Hi List, Being very new to Xen I have a few generic questions for the list, I hope to grab some useful advice and pointers to documentation. I am evaluating Xen to consolidate a few existing servers into one appliance (mainly in order to reduce power consumption, heat, and hardware failure risks). I plan to have a SER router, an Asterisk LCR router, a voicemail server, a calling card server and maybe even a MySQL server, all in one box. In order to do this, I have ordered a dell poweredge 1850 bi-xeon, 4 gb ecc ram, and raid 1 SCSI disks. It also has dual power supplies and dual port network cards. The idea is to have redundancy wherever possible in order to lower the risk of server downtime. I would like to know if there is a "getting started" howto somewhere I could play with on a test server before my production server comes in. Also I would like to know if there are known issues with the hardware I have ordered. I plan to use debian sarge for the host and all the virtual servers, does it sound like a reasonable choice for Xen? Is it possible to "migrate" a virtual machine to a completely different PC (with different hardware specs)? That would be a very useful feature to have for upgradability. Finally, are there consultants available for remote training and support? It would be handy to have someone who can help while I go through the process of getting Xen to work. Best Regards, Jean-Michel. -- Jean-Michel Hiver - http://ykoz.net/ Découvrez la Réunion des Technologies IP & Telecom TEL: +262 (0)262 55 03 98 - RCS 434 273 330 SAINT PIERRE _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
>Message: 2 >Date: Fri, 27 Jan 2006 18:00:48 +0400 >From: Jean-Michel Hiver <jhiver@ykoz.net> >Subject: [Xen-users] Getting started with Xen >To: xen-users@lists.xensource.com >Message-ID: <43DA2790.2010002@ykoz.net> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed>Hi List,>Being very new to Xen I have a few generic questions for the list, I >hope to grab some useful advice and pointers to documentation.>I am evaluating Xen to consolidate a few existing servers into one >appliance (mainly in order to reduce power consumption, heat, and >hardware failure risks). I plan to have a SER router, an Asterisk LCR >router, a voicemail server, a calling card server and maybe even a MySQL >server, all in one box.>In order to do this, I have ordered a dell poweredge 1850 bi-xeon, 4 gb >ecc ram, and raid 1 SCSI disks. It also has dual power supplies and dual >port network cards. The idea is to have redundancy wherever possible in >order to lower the risk of server downtime.>I would like to know if there is a "getting started" howto somewhere I >could play with on a test server before my production server comes in.See http://wiki.xensource.com/xenwiki/XenDocs for links.>Also I would like to know if there are known issues with the hardware I >have ordered.There are several instances of Dell 1850s in our database of machines that ran through all tests on the Xen 3 TestCD; take a look: http://www.xensource.com/community/xen30testing/summary.php>I plan to use debian sarge for the host and all the virtual servers, >does it sound like a reasonable choice for Xen?As far as I know.>Is it possible to "migrate" a virtual machine to a completely different >PC (with different hardware specs)? That would be a very useful feature >to have for upgradability.Yes, with some obvious limitations. Of course the remote PC must be running Xen. It also must be on the same subnet, and to live-migrate its storage must be mountable by both machines. It also needs to be able support the same configuration of the VM. For example, if the VM is using 512MB of RAM on a physical host with 1 GB, it''s not going to work if the remote PC has too little RAM to allocate to it, e.g. 512 MB of physical memory -- less than that is available to the VM because of the Xen Dom0 and overhead.>Finally, are there consultants available for remote training and >support? It would be handy to have someone who can help while I go >through the process of getting Xen to work.Contact XenSource, Inc. See http://www.xensource.com/support/>Best Regards, >Jean-Michel.>-- >Jean-Michel Hiver - http://ykoz.net/ >Découvrez la Réunion des Technologies IP & Telecom >TEL: +262 (0)262 55 03 98 - RCS 434 273 330 SAINT PIERRE_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jean-Michel Hiver wrote:> In order to do this, I have ordered a dell poweredge 1850 bi-xeon, 4 > gb ecc ram, and raid 1 SCSI disks. It also has dual power supplies and > dual port network cards. The idea is to have redundancy wherever > possible in order to lower the risk of server downtime.Sounds smart.