Hi all, Our company is going to buy a new server for Xen. We are gonna run Fedora 6 as the domain0, and put about 4-5 guests on it(it may include window). Can anyone give me some advice about the hardware for the new server, such as memory, vieo card, cpu, motherboard, and harddisk(scsi raid???). I am too worried about that the new server is not suitable for xen after purchasing it. Many many thanks! and sorry for my english. xin _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, Xin Chen wrote:> Hi all, > > Our company is going to buy a new server for Xen. We are gonna run > Fedora 6 as the domain0, and put about 4-5 guests on it(it may include > window). Can anyone give me some advice about the hardware for the new > server, such as memory, vieo card, cpu, motherboard, and harddisk(scsi > raid???). >From my point of view there are only two main parts for your server:Memory and cpu. Use CPUs with Full virtualization and as much as memory as you can get. Memory will always your limiting factor. Beside this maybe fast disks will be an enhancment to your server, but they matter the same than on a normal server. Jan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Thanks for that. What about a VT-supported cpu to do the para-virtualization instead of full-virtualization? which one is better. ps: just wondering, if I copy one guest system image file from one xen server to another xen server, does that work? VMware does, I don''t know xen could or not, cause it seems the drivers may be missing. many thanks. sorry about my english xin Jan Albrecht wrote:> > Hi, > Xin Chen wrote: >> Hi all, >> >> Our company is going to buy a new server for Xen. We are gonna run >> Fedora 6 as the domain0, and put about 4-5 guests on it(it may include >> window). Can anyone give me some advice about the hardware for the new >> server, such as memory, vieo card, cpu, motherboard, and harddisk(scsi >> raid???). >>From my point of view there are only two main parts for your server: > Memory and cpu. Use CPUs with Full virtualization and as much as memory > as you can get. Memory will always your limiting factor. > Beside this maybe fast disks will be an enhancment to your server, but > they matter the same than on a normal server. > > Jan > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > >-- View this message in context: http://www.nabble.com/a-new-server-for-Xen-tf3306769.html#a9198889 Sent from the Xen - User mailing list archive at Nabble.com. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of xin > Sent: 28 February 2007 07:02 > To: xen-users@lists.xensource.com > Subject: Re: [Xen-users] a new server for Xen > > > Thanks for that. What about a VT-supported cpu to do the > para-virtualization > instead of full-virtualization? which one is better.In the present form of hardware supported (full) virtualization, there''s one important feature of this technology that makes it "win" over Para-virtualization: You can virtualize OS''s that there''s no publicly available para-virtual support for, for example those OS''s that don''t have source-code easily available, or where no one has spent the several months of effort to make the para-virtualization work. Para-virtualization will almost always win over full-virtualization where both are possible: The PV-model can package up requests so that the hypervisor is called only once per block-request. For example, if a process allocates 1MB of memory, that requires 256 writes to the page-table. The PV-guest can send a list of 256 page-table entries to the hypervisor and say "map these into my page-table X". In the full-virtualization case, each one of those 256 page-table writes will appear as individual writes, each one having to be intercepted, "understood" and acted on by the hypevisor (in a 32-bit PAE-system, you may even get 512 write operations to intercept, as each page-table entry is 64 bits, but the processor is most likely using regular 32-bit store operations). So the overhead for para-virtual operations is less than full virtualization. Whether this is NOTICABLY less or just a few percent depends very much on the type of application and how much of the operations in the guest that needs intercepting. For example a big calculation effort may not require more than a few intercepts per second, whilst something creating/destroying (e.g. kernel compile in Linux) processes a lot will be heavy on intercepts. Somewhere around the halfway mark, you get Web-serving where the network access is quite intense (which requires intercepting) and that uses memory quite dynamically.