I have been implementing Nas4Free recently, and found this system to be a very nice one. I might try to port its web interface to Linux, as it completes a set of requirements (regarding graphic interface) I do not find in Linux, and wish I could…
However, I have had to add a driver for ConnectX 10GbE interface, which, unfortunately, was not included.
This might show as a simple task, however, for a person unfamiliar with FreeBSD, it was a challenge.
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.
ndmpcopy is a wonderful command. It allows a fine-grained copy of files or directories between NetApp devices, across network, even if they do not use (or unlicensed) SnapMirror, SnapVault and the rest of the Snap* products NetApp offer.
In this example I will show how to copy a LUN from one filer to the other.
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 a single node of a pool using a different license server. Temporary, unfortunately. It has expired, and as the purchase process was somewhat prolonged, I have had to extend it. I did not want to disconnect my other-four-hosts-pool from the permanent license server, which works so fine for the last year or so, so I have had to change the license only for a single host.
XenServer 6.1 XenCenter does not allow changing the license server for a single host in a licensed pool. I have had to search for a solution. The solution looks like this:
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.
Using the GUI, it could be somewhat complex identifying a VM based on its MAC address. There are several solutions on the network using PowerShell, but I will demonstrate it using a simple bash script, below. Save, make executable, and run.
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.
The concept of running a virtual machine, KVM-based, in this case, under RHCS is acceptable and reasonable. The interesting part is that the directive replaces the directive and acts as a high-level directive for VMs. This allows for things which cannot be performed with regular 'service', such as live migration. There are probably more, but this is not the current issue.
In my post here, I have explained (actually – created a shell script) to map USB disks to VMs directly. While this is easy and simple, it becomes more challenging when you want to map internal SATA disks. They are not attached to the “Removable Storage” SR, and thus, behave differently.