> I would like to know if there is a "getting started" howto somewhere I > could play with on a test server before my production server comes in. > Also I would like to know if there are known issues with the hardware > I have ordered. > > I plan to use debian sarge for the host and all the virtual servers, > does it sound like a reasonable choice for Xen?Yes it is. I would recommend the Sarge packages at deb http://packages.debianbase.de/sarge/i386/xen3 ./> Is it possible to "migrate" a virtual machine to a completely > different PC (with different hardware specs)? That would be a very > useful feature to have for upgradability.Yes. Because Xen completely hides the hardware you can move one or several server to another physical server. You just turn the server off and use your favorite tool (rsync, dump/restore or dd) to copy the files within the virtual server or the whole filesystem(s). If you go nuts and by a SAN for your servers you can even do this process without halting the servers. Per. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> Yes it is. I would recommend the Sarge packages at > > deb http://packages.debianbase.de/sarge/i386/xen3 ./ > >> Is it possible to "migrate" a virtual machine to a completely >> different PC (with different hardware specs)? That would be a very >> useful feature to have for upgradability. > > > Yes. Because Xen completely hides the hardware you can move one or > several server to another physical server. You just turn the server > off and use your favorite tool (rsync, dump/restore or dd) to copy the > files within the virtual server or the whole filesystem(s). If you go > nuts and by a SAN for your servers you can even do this process > without halting the servers.Wow! This sounds very cool. If Xen really *does* completely hide the underlying hardware, so that virtual OSes running have no "way" of knowing what their hardware is, I really see it as a big plus. I think I can tolerate about 1 hour of downtime per server if the work is done at night, so I guess migration won''t be a big issue then. Cheers, Jean-Michel. -- Jean-Michel Hiver - http://ykoz.net/ Découvrez la Réunion des Technologies IP & Telecom TEL: +262 (0)262 55 03 98 - RCS 434 273 330 SAINT PIERRE _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Jean-Michel Hiver wrote:> In order to do this, I have ordered a dell poweredge 1850 bi-xeon, 4 gb > ecc ram, and raid 1 SCSI disks. It also has dual power supplies and dual > port network cards. The idea is to have redundancy wherever possible in > order to lower the risk of server downtime.> Also I would like to know if there are known issues with > the hardware I have ordered.The only hardware manufacturer which I can remember reading about having problems with Xen recently on this list is Dell. I think there''s a USB issue with Dell hardware, machines go locking up or something like that. Search the archives?> Is it possible to "migrate" a virtual machine to a completely different > PC (with different hardware specs)?It needs to have the same CPU. Maybe you can work around this by compiling your kernel to a CPU which has a superset of the features of the individual CPUs you plan to use, eg. i686. All your executables would need to be compiled to target this CPU too. Different CPUs may still cause problems if you use code which has sections written for a particular CPU and runtime autodetection of CPU capabilities. Linux MD comes to mind.> That would be a very useful feature to have for upgradability.If you''re permanently upgrading then you''re only going to do it once, so there''s probably less of a problem.. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Am Freitag, 27. Januar 2006 20:26 schrieb Per Andreas Buer:> Jean-Michel Hiver wrote: > > In order to do this, I have ordered a dell poweredge 1850 bi-xeon, 4 > > gb ecc ram, and raid 1 SCSI disks. It also has dual power supplies and > > dual port network cards. The idea is to have redundancy wherever > > possible in order to lower the risk of server downtime. > > Sounds smart. > > > I would like to know if there is a "getting started" howto somewhere I > > could play with on a test server before my production server comes in. > > Also I would like to know if there are known issues with the hardware > > I have ordered. > > > > I plan to use debian sarge for the host and all the virtual servers, > > does it sound like a reasonable choice for Xen? > > Yes it is. I would recommend the Sarge packages at > > deb http://packages.debianbase.de/sarge/i386/xen3 ./I strongly recommend using the pae enabled version or the 64bit version, becaue otherwise not the complete 4gb ram will be useable. 