azouhrXen or KVM
Since little more than half a year, I am in the process of installing a new virtualization Platform. One of the hardest decisions to make was if we should use Xen or go with KVM. We already have Xen in production and I know that it works well. From KVM we expect, that it will be growing faster then Xen and be the right thing on the long run.
The machines that I have as hosts are quite powerful. They are 48 Core AMD Opteron with 256 GByte of memory, and FCoE based Storage devices for the guests. We are using a converged network where both, FC and Ethernet, go over the same redundant 10GBit ethernet line. Storage is external FC storage from different devices.
The most important features that we need for such a platform are these:
- Stability
- Performance
- Tools
After doing a number of tests, it is obvious that both systems are stable. I did not encounter crashes related to the hypervisor technology.
Performance is also an interesting point. Especially the speed of block and network devices is not the best when using virtualized guests. This holds true for both, KVM and Xen. Note, that comparing CPU or Memory performance in standard environments is not very useful. Even if one of the systems performs slightly better, both are very close to hardware speed in terms of CPU and Memory. However outbound connectivity is an issue for both.
One exception is when you invest some more effort and use the new NUMA features provided with the latest Xen. The IO performance of network devices was roughly 4 times the performance without using NUMA.
One of the drawbacks when using NUMA on Xen is, that you have to use the tool “xl” instead of “xm”. For some unknown reason, you can dump configurations from “xl” only in SXP format, but “xl” won’t let you start a guest from such a configuration. This renders the tool quite useless in a production environment.
This brings me to Tools. For me, Xen has the tools that are easier to operate than KVM. Especially life migration syntax is way easier on Xen. On the other hand, both are simple enough to be operated by experienced people. For those that do not like the command line, “libvirt” offers a number of graphical tools that can cope with both, Xen and KVM.
One thing to mention is, that with Xen you can enable a locking mechanism that prevents you from running the same guest on different Hosts. I have yet to find similar functionality on KVM.
Now let me add some words about issues I encountered. As I already told, we have Xen running productive and it works quite well. I also found the Xen developers being relatively responsive when some bug occurs. From my other blog entries you can see, that Xen also offers a number of debugging capabilities.
With KVM, there are two major issues I have right now
- Life migrations are not safe in KVM. I repeatedly encountered block device corruptions when doing life migrations. This also holds true when using “cache=none” for the qemu configuration. Simple migrations still work without problems.
- The networking inside a 10GBit environment behaves strangely. When connecting a Guest to a remote server I get connection speeds at about 30-40kByte/s. All the connections between the respective hobs in this environment work as expected (Guest -> Host, Host -> Server).
Resume:
Both, KVM and Xen are usable if you do not need life migrations. OTOH life migration is an essential feature in a production environment. It enables you to service a Host without taking down the guests. If the life migration feature is not fixed until SLES11-SP2, I will have to return to Xen.
For the moment, KVM is not on par with Xen. However, in the long run I expect that KVM will gain momentum and eventually be the platform of choice. If I had to select a platform in a critical business environment today, I would go with Xen. On the long run, it might be better to go with KVM, but this depends on the further development of KVM.
The major development areas that will influence my decisions in future will be
- IO Speed
- Support of NUMA architectures
- Support for HA features like “Remus” or “Kemari”
The race is still open…
My openSUSE 12 Journal - 4: Minor Frustrations
Boot 12.1 using the old System V init
In my first journal entry, I complained the lack of "chattiness" during boot since the adoption of Systemd. You can easily switch to the old System V init on boot. At the grub boot loader screen (usual 8 seconds delay) and before you hit Enter to boot, press the F5 button to switch from default to System V. Now, press Enter to boot and press the Esc key during the splash screen to see the familiar System V init messages.
init=/sbin/sysvinit
For example, in /boot/grub/menu.lst, at the end of the line starting with "kernel /boot/vmlinuz-3.1.0-1.2-desktop...", append the line above and save the file. On the next boot, you can verify the change in the Boot Options field. Press Enter and you will boot up 12.1 under the old System V init.
Read more »
Air Video Server on openSUSE 12.1
Since the Air Video Server is written in Java and uses a customized version of FFMPEG, it would be possible to run it on Linux. The folks behind Air Video though supportive but are NOT offering official support for Linux.
I have been successful in making Air Video Server (AVS) work on openSUSE 11.3, 11.4 and 12.1. Here are the steps:
Read more »
MemberopenSUSE election platform 2011
Yep, I'm running for the privilege of being on the openSUSE board again. Lots of fine candidates this time, which is pretty cool in its own right.
I finally managed to fill out the remaining bits of my election platform page, so if you're interested, please have a read -- yes, I know, it's long ;)
The short summary:
- I care about the contributors, their environment, it must be a fun place where people feel comfortable, with friends
- I care a lot about the people aspects of the project, probably even more so than for the technical bits
- I believe that I have a few ideas on concrete things we (and specifically, but not only, the board) should get involved in
All that "I, I, I" comes quite tedious, to be honest, and I'm under the impression that I'm bragging around, which is something my inner beast is spanking me for, endlessly. But well, the whole purpose is specifically to explain what each candidate proposes so I guess it's fine.
So if you adhere to what I wrote there and/or if you trust me to do the right things, do vote for me -- don't think that oh well, I'll be elected anyway, if everybody thinks like that, I won't ;D
openSUSE ARM gains a new Sponsor
A dot in the map
Today though it's different, I am taking a break from a presentation it was supposed to be ready...Well...Yesterday, but I am still looking for the right kittens photos to complete this presentation(...don't ask...). Anyway normally I would just watch a movie or something but I am a bit in a mood to blog and latelly I had too much on my plate and had no time to do it, so here I am.
