Installing Win7 guest on KVM with CentOS 7

Installation with virt-manager is fairly straightforward. However, unfortunately, this results in a guest that uses the very slow IDE disk driver. Changing to use virtio is a little tricky - this blog post was very helpful: http://setdosa.blogspot.com/2013/09/moving-your-windows-guest-from-ide-to.html

This is a general handy guide: 
https://support.opennodecloud.com/wiki/doku.php?id=usrdoc:os:win-guest

Installing Win7 guest in Virtualbox from a USB stick image

1. Use dd to make an image file of the entire stick - e.g. dd if=/dev/sdg of=usb_stick.img
2. Copy to target machine.
3. Convert to .vmdk file using: "VBoxManage internalcommands createrawvmdk -filename output_usb.vmdk -rawdisk usb_stick.img (thanks to: http://www.dallagnese.fr/en/computers-it/boot-on-your-usb-drive-in-virtualbox-4/ ).
4. Add the image file to the SATA controller as a hard drive. Make sure it has lowest SATA port number.

SSH via intermediate host

In terminal on local machine:

$ ssh -f -N -L6969:localhost:6969 intermeduser@intermedhost
$ ssh intermeduser@intermed
intermedhost$  ssh -f -N -L6969:localhost:22 destuser@desthost

Then, in other local terminals:

$ ssh -p 6969 destuser@localhost

Updating Seagate Barracuda 7200.11 drive firmware on a Dell Optiplex 960

This was a real head-scratcher, because Seagate's ISO image would NOT boot on this machine, whether burnt to a CD or written to a flash drive with unetbootin.

I eventually succeeded by extracting the El Torito floppy image from the ISO using http://freecode.com/projects/geteltorito and then putting the files on a FreeDOS bootable flash drive using unetbootin.

I also found that unetbootin/FreeDOS requires a FAT16 formatted primary partition on the flash drive to work properly.

Obscure xinetd tip

If you have a "wait=yes" server bound to 127.0.0.1, you can get a syslog full of messages like this:

xinetd[25741]: warning: can't get client address: Transport endpoint is not connected

The trick is to add "flags=NOLIBWRAP".

THis bug report gives a clue as to the underlying cause: https://bugzilla.redhat.com/show_bug.cgi?id=108583

Migrating a guest VM with Xen 3.2

'xen migrate' didn't work - it hung, as others have reported.

It turned out to be as simple as:

1. Stop the original guest.
2. Copy the disk image and the config files ( in /etc/xen/vm) to the new host.
3. Execute 'xm create guest-name' on the new host.
4. Done!

Expanding a Xen image disk

I found various pages on this, but the instructions weren't quite accurate for openSUSE 11.0

1. Stop the guest.
2. Find the image file with 'losetup -a'
3. Make a backup copy.
4. Add (e.g. 4Gbyte) with:  dd if=/dev/zero bs=1024k count=4096 >> /xen/images/yourguest/disk0
5. Mount with: xm block-attach 0 'file:/xen/images/yourguest/disk0' /dev/xvda
6. Using fdisk, find the partition, and resize it.
7. Use resize2fs to increase the filesystem to fill the space, run fsck -f to verify.
8. Unmount with: xm block-detach 0 /dev/xvda
9: Restart the guest.