An important feature of your Freedom server is your virtual disk. Your virtual disk contains the operating system that your virtual server runs on as well as your files and other data. It behaves just like a physical disk drive and it belongs to you, and you alone. Other virtual servers on the physical machine that hosts your server do not have access to your virtual disk.
The size of your virtual disk depends on the specific Freedom server that you purchased. You can check to see how much free space is left on your virtual disk at any time through the VAdmin Web interface or by using the df command from the command line.
The df command returns a report on three important filesystems that are available to your server - the first of which is your virtual disk. By default, the information is displayed in 1 kilobyte blocks, but df can be made to display a more intuitive report when run with the -h flag, which stands for human readable.
Here is some sample output from df -h, as run on a virtual server with was ordered with a 500MB virtual disk:
Filesystem Size Used Avail Capacity Mounted on
/dev/vnx 583M 34M 503M 6% /virtual/home/ip.add.re.ss
The first column, /dev/vnx, is the device name of your virtual disk. The x will be replaced with an number between 5 and 254 depending on the number assigned to your virtual server by the physical machine which hosts it.
The second column indicates the size of the virtual disk, the third column shows how much of the disk space has been used, and the fourth column shows how much of the disk space is still available to be used.
You may be wondering why the size is reported as 583 MB in this example of a 500MB virtual disk. The reason is that, as an added value to our customers, we adjust the size of the virtual disk at the time you order it to take into consideration the amount of space required by your operating system and preinstalled applications. When you receive your server, you receive at least that amount as available disk space.
You may also be wondering why, if the total virtual disk size in this example is 583 MB and only 34 MB are in use, why only 503 MB show as being available. This is because in UNIX, a small percentage of a disk drive is kept in reserve and hidden from users to maintain optimal performance and for use in case of an emergency. The extra space is actually there; it is just kept hidden from the system. We’ve again compensated for this as another added value for our customers and adjust the size of the virtual disk to provide you with maximum value. Once the disk has reached 100% capacity, only the superuser and system programs may use this remaining hidden space.
The fifth column displays how much of the disk has been used as a percentage. Note that because the system keeps a portion of the space in reserve, it is possible to see a disk that is over 100% capacity. However, having a disk go above 100% capacity is not recommended, and can prevent your server applications from functioning properly. You should always keep your disk capacity below 100% if at all possible by clearing unnecessary files or increasing the size of your virtual disk.
The last column displays where the virtual disk is mounted on the physical machine that hosts your virtual server. This information is of little use to you and is unimportant.
As mentioned previously, your virtual disk is only one of three filesystems that are displayed in the report that df generates. Let’s talk quickly about the other two. If you’ve ever installed an operating system on a PC, you may be asking yourself the following question: How can my Freedom server contain an entire operating system, plus the files required for the more than 50+ preinstalled applications it provides, and be using up less than 35 MB of space on my virtual disk? It’s a good question, because to install all of this would require more than 600 MB of space. So how do we do it? Through a trick that we like to call 3FS – Freedom Flexible Filesharing. 3FS allows us to install many of the files belonging to the operating system and preinstalled applications into a location that makes them available to all the Freedom servers on the physical machine in a read-only mode. We then install references to these files, called symbolic links, in your virtual disk in place of the actual files themselves. The result is a flexible, secure environment where disk space is conserved, installation is fast, and administration is made easier; hence the name, Freedom Flexible Filesharing.
The key to 3FS is the second filesystem displayed in the report returned by the df command. This filesystem is /usr/virtual/share, more commonly referred to as “the share”:
127.0.0.1:/usr/virtual/share 2.8G 1.5G 1.1G 56% /virtual/home/216.122.xx.x/usr/virtual/share
You cannot store files in /usr/virtual/share, but you can access its contents. The files in /usr/virtual/share do not take up space on your virtual disk. More information about this special filesystem is available in the section entitled “3FS - Freedom Flexible Filesharing” in the “Advanced Topics” section of this guide.
The third and final filesystem is the process filesystem. The programs that run on your virtual server use this special filesystem to keep track of what they are doing. In general, you should never need to access this area directly, and unless you know specifically what you are doing, it’s a good idea not to try. In the report returned by the df command, the process filesystem appears like the example below:
procfs 4.0K 4.0K 0B 100% /virtual/home/216.122.xx.x/proc
If it ever becomes necessary for your Freedom server to be moved to a different physical machine, your virtual disk is simply unmounted from its current location, moved to the new machine, and remounted there. Your virtual disk is a vital part of the security and convenience provided to you by your Freedom server.