> > ps: just wondering, if I copy one guest system image file from one xen > server to another xen server, does that work? VMware does, I > don''t know xen > could or not, cause it seems the drivers may be missing.That should work fine. Drivers for the guest-domain should all be the same anyways, all the drivers that you need for one setup should work on the other system, as the "hardware" that the guest sees is all "virtual hardware" that looks the same whatever the "real hardware" is (for example, the guest will not know if you use IDE, SATA or SCSI hard-disks, nor if you use 10Mbps, 100Mbps or 1Gbps network cards). This applies both to para-virtualization and full-virtualization guest models - although the virtual devices are somewhat different between the models. Obviously, if you use the model of letting a guest-domain access REAL hardware (which is possible, but not the common usage model), then you''ll have problems if your "old" machine and "new" machine have different types of hardware, or even if the PCI device ID''s are different. But that''s always the case if you move between REAL hardware models - and that''s exactly why virtual machines have a virtual device layer: the virtual devices are the same whatever the REAL hardware, so you don''t have to worry about device drivers. Further to the "real hardware access from the guest-domain": You can always add the drivers for the new hardware before you move the image-file. -- Mats> > many thanks. sorry about my english > xin > > > Jan Albrecht wrote: > > > > Hi, > > Xin Chen wrote: > >> Hi all, > >> > >> Our company is going to buy a new server for Xen. We are gonna run > >> Fedora 6 as the domain0, and put about 4-5 guests on it(it > may include > >> window). Can anyone give me some advice about the hardware > for the new > >> server, such as memory, vieo card, cpu, motherboard, and > harddisk(scsi > >> raid???). > >>From my point of view there are only two main parts for your server: > > Memory and cpu. Use CPUs with Full virtualization and as > much as memory > > as you can get. Memory will always your limiting factor. > > Beside this maybe fast disks will be an enhancment to your > server, but > > they matter the same than on a normal server. > > > > Jan > > > > _______________________________________________ > > Xen-users mailing list > > Xen-users@lists.xensource.com > > http://lists.xensource.com/xen-users > > > > > > -- > View this message in context: > http://www.nabble.com/a-new-server-for-Xen-tf3306769.html#a9198889 > Sent from the Xen - User mailing list archive at Nabble.com. > > > _______________________________________________ > 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
xin wrote:> Thanks for that. What about a VT-supported cpu to do the para-virtualization > instead of full-virtualization? which one is better.I''ve AMD PV and Intel VT here and from my point of view the VT are much better (and that''s no matter if they''re AMD, Intel or from Mars...), because you can install an OS "out-of-box" to that server. With PV you''re limited to Linux and to special kernels. And the arguments Mats brought up may be right, but as long as you do normal daily business on such a server (file-server, webserver, etc...) at VT machine would always be the better choice. Jan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Jan Albrecht > Sent: 01 March 2007 05:16 > To: xin > Cc: xen-users@lists.xensource.com > Subject: Re: [Xen-users] a new server for Xen > > xin wrote: > > Thanks for that. What about a VT-supported cpu to do the > para-virtualization > > instead of full-virtualization? which one is better. > I''ve AMD PV and Intel VT here and from my point of view the > VT are much > better (and that''s no matter if they''re AMD, Intel or from Mars...), > because you can install an OS "out-of-box" to that server. > With PV you''re limited to Linux and to special kernels. And the > arguments Mats brought up may be right, but as long as you do normal > daily business on such a server (file-server, webserver, etc...) at VT > machine would always be the better choice.Sure, with VT (in my view obviously preferrably from AMD ;-) ) you have ALL the possibilites, rather than just half of them. I should have said so in my post. -- Mats> > Jan > > > _______________________________________________ > 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
