In this part I will discuss a possible solution to a problem I encountered several times already – failure to understand XenServer use of LVM, but first – a little explanation of the topic.

One of the worst things you can have in XenServer, is some wize-guy performing a ‘forget storage’ on a storage device still holding virtual disks related to VMs. As XenServer database is internal (for the whole pool) and not per-VM, all references to this virtual disks disappear, and you remain with bunch of VMs without disks, and later on, when the recovered from the shock and restored the SR, with a bunch of virtual disks you have no clue as to where they belong. Why?

I have had recently the pleasure and challenge of setting up VPN server for mobile devices on top of Linux. the common method to do so would be by using IPSec + L2TP, as these are to more common methods mobile devices allow, and it should work quite fine with other types of clients (although I did not test it) like Linux, Windows and Mac.
I have decided to use PSK (Pre Shared Key) due to its relative simplicity when handling multiple clients (compared to managing certificate per-device), and its relative simplicity of setup.

I find it that identifying a missing something in the fridge, and adding it to a list does not work well for me. It’s either that I take a mental note of the missing groceries, and then, almost immediately, forget them until the unpacking of the just-purchased groceries, back home, several days later, or that I actually move myself into writing it down on a note, placed on the fridge, and then, of course, forget to take the note with me to the supermarket. Not working.