32bit pae enabled version is here: deb http://packages.debianbase.de/sarge/i386/xen3-pae ./ or the 64bit version: deb http://packages.debianbase.de/sarge/amd64/xen3 ./ --Ralph> > Is it possible to "migrate" a virtual machine to a completely > > different PC (with different hardware specs)? That would be a very > > useful feature to have for upgradability. > > Yes. Because Xen completely hides the hardware you can move one or > several server to another physical server. You just turn the server off > and use your favorite tool (rsync, dump/restore or dd) to copy the files > within the virtual server or the whole filesystem(s). If you go nuts and > by a SAN for your servers you can even do this process without halting > the servers. > > > Per. > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Am Samstag, 28. Januar 2006 15:02 schrieb Jean-Michel Hiver:> > Yes it is. I would recommend the Sarge packages at > > > > deb http://packages.debianbase.de/sarge/i386/xen3 ./ > > > >> Is it possible to "migrate" a virtual machine to a completely > >> different PC (with different hardware specs)? That would be a very > >> useful feature to have for upgradability. > > > > Yes. Because Xen completely hides the hardware you can move one or > > several server to another physical server. You just turn the server > > off and use your favorite tool (rsync, dump/restore or dd) to copy the > > files within the virtual server or the whole filesystem(s). If you go > > nuts and by a SAN for your servers you can even do this process > > without halting the servers. > > Wow! This sounds very cool. > > If Xen really *does* completely hide the underlying hardware, so that > virtual OSes running have no "way" of knowing what their hardware is, I > really see it as a big plus.not 100% completely... you will see the real cpu type in /proc/cpuinfo and your xen domain will use all available cpu command sets / features (like sse, mmx, ...) that the real physical cpu offers. This is only a problem for live/no-downtime migration, because if you migrate a xen domain from a cpu with more features to a cpu with less features (or at least not the same features) then your xen domain will reboot immidently after the migration process. For the other way, migration a xen domain from a cpu with less features to a better cpu is not a problem. Your xen domain just will not use the features of the better cpu as long as the domain doesn''t get restarted. But live migration is only possible if you have a san-like solution, because all xen hosts that are involved in the migration has to have access to the same blockdevices at the same location in /dev. If you only want to migrate xen domains from one xen host to another (or even from a real server to a xen system) then you will be fine anyway, because then you don''t need a san or the same cpu specs on all machines. Migration from a real host to a xen system is quite easy. stop the real machine, start it with knoppix or another minimal system where you have some tools available and copy all files (with tar/scp or rsync or ...) to your xen host and copy also the required kernel modules and move /lib/tls away. After that you can start the system again... this time virtualized with xen... with a bit practise you will be able to move real system to xen system in <5-10 min + the time that is needed for copying the files from the real host to the block device (or loop device) on your xen host.> I think I can tolerate about 1 hour of downtime per server if the work > is done at night, so I guess migration won''t be a big issue then.it depend on the size of your servers (amout of data that has to be copied) but I guess you will be faster then 1h/server on normal server systems (webserver, mailserver, etc.). Normale xen is ideal for small to medium sized server, because for the real big ones real physical hardware is better. we have running 13 virtual servers on one dual xeon cpu system with 4GB ram and 300GB HDD (sata + raid5). the cpu load is still ok, but the hdd activity is quite high, so I think about 15-16 virtual system will be the max for us on this system... our customers are all very happy with their virtual servers, no real problems for now. xen definitly rocks :)> > Cheers, > Jean-Michel._______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users