But with paravirtualised Linux, with a recompiled kernel, you have better performance. Petersson, Mats a écrit :> > > >> -----Original Message----- >> From: xen-users-bounces@lists.xensource.com >> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Jan Albrecht >> Sent: 01 March 2007 05:16 >> To: xin >> Cc: xen-users@lists.xensource.com >> Subject: Re: [Xen-users] a new server for Xen >> >> xin wrote: >> >>> Thanks for that. What about a VT-supported cpu to do the >> para-virtualization >> >>> instead of full-virtualization? which one is better. >>> >> I''ve AMD PV and Intel VT here and from my point of view the VT are much >> better (and that''s no matter if they''re AMD, Intel or from Mars...), >> because you can install an OS "out-of-box" to that server. >> With PV you''re limited to Linux and to special kernels. And the >> arguments Mats brought up may be right, but as long as you do normal >> daily business on such a server (file-server, webserver, etc...) at VT >> machine would always be the better choice. >> > > Sure, with VT (in my view obviously preferrably from AMD ;-) ) you have > ALL the possibilites, rather than just half of them. I should have said > so in my post. > -- > Mats > >> Jan >> >> >> _______________________________________________ >> 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 > >-- Yves-Gaël Chény Responsable développements techniques Responsable Achats techniques Responsable RH technique 261 route de Clisson 44230 St Sébastien sur Loire Tel : 02 40 97 62 67 - 08 73 77 24 91 http://www.tranquilitsystems.com/ yves-gael.cheny@tranquil-it-systems.fr Tranquil IT Systems . SAS 37 000 ¤ _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > >> -----Original Message----- >> From: xen-users-bounces@lists.xensource.com >> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of >> Jan Albrecht >> Sent: 01 March 2007 05:16 >> To: xin >> Cc: xen-users@lists.xensource.com >> Subject: Re: [Xen-users] a new server for Xen >> >> xin wrote: >> > Thanks for that. What about a VT-supported cpu to do the >> para-virtualization >> > instead of full-virtualization? which one is better. >> I''ve AMD PV and Intel VT here and from my point of view the >> VT are much >> better (and that''s no matter if they''re AMD, Intel or from Mars...), >> because you can install an OS "out-of-box" to that server. >> With PV you''re limited to Linux and to special kernels. And the >> arguments Mats brought up may be right, but as long as you do normal >> daily business on such a server (file-server, webserver, etc...) at VT >> machine would always be the better choice. > > Sure, with VT (in my view obviously preferrably from AMD ;-) ) you have > ALL the possibilites, rather than just half of them. I should have said > so in my post. > > -- > MatsI guess now I''m confused. I thought that AMD PV and Intel VT did basically the same thing. They allowed unmodified OS''s to work with a hypervisor to support full vitrualization. From that Jan said it sounds like there is a draw back of PV vs VT? I haven''t heard anything about that. Can someone explain (I personally prefer AMD)?? Thanks, Ryan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: Ryan Burke [mailto:burke@tailorhosting.com] > Sent: 01 March 2007 14:14 > To: Petersson, Mats > Cc: Jan Albrecht; xin; xen-users@lists.xensource.com > Subject: RE: [Xen-users] a new server for Xen > > > > > > >> -----Original Message----- > >> From: xen-users-bounces@lists.xensource.com > >> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > >> Jan Albrecht > >> Sent: 01 March 2007 05:16 > >> To: xin > >> Cc: xen-users@lists.xensource.com > >> Subject: Re: [Xen-users] a new server for Xen > >> > >> xin wrote: > >> > Thanks for that. What about a VT-supported cpu to do the > >> para-virtualization > >> > instead of full-virtualization? which one is better. > >> I''ve AMD PV and Intel VT here and from my point of view the > >> VT are much > >> better (and that''s no matter if they''re AMD, Intel or from > Mars...), > >> because you can install an OS "out-of-box" to that server. > >> With PV you''re limited to Linux and to special kernels. And the > >> arguments Mats brought up may be right, but as long as you > do normal > >> daily business on such a server (file-server, webserver, > etc...) at VT > >> machine would always be the better choice. > > > > Sure, with VT (in my view obviously preferrably from AMD > ;-) ) you have > > ALL the possibilites, rather than just half of them. I > should have said > > so in my