Difference between OpenVZ and FreeVPS

 

Conclusion in the beginning

For those who have no time to read all subtleties of comparison, and we do not dare to doubt, that those are majority - we have decided to place a conclusion in the beginning to save time.

So,
you should choose FreeVPS if:

• You do not wish to be engaged in optimization of consumption of memory
• You wish to receive concrete quantity of RAM and SWAP, instead of mix of them
• You can be satisfied with CentOS 4.4
• You wish to operate installation and removal of packages through the control panel
• Wish to use OpenVPN, in standard network environment

you should choose OpenVZ if:

• You wish to squeeze out a maximum of each mbyte
• You need maximal reliability and isolation
• It is important for you to have a choice of Linux distros
• Know what is "OS tuning" and it is necessary for you to have maximal control over OS
• Want and can use OpenVPN, ports forwarding, etc. not with standard name of the interfaces

you should choose a virtual hosting if:

• You do not have experience in sites and the Internet projects arrangement
• It is not necessary to you the control over each element of system
• You wish to operate resources through the convenient control panel
• Your project does not demand significant system resources and non-standard components
• You want as much as possible budgetary solution

Characteristics of virtualization patch OpenVZ

First stable release OpenVZ have been announced 5th December, 2005. OpenVZ is an Operating System
-level server virtualization solution, built on Linux. OpenVZ creates isolated, secure virtual environments VEs (otherwise known as virtual private servers, or VPSs) on a single physical server enabling better server utilization and ensuring that applications do not conflict. Each VE performs and executes exactly like a stand-alone server; VEs can be rebooted independently and have root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files.
Any software can work inside VPS without any specific changes or fine tunings.
User can change configuration files and install additional software.
Virtual private servers are completely isolated from each other (file system, processes, inter-processes communication (IPC), sysctl variables).
The processes which belong to a virtual server are spread on all accessible processors of system hence VPS is not bind to only one processor and can use all accessible CPU capacity.
Every VPS includes own IP address.
Network traffic of virtual server is completely isolated from other virtual servers. In other words virtual server are protected from each other such way, that listening of the another's traffic is not possible.
Inside VPS it is possible to use firewall rules, by means of iptables to limit access to various services.
Manipulations with tables of routings and expanded function managements of routing are accessible to every VPS too.
For example, it is possible to change MTU for various directions, to specify various addresses and sources for various directions and so on.
Allows to guarantee quality of service (QoS) due to high-quality priority processor time and disk input-output.
This patch supported by greater group of developers financed by commercial organization SWSoft that enables a patch to develop dynamically, considering enterprise requirements and support of business customers.
At present FreeVPS, though too is financed development, cannot brag of greater staff of programmers, fast development and instant correction of mistakes.
Also due to ideology of OpenVZ - it is possible to install virtually any Linux distro to the VE and that is significant difference from technology FreeVPS which, as a matter of fact, is strongly adhered to OS, installed on node.

One more difference is realization of virtualized devices in OpenVZ, in particular it concerns network interfaces, not going deep into details, difference from a usual server and FreeVPS VEs consists that on a host-server the special virtual device (venet0), to which network interfaces with same not absolutely habitual name are attached is created.
It does not create special inconveniences, or any non-standard situations.
Last radical distinction is the manager of memory and a principle of its work.
At present OpenVZ is not able to separate and does not give an opportunity to operate distribution of memory pages allocated for virtual servers, between real memory and virtual (SWAP).

Also the memory accounting occurs on volume of the requested memory by means of malloc ()/calloc () and similar functions calls, instead of really used memory at present time.

That is:

 #include <stdio.h>
 #include <stdlib.h>
 
 int main()
 {
         size_t len = 40L * 1024 * 1024;
         void *p = malloc(len);
         if (!p) {
                 perror("malloc");
                 exit(1);
         }
         free(p);
         printf("Success\n");
         return (0);
 }
 

Will allocate the certain portion of memory, but it will not be used.

А

 #include <stdio.h>
 #include <stdlib.h>
 
 int main()
 {
         size_t len = 40L * 1024 * 1024;
         void *p = malloc(len);
         if (!p) {
                 perror("malloc");
                 exit(1);
         }
         memset(p, 0, len); /* Difference in this line, 
                               this function fills the allocated site with data.*/
         free(p);
         printf("Success\n");
         return (0);
 }
 

Will allocate and will use.

In case of OpenVZ - memory accounting occurs by quantity of the "requested" memory (the first example),
in case of FreeVPS - on really used (the second example).


Strong feature OpenVZ is well worked mechanism of turns and privileges CPU and disk IO.

Characteristics of virtualization patch FreeVPS.

Project FreeVPS has started earlier than OpenVZ, the provisional beginning of public releases of a patch is addressed by the beginning of 2004.
All that concerns to advantages OpenVZ as a whole, as representative of the os-level virtualization solution, such as: security and separation of one virtual environment from another, the maximal utilization of server physical resources and good scalability in the same degree concerns and to FreeVPS, basic differences FreeVPS is:

• Per context IPsec (IP Security protocols).
• Possibility to create inside VPS virtual network interfaces or virtual network interface aliases (up to 16*16 = 256).
• Virtual network interfaces outgoing bandwidth limitation ability
• Separated disk name-space to extend VPS <=> host and VPS <=> VPS security and functionality
• Per context total, separate virtual memory and SWAP accounting.

As it has been told above, in the paragraph devoted OpenVZ, difference of these patches consists in a way of the memory accounting, in OpenVZ - the account of memory occurs by quantity of the "requested" memory (see the first example above), in case of FreeVPS - on really used (see the second example above).

Also FreeVPS tries to mark memory of the loaded libraries of applications as the general, reducing the considered volume of memory used by a virtual server more actively.
That enables, in difference from OpenVZ, on the minimal tariff plan to start LAMP (Linux + Apache + MySQL + PHP) system, having put to it average control panel without any additional adjustment or tuning of the specified applications and operational system as a whole.

Possible lack which follows from more aggressive approach to a designation of memory, the general is greater attachment to the Linux distribution (namely to system libraries) host system which in practice from reasons of solutuion reliability does not allow to install different Linux distros on virtual servers.