Anyway a friend of mine, Efstathios Chatzikyriakidis had this briliant and simple idea, to make a map where people around the world would state their possition in the map and the OS they use. Some of you might find this useless but I find interesting the fact that I could see the preferance of people around me on what Open Source or Free Software they use and some of you might too. The site is called OSHACKERS and it is licenced under the GNU GPLv3 and if you are curious I would suggest to give it a look and why no register...
Join The G(r)EEKOS Release Parties!!!
The openSUSE 12.1 distribution is released. After 8 months of hard work by the openSUSE community, the result could be something less than awesome. It is true that openSUSE 12.1 has received the best reviews of all famous open source sites and also has begun to gain many new members at the community, users and contributors.
Time to celebrate!
As is known the openSUSE community after the hard work done to release another great distribution, wants to celebrate it! And why not! Around the world communities, Linux groups and LUGs organize release parties.
The G(r)eekos Way!!!
openSUSE 12.1 is already installed on our machines by November 16. The Greek openSUSE community in collaboration with other communities, university Linux teams and LUGs invites you to come and celebrate the brand new release of openSUSE 12.1. Release parties are organized in many Greek cities! If you're near a city where a party is organized do not hesitate to meet us, attend an Install Fest or a presentation about openSUSE 12.1, drink lots of beers, talk with us and have fun!
We expect to meet you at one of the parties, as well as help you organize one in your town! Good company, beer and goodwill are the key ingredients of a successful Release party!
On Thursday 1 December we will celebrate in Larisa with a presentation and an Install Fest at 13:00 and afterward we will go at a local tsipouradiko. Moreover, on Saturday 3 December in Kastoria at 19:00 at Zaza bar. Furthermore, on Sunday 4 December we will celebrate in Thesaloniki at Bar Pierrot Le Fou at 22:00. Last but not least there will be 3 more parties that are going to be announcend the next few days.
Have a lot of fun!
On the road again: MYGOSSCON 2011
The title of my paper is "Key Trends: Challenges, Opportunities and Leverage for Linux/OSS Ecosystem". I look forward to the discussions it will generate. :)
Personally, I am looking forward to this with excitement as I have been granted the latitude in content creation. I will be approaching the topic from another angle and with, what I hope to be, a fresh perspective.
SOCKS proxy over SSH
SOCKS is an Internet protocol that routes network packets between a client and server through a proxy server. -- via WikipediaI'm certain as most, if not all, of our daily applications implement themselves some way of proxying (mostly HTTP, HTTPS and SOCKS) or use the system-wide configured network proxy server. Now all we need is a remote and secure server to proxy and tunnel. This is the part where SSH enters:
Secure Shell (SSH) is a network protocol for secure data communication, remote shell services or command execution and other secure network services between two networked computers that it connects via a secure channel over an insecure network: a server and a client (running SSH server and SSH client programs, respectively). -- via Wikipedia
-D [bind_address:]portSpecifies a local ``dynamic'' application-level port forwarding. This works by allocat-ing a socket to listen to port on the local side, optionally bound to the specifiedbind_address. Whenever a connection is made to this port, the connection is forwardedover the secure channel, and the application protocol is then used to determine where toconnect to from the remote machine. Currently the SOCKS4 and SOCKS5 protocols are sup-ported, and ssh will act as a SOCKS server. Only root can forward privileged ports.Dynamic port forwardings can also be specified in the configuration file.
I will not provide the details of what each option features - run 'man ssh' and find by yourself. The result is a SOCKS proxy over SSH. Now let's wrap it in a bash script:ssh -C2qTnN -D <PORT> <USER>@<IP>
#!/bin/bash
if [[ `uname` == 'Darwin' ]]; then
trap " {
echo \"Setting SOCKS proxy down...\" ; \
networksetup -setsocksfirewallproxystate ethernet off ;
networksetup -setsocksfirewallproxystate wi-fi off;
exit 1;
}" ERR INT TERM EXIT
networksetup -setsocksfirewallproxystate ethernet on
networksetup -setsocksfirewallproxystate wi-fi on
fi
ssh -C2qTnN -D 9999 <USER>@<IP>
Greek openSUSE community, Translation of openSUSE Weekly news in Greek (issue 202)
Hello everyone!
I am very pleased to announce the new issue (202) of openSUSE Weekly News in Greek.
In this issue you will read about:
* openSUSE 12.1: All Green!
* The Register/Iain Thomson: New openSUSE heads for cloud, virtual markets
* h-online/Chris von Eitzen: openSUSE 12.1 arrives with systemd and Btrfs
* Join or organize openSUSE 12.1 Launch parties!
* openSUSE participates in Google Code-in
As well as many interesting news about openSUSE and useful advice, which can make our lives easier.
Enough said though... Read more at: http://own.opensuse.gr, http://el.opensuse.org/Weekly_news or www.os-el.gr
We are always looking forward to receiving your comments as well as suggestions regarding things you would like to read about in our next issue.
The openSUSE Weekly News is being translated in the Greek language from issue #150. You can read older translated issues here: http://el.opensuse.org/Κατηγορία:Weekly_news_issues
Enjoy it!
Efstathios Agrapidis (efagra)