post. > > > > -- > > Mats > > > I guess now I''m confused. I thought that AMD PV and Intel VT > did basically > the same thing. They allowed unmodified OS''s to work with a > hypervisor to > support full vitrualization. From that Jan said it sounds > like there is a > draw back of PV vs VT? I haven''t heard anything about that. > Can someone > explain (I personally prefer AMD)??PV = Para-Virtualization -> modified kernel source-code to make virtual kernel. VT = Virtualization Technology (from either AMD or Intel) allowing UNMODIFIED OS kernels to run on Xen. AMD''s technology is sometimes called SVM or AMD-V, and the combined name for "VT" in Xen is "HVM", which is short for "Hardware Virtual Machine (extensions)". If you look at my e-mail address, you see why I prefer AMD ;-) -- Mats> > Thanks, > Ryan > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
>> -----Original Message----- >> From: Ryan Burke [mailto:burke@tailorhosting.com] >> Sent: 01 March 2007 14:14 >> To: Petersson, Mats >> Cc: Jan Albrecht; xin; xen-users@lists.xensource.com >> Subject: RE: [Xen-users] a new server for Xen >> >> > >> > >> >> -----Original Message----- >> >> From: xen-users-bounces@lists.xensource.com >> >> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of >> >> Jan Albrecht >> >> Sent: 01 March 2007 05:16 >> >> To: xin >> >> Cc: xen-users@lists.xensource.com >> >> Subject: Re: [Xen-users] a new server for Xen >> >> >> >> xin wrote: >> >> > Thanks for that. What about a VT-supported cpu to do the >> >> para-virtualization >> >> > instead of full-virtualization? which one is better. >> >> I''ve AMD PV and Intel VT here and from my point of view the >> >> VT are much >> >> better (and that''s no matter if they''re AMD, Intel or from >> Mars...), >> >> because you can install an OS "out-of-box" to that server. >> >> With PV you''re limited to Linux and to special kernels. And the >> >> arguments Mats brought up may be right, but as long as you >> do normal >> >> daily business on such a server (file-server, webserver, >> etc...) at VT >> >> machine would always be the better choice. >> > >> > Sure, with VT (in my view obviously preferrably from AMD >> ;-) ) you have >> > ALL the possibilites, rather than just half of them. I >> should have said >> > so in my post. >> > >> > -- >> > Mats >> >> >> I guess now I''m confused. I thought that AMD PV and Intel VT >> did basically >> the same thing. They allowed unmodified OS''s to work with a >> hypervisor to >> support full vitrualization. From that Jan said it sounds >> like there is a >> draw back of PV vs VT? I haven''t heard anything about that. >> Can someone >> explain (I personally prefer AMD)?? > > PV = Para-Virtualization -> modified kernel source-code to make virtual > kernel. > VT = Virtualization Technology (from either AMD or Intel) allowing > UNMODIFIED OS kernels to run on Xen. AMD''s technology is sometimes > called SVM or AMD-V, and the combined name for "VT" in Xen is "HVM", > which is short for "Hardware Virtual Machine (extensions)". > > If you look at my e-mail address, you see why I prefer AMD ;-) > > -- > Mats >> >> Thanks, >> Ryan >> >>Sorry, brain fart. I saw AMD PV and was thinking AMD-V. Thanks. Ryan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Yves-gaël Chény wrote:> But with paravirtualised Linux, with a recompiled kernel, you have > better performance.Does not matter until you have heavy io access. During normal daily use VT is much more painless. Jan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Fri, Mar 02, 2007 at 11:52:04AM +0100, Jan Albrecht wrote:> Yves-ga?l Ch?ny wrote: > > But with paravirtualised Linux, with a recompiled kernel, you have > > better performance. > Does not matter until you have heavy io access. During normal daily use > VT is much more painless. >Isn''t heavy io a given for almost all normal applications, other than the purely scientific. All "NORMAL" work the computer does is dependent on on heavy io--whether it be database or webserver or mail server (Not DNS, but even there you have network coming in). I personally prefer the paravirtualized, because, even though the features doesnt'' exist at the point of talking, in that setup you have much greater control over the domU from the dom0, and you can do some nifty mass actions from the host to all the virtual machines. One feature I would like to see in the paravirtualized system is the ability to sync the guest. Thanks. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users