Re: [ANNOUNCE] first stable release of OpenVZ kernel virtualizationsolution

[Philippe Pegon]

Hello,

By curiosity, what is the status for IPv6 in OpenVZ (I saw that it was 
in the roadmap on the website, but maybe you have more informations) ?

thanks
--
Philippe Pegon

Kirill Korotaev wrote:
> Hello,
>
> We are happy to announce the release of a stable version of the OpenVZ 
> software, located at http://openvz.org/.
>
> OpenVZ is a kernel virtualization solution which can be considered as a
> natural step in the OS kernel evolution: after multiuser and 
> multitasking functionality there comes an OpenVZ feature of having 
> multiple environments.
>
> Virtualization lets you divide a system into separate isolated
> execution environments (called VPSs - Virtual Private Servers). From the
> point of view of the VPS owner (root), it looks like a stand-alone 
> server. Each VPS has its own filesystem tree, process tree (starting 
> from init as in a real system) and so on. The  single-kernel approach 
> makes it possible to virtualize with very little overhead, if any.
>
> OpenVZ in-kernel modifications can be divided into several components:
>
> 1. Virtualization and isolation.
> Many Linux kernel subsystems are virtualized, so each VPS has its own:
> - process tree (featuring virtualized pids, so that the init pid is 1);
> - filesystems (including virtualized /proc and /sys);
> - network (virtual network device, its own ip addresses,
>   set of netfilter and routing rules);
> - devices (if needed, any VPS can be granted access to real devices
>   like network interfaces, serial ports, disk partitions, etc);
> - IPC objects.
>
> 2. Resource Management.
> This subsystem enables multiple VPSs to coexist, providing managed
> resource sharing and limiting.
> - User Beancounters is a set of per-VPS resource counters, limits,
>   and guarantees (kernel memory, network buffers, phys pages, etc.).
> - Fair CPU scheduler (SFQ with shares and hard limits).
> - Two-level disk quota (first-level: per-VPS quota;
>   second-level: ordinary user/group quota inside a VPS)
>
> Resource management is what makes OpenVZ different from other solutions
> of this kind (like Linux VServer or FreeBSD jails). There are a few
> resources that can be abused from inside a VPS (such as files, IPC
> objects, ...) leading to a DoS attack. User Beancounters prevent such
> abuses.
>
> As virtualization solution OpenVZ makes it possible to do the same 
> things for which people use UML, Xen, QEmu or VMware, but there are 
> differences:
> (a) there is no ability to run other operating systems
>     (although different Linux distros can happily coexist);
> (b) performance loss is negligible due to absense of any kind of
>     emulation;
> (c) resource utilization is much better.
>
> The last point needs to be elaborated on. OpenVZ allows to utilize
> system resources such as memory and disk space very efficiently, and
> because of that has better performance on memory-critical workloads.
> OpenVZ does not run separate kernels in each VPS and saves memory on
> kernel internal data. However, even bigger efficiency of OpenVZ comes
> from dynamic resource allocation.
>
> With other virtualization solutions, you need to specify in advance the
> amount of memory for each virtual machine and create a disk device and
> filesystem for it, and the possibilities to change settings later on the
> fly are very limited.
>
> The dynamic assignment of resources in OpenVZ can significantly improve 
> their utilization. For example, a x86_64 box (2.8 GHz Celeron D, 1GB 
> RAM) is capable to run 100 VPSs with a fairly high performance (VPSs 
> were serving http requests for 4.2Kb static pages at an overall rate of 
> more than 80,000 req/min). Each VPS (running CentOS 4 x86_64) had the 
> following set of processes:
>
> [root@ovz-x64 ~]# vzctl exec 1043 ps axf
>  PID TTY      STAT   TIME COMMAND
>    1 ?        Ss     0:00 init
> 11830 ?        Ss     0:00 syslogd -m 0
> 11897 ?        Ss     0:00 /usr/sbin/sshd
> 11943 ?        Ss     0:00 xinetd -stayalive -pidfile ...
> 12218 ?        Ss     0:00 sendmail: accepting connections
> 12265 ?        Ss     0:00 sendmail: Queue runner@01:00:00
> 13362 ?        Ss     0:00 /usr/sbin/httpd
> 13363 ?        S      0:00  \_ /usr/sbin/httpd
> 13364 ?        S      0:00  \_ /usr/sbin/httpd
> 13365 ?        S      0:00  \_ /usr/sbin/httpd
> 13366 ?        S      0:00  \_ /usr/sbin/httpd
> 13370 ?        S      0:00  \_ /usr/sbin/httpd   
> 13371 ?        S      0:00  \_ /usr/sbin/httpd
> 13372 ?        S      0:00  \_ /usr/sbin/httpd
> 13373 ?        S      0:00  \_ /usr/sbin/httpd
> 6416 ?        Rs     0:00 ps axf
>
> And the list of running VPSs:
>
> [root@ovz-x64 ~]# vzlist
>     VPSID      NPROC STATUS  IP_ADDR         HOSTNAME
>      1001         15 running 10.1.1.1        vps1001
>      1002         15 running 10.1.1.2        vps1002
>      [....skipped....]
>      1099         15 running 10.1.1.99       vps1099
>      1100         15 running 10.1.1.100      vps1100
>
> On the box with 4Gb of RAM one can expect 400 of such VPSs to run 
> without much troubles.
>
> More information is available at http://openvz.org/
>
> Thanks,
> OpenVZ team.
>
>
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