p
Disk /dev/VolGroup00/ImageData00: 3221 MB, 3221225472 bytes
255 heads, 63 sectors/track, 391 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System /dev/VolGroup00/ImageData00p1 * 1 391 3140676 83 Linux

Note: copy down the head, sectors/track and cylinders values.

7. Copy the image file to the Windows desktop, I used pscp to move it over.

8. Grab a copy of an empty VMWare virtual machine (here is mine). Edit the *.vmdk file to:

version=1 CID=e37454cd parentCID=ffffffff createType="monolithicFlat"


# Extent description
RW 6281352 FLAT "ImageData00.img" 0
# The Disk Data Base 
#DDB

ddb.adapterType = "ide" ddb.geometry.sectors = "63" ddb.geometry.heads = "255" ddb.geometry.cylinders = "391" ddb.virtualHWVersion = "3" ddb.toolsVersion = "0"

Replace your sectors, heads and cylinders with your values from earlier. Replace “6281352″ with your records in/out number.

9. Start the VMWare image. On first boot, choose the regular kernel in the grub startup menu, edit it to remove the “console=…” and add “single” to boot into single user mode.

10. Once booted in single user mode, edit the /etc/inittab to comment out “co:2345:respawn…” and uncomment other “1:2345:respawn…” consoles. Reboot and choose the regular kernel again.

11. Once booted, edit the /boot/grub/grub.conf and change “default=1″ to “default=0″, this should be the regular kernel. From now on, the regular kernel should boot with no problems.

Howto setup Sendmail to use ISP SMTP server

Gordo — Tue, 16 Jan 2007 12:18:46 +0000

Warning, Geek alert.

In order for the WordPress emails to go out properly, I had to setup Sendmail to connect to my Internet Service Providers SMTP server.

More details after the cut.

For most hosted providers, Sendmail is automatically configured. However, if yo are hosting your server on a private machine at home like I am, with no mail server, you have to use your ISP to send mail.

Here are the instructions on how to do this on Fedora Core 6, with thanks to Dave Pavao.

- All of these steps are done as root. - Install sendmail-cf:

yum install sendmail-cf

- Edit the sendmail.cf file:

vi /etc/mail/sendmail.mc
...
define(`SMART_HOST', `smtp-rog.mail.yahoo.com')dnl
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
FEATURE(`authinfo',`hash /etc/mail/isp-info')dnl
...

- Edit the rogers-info file, here juser and password are your credentials provided by Rogers:

vi /etc/mail/isp-info
AuthInfo:smtp-rog.mail.yahoo.com "U:juser@rogers.com" "I:juser@rogers.com" "P:password"

- Run make:

cd /etc/mail
make

- Create the isp-info.db file:

makemap hash /etc/mail/isp-info < /etc/mail/isp-info

- Restart sendmail:

service sendmail restart

That should be it, this will make it into my wiki eventually.

GT.