Xen: Workaround for VNC Mouse Pointer Problem with Linux PV VMs

The framebuffer driver for Xen has an annoying bug: If you want to connect to the console of your virtual machine using VNC, and you have the resolution set to something other than the default 800x600, then your mouse behaves strangely. The mouse position will be correct when the mouse is at the upper left corner of the virtual console. However, as the mouse moves from the upper left corner, the mouse quickly becomes misaligned. The problem is worse the greater the difference between your virtual display resolution, and the default 800x600 resolution.

Postfix: Manipulating the Mail Queue

The Postfix Mail Transfer Agent (MTA) is a widely used MTA, especially on Linux systems.  When testing, or doing maintenance on systems running postfix, you may need to see what messages are in the queue, and/or manipulate the queues.

To see messages in the mail queue, use the following command (this is the same as for sendmail):


To cause postfix to process the mail queue immediately:

postfix flush

To remove a specific message from the mail queue:

Linux: LVM snapshots of DRBD volumes

It is often convenient to use a Logical Volume (LVM2) as a DRBD backing device.  You then can use the DRBD device as usual, and create a filesystem on the DRBD device.  In addition to the many other benefits of LVM2, a DRBD device with an LVM backing device allows you to take snapshots of the device.  This article shows how to produce snapshots of these types of devices, and how to access your data.

Solaris: Configuring the Dump Device on VxVM Encapsulated Disks

If you use VERITAS Volume Manager (Symantec) to encapsulate the boot disk of a Solaris system, you may see messages like this on boot:

savecore: no dump device configured
dumpadm: no swap devices could be configured as the dump device

Normally on a Solaris system you would run the following command to correct this:

dumpadm -d swap

to indicate that you want to use the swap device as your dump device.  However, on a system with an encapsulated swap partition, you will see the following message from the above command: