Dear all, I would like to know how many Windows2003 I can run on 2 dual core 3Ghz with more than 16 Go RAM. - theory? - real life(experience)? My hardware is VT enable Thanks, Antoine N. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Petersson, Mats
2006-Aug-08 08:55 UTC
RE: [Xen-users] How many Windows2003 on VT or pacifica
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Antoine Nivard > Sent: 08 August 2006 07:26 > To: xen-users@lists.xensource.com > Subject: [Xen-users] How many Windows2003 on VT or pacifica > > Dear all, > > I would like to know how many Windows2003 I can run on 2 dual > core 3Ghz > with more than 16 Go RAM. > - theory? > - real life(experience)?In short: How long is a piece of string? That are idle, or that are doing something useful? What application(s) are you planning to run? How much memory does each instance of Win2K3 need? How much Disk, Network and CPU utilization does it use? There''s no limit to the number of HVM guests (well, there is, but it''s like 100 or more in 32 bit - if you run 64-bit it''s ALMOST unlimited, but may require passing extra arguments to Xen at boot), the real limit will be how much CPU processing is needed to emulate the devices used by the guests, plus the amount of CPU needed to support the guest properly (with the credit scheduler this will be more stable than with the older schedulers!) and how much memory you give each guest. And that in turn will be determined by what you''re doing within the guest. It''s perfectly possible to make a dual processor machine without virtualization buckle at the knees from strain if you give it the right load(s), so, as virtualization adds load to the processor, you can obviously expect that the machine can start to cause trouble even with one instance of Win2K3 under the "right" (or wrong) circumstances. [Those circumstances are of course when the system isn''t correctly configured for the number of users or the type of load it''s been given - not enough memory or number of CPU''s for example] On the other hand, most Windows servers are running 15-30% of the CPU capacity, and nowhere near any of the other hardware limits, so you could probably run 2-5 of these in a single server. But there will be some (sometimes significant) overhead in the virtualization situation - particularly if there is high levels of hardware emulation involved (in the current implementation for Windows, ALL hardware is emulated - network, hard-disk, timers, graphics, keyboard, mouse, etc, etc). So a very disk-intensive application would have significantly increased CPU usage over the non-virtual version. Work is in progress to improve this, but it''s quite clear that for the foreseeable future (several years), there will be some overhead in virtualizing the hardware, even if some extra hardware features are being added to help the processor deal with the virtualization of other hardware components. In the future, it should be possible to give each guest it''s own hard-disk controller, and then the overhead would for disk-accesses would be eliminated - but any hardware that is shared must be "shared safely", which means that software needs to be involved in keeping track of what''s going on in one way or another - how and where can make a small difference, but it''s still overhead compared to the "non-virtual solution". -- Mats> > > My hardware is VT enable > > Thanks, > Antoine N. > > _______________________________________________ > 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
Antoine Nivard
2006-Aug-09 11:32 UTC
Re: [Xen-users] How many Windows2003 on VT or pacifica
Mats, Thanks for your reply. I am agry for your analyse. But with my question, I would like to know if we can have more than 1 Windows on Xen. If 4/5 VM per CPU is possible, with Windows as VM, for me it''s ok Thanks, Antoine N. Petersson, Mats a écrit :>> -----Original Message----- >> From: xen-users-bounces@lists.xensource.com >> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of >> Antoine Nivard >> Sent: 08 August 2006 07:26 >> To: xen-users@lists.xensource.com >> Subject: [Xen-users] How many Windows2003 on VT or pacifica >> >> Dear all, >> >> I would like to know how many Windows2003 I can run on 2 dual >> core 3Ghz >> with more than 16 Go RAM. >> - theory? >> - real life(experience)? >> > > In short: How long is a piece of string? > > That are idle, or that are doing something useful? > > What application(s) are you planning to run? > > How much memory does each instance of Win2K3 need? > > How much Disk, Network and CPU utilization does it use? > > There''s no limit to the number of HVM guests (well, there is, but it''s > like 100 or more in 32 bit - if you run 64-bit it''s ALMOST unlimited, > but may require passing extra arguments to Xen at boot), the real limit > will be how much CPU processing is needed to emulate the devices used by > the guests, plus the amount of CPU needed to support the guest properly > (with the credit scheduler this will be more stable than with the older > schedulers!) and how much memory you give each guest. And that in turn > will be determined by what you''re doing within the guest. It''s perfectly > possible to make a dual processor machine without virtualization buckle > at the knees from strain if you give it the right load(s), so, as > virtualization adds load to the processor, you can obviously expect that > the machine can start to cause trouble even with one instance of Win2K3 > under the "right" (or wrong) circumstances. [Those circumstances are of > course when the system isn''t correctly configured for the number of > users or the type of load it''s been given - not enough memory or number > of CPU''s for example] > > On the other hand, most Windows servers are running 15-30% of the CPU > capacity, and nowhere near any of the other hardware limits, so you > could probably run 2-5 of these in a single server. But there will be > some (sometimes significant) overhead in the virtualization situation - > particularly if there is high levels of hardware emulation involved (in > the current implementation for Windows, ALL hardware is emulated - > network, hard-disk, timers, graphics, keyboard, mouse, etc, etc). So a > very disk-intensive application would have significantly increased CPU > usage over the non-virtual version. Work is in progress to improve this, > but it''s quite clear that for the foreseeable future (several years), > there will be some overhead in virtualizing the hardware, even if some > extra hardware features are being added to help the processor deal with > the virtualization of other hardware components. In the future, it > should be possible to give each guest it''s own hard-disk controller, and > then the overhead would for disk-accesses would be eliminated - but any > hardware that is shared must be "shared safely", which means that > software needs to be involved in keeping track of what''s going on in one > way or another - how and where can make a small difference, but it''s > still overhead compared to the "non-virtual solution". > > -- > Mats > >> My hardware is VT enable >> >> Thanks, >> Antoine N. >> >> _______________________________________________ >> 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
Petersson, Mats
2006-Aug-09 11:47 UTC
RE: [Xen-users] How many Windows2003 on VT or pacifica
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Antoine Nivard > Sent: 09 August 2006 12:33 > To: xen-users@lists.xensource.com > Subject: Re: [Xen-users] How many Windows2003 on VT or pacifica > > Mats, > > Thanks for your reply. > > I am agry for your analyse. But with my question, I would > like to know if we can have more than 1 Windows on Xen.You can definitely run more than one Windows instance on one machine with Xen, no worries there... But the performance and well-behaving of the system will to a large extent depend on what you''re actually doing within that Windows guest - is it just sitting there answering the odd Web-request, or is it a very busy file-/mail-server for a big office?> > If 4/5 VM per CPU is possible, with Windows as VM, for me it''s okIt''s POSSIBLE, but I wouldn''t recommend it if you''ve got more than a little bit of load on any of the machines... -- Mats> > Thanks, > > Antoine N. > > > > > Petersson, Mats a écrit : > >> -----Original Message----- > >> From: xen-users-bounces@lists.xensource.com > >> [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > >> Antoine Nivard > >> Sent: 08 August 2006 07:26 > >> To: xen-users@lists.xensource.com > >> Subject: [Xen-users] How many Windows2003 on VT or pacifica > >> > >> Dear all, > >> > >> I would like to know how many Windows2003 I can run on 2 dual > >> core 3Ghz > >> with more than 16 Go RAM. > >> - theory? > >> - real life(experience)? > >> > > > > In short: How long is a piece of string? > > > > That are idle, or that are doing something useful? > > > > What application(s) are you planning to run? > > > > How much memory does each instance of Win2K3 need? > > > > How much Disk, Network and CPU utilization does it use? > > > > There''s no limit to the number of HVM guests (well, there > is, but it''s > > like 100 or more in 32 bit - if you run 64-bit it''s ALMOST > unlimited, > > but may require passing extra arguments to Xen at boot), > the real limit > > will be how much CPU processing is needed to emulate the > devices used by > > the guests, plus the amount of CPU needed to support the > guest properly > > (with the credit scheduler this will be more stable than > with the older > > schedulers!) and how much memory you give each guest. And > that in turn > > will be determined by what you''re doing within the guest. > It''s perfectly > > possible to make a dual processor machine without > virtualization buckle > > at the knees from strain if you give it the right load(s), so, as > > virtualization adds load to the processor, you can > obviously expect that > > the machine can start to cause trouble even with one > instance of Win2K3 > > under the "right" (or wrong) circumstances. [Those > circumstances are of > > course when the system isn''t correctly configured for the number of > > users or the type of load it''s been given - not enough > memory or number > > of CPU''s for example] > > > > On the other hand, most Windows servers are running 15-30% > of the CPU > > capacity, and nowhere near any of the other hardware limits, so you > > could probably run 2-5 of these in a single server. But > there will be > > some (sometimes significant) overhead in the virtualization > situation - > > particularly if there is high levels of hardware emulation > involved (in > > the current implementation for Windows, ALL hardware is emulated - > > network, hard-disk, timers, graphics, keyboard, mouse, etc, > etc). So a > > very disk-intensive application would have significantly > increased CPU > > usage over the non-virtual version. Work is in progress to > improve this, > > but it''s quite clear that for the foreseeable future > (several years), > > there will be some overhead in virtualizing the hardware, > even if some > > extra hardware features are being added to help the > processor deal with > > the virtualization of other hardware components. In the future, it > > should be possible to give each guest it''s own hard-disk > controller, and > > then the overhead would for disk-accesses would be > eliminated - but any > > hardware that is shared must be "shared safely", which means that > > software needs to be involved in keeping track of what''s > going on in one > > way or another - how and where can make a small difference, but it''s > > still overhead compared to the "non-virtual solution". > > > > -- > > Mats > > > >> My hardware is VT enable > >> > >> Thanks, > >> Antoine N. > >> > >> _______________________________________________ > >> 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 > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users