Hi All, I am interested in deploying Xen to replace an existing Virtuozzo based virtual server solution we are currently using. However due to the differences in how it works etc., I would like some clarification on our proposed setup: Firstly, what is the recommended OS for running Xen? We are thinking of using 32bit CentOS 5 as the dom0 OS and probably CentOS 5 domUs as well. Secondly, due to using a 32bit OS, technically we’d be limited to using 4GB ram in the server but I have read Xen is capable of utilising PAE on 32bit systems to utilise more than 4GB ram. So in this case, we would like to use 8GB of ram to split up amongst the Xen VPSes. Will this be fine? Or will Xen not utilise the full 8GB available? Lastly, we need to be able to “upgrade” and “downgrade” a VPS’s disk space easily. Under Virtuozzo all we need to do is change the number of disk blocks allocated and reboot the VPS. Can we do something similar with Xen, for instance using LVM partitions? I have read you can either allocate a normal non-LVM partition, a LVM partition or a file based partition as the “disk” for the VPS. I am looking for a way to easily increase or decrease the space a VPS has without having to be fiddling with partition tables and resizing manually using fdisk. Thanks in advance to anyone who can give me answers to the above! Regards, Alan _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi Rob, Basically there’s 2 reasons why I’m looking at Xen: 1. Cost of licencing for Virtuozzo which is based on how many CPUs etc. 2. Xen has better IO performance compared to Virtuozzo. It’s been shown on a few forums that Xen can have 3 times the disk IO performance. Does anyone have any answers to my original questions? Regards, Alan -----Original Message----- From: Rob Gingell [mailto:gingell@cassatt.com] Sent: Thursday, 7 August 2008 5:39 AM To: Alan Lam Subject: Re: [Xen-users] Xen Setup Alan wrote:> I am interested in deploying Xen to replace an existing Virtuozzobased> virtual server solution we are currently using.I''m curious about your shift from Virtuozzo: is that because you needed something other than Virtuozzo does? or because Virtuozzo proved to be ineffective in some way? I''m asking because I''m being urged to work with Virtuozzo, and wanted to know if there were some pitfalls in using it that were evident in people''s experiences with it. Appreciate any thoughts you can share. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
I have both and Virtuozzo has less overhead then Xen. It is the reverse. I use XEN because I need to virtualize Windows along with Linux. But rest assured, OpenVZ and Virtuozzo are one or several steps ahead. The management tools are far more sophisticated in Virtuozzo and the support is amazing, it cannot be compared. From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Alan Sent: Wednesday, August 06, 2008 8:52 PM To: gingell Cc: xen-users Subject: RE: [Xen-users] Xen Setup Hi Rob, Basically there’s 2 reasons why I’m looking at Xen: 1. Cost of licencing for Virtuozzo which is based on how many CPUs etc. 2. Xen has better IO performance compared to Virtuozzo. It’s been shown on a few forums that Xen can have 3 times the disk IO performance. Does anyone have any answers to my original questions? Regards, Alan -----Original Message----- From: Rob Gingell [mailto:gingell@cassatt.com] Sent: Thursday, 7 August 2008 5:39 AM To: Alan Lam Subject: Re: [Xen-users] Xen Setup Alan wrote:> I am interested in deploying Xen to replace an existing Virtuozzo based> virtual server solution we are currently using.I''m curious about your shift from Virtuozzo: is that because you needed something other than Virtuozzo does? or because Virtuozzo proved to be ineffective in some way? I''m asking because I''m being urged to work with Virtuozzo, and wanted to know if there were some pitfalls in using it that were evident in people''s experiences with it. Appreciate any thoughts you can share. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
We don’t do anything fancy really, just the straight out VPS like no other. We don’t map PCI devices to VPSes etc. It really is just an OS on a disk with a memory allocation. Considering you have both, would you be able to give a brief advantages/disadvantages between using OpenVZ and Xen? I have been considering OpenVZ as well as Xen and Xen was looking a little better on the IO performance side. Thing is, we would like to be able to take advantage of the fact the CPU can handle 64bit and would like to run a 64bit Xen host along with 64bit VPSes. I am not sure if Xen can do this or not, nor whether OpenVZ can either. If you look at my original post to the mailing list, we are considering the switchover because of new hardware/newer OS. From: Venefax [mailto:venefax@gmail.com] Sent: Thursday, 7 August 2008 10:57 AM To: Alan Lam; ''gingell'' Cc: ''xen-users'' Subject: RE: [Xen-users] Xen Setup I have both and Virtuozzo has less overhead then Xen. It is the reverse. I use XEN because I need to virtualize Windows along with Linux. But rest assured, OpenVZ and Virtuozzo are one or several steps ahead. The management tools are far more sophisticated in Virtuozzo and the support is amazing, it cannot be compared. From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Alan Sent: Wednesday, August 06, 2008 8:52 PM To: gingell Cc: xen-users Subject: RE: [Xen-users] Xen Setup Hi Rob, Basically there’s 2 reasons why I’m looking at Xen: 1. Cost of licencing for Virtuozzo which is based on how many CPUs etc. 2. Xen has better IO performance compared to Virtuozzo. It’s been shown on a few forums that Xen can have 3 times the disk IO performance. Does anyone have any answers to my original questions? Regards, Alan -----Original Message----- From: Rob Gingell [mailto:gingell@cassatt.com] Sent: Thursday, 7 August 2008 5:39 AM To: Alan Lam Subject: Re: [Xen-users] Xen Setup Alan wrote:> I am interested in deploying Xen to replace an existing Virtuozzobased> virtual server solution we are currently using.I''m curious about your shift from Virtuozzo: is that because you needed something other than Virtuozzo does? or because Virtuozzo proved to be ineffective in some way? I''m asking because I''m being urged to work with Virtuozzo, and wanted to know if there were some pitfalls in using it that were evident in people''s experiences with it. Appreciate any thoughts you can share. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Wed, Aug 6, 2008 at 11:56 AM, Alan <alan@tdknights.com> wrote:> Hi All, > > > > I am interested in deploying Xen to replace an existing Virtuozzo based > virtual server solution we are currently using. However due to the > differences in how it works etc., I would like some clarification on our > proposed setup: > > > > Firstly, what is the recommended OS for running Xen? We are thinking of > using 32bit CentOS 5 as the dom0 OS and probably CentOS 5 domUs as well. >CentOS base and CentOS guests are well-supported and known to work. There really isn''t a recommended OS, it is more a matter of preference. It may also matter what support, applications or scenarios you hope to achieve, but more likely it is a matter a preference.> > > Secondly, due to using a 32bit OS, technically we''d be limited to using 4GB > ram in the server but I have read Xen is capable of utilising PAE on 32bit > systems to utilise more than 4GB ram. So in this case, we would like to use > 8GB of ram to split up amongst the Xen VPSes. Will this be fine? Or will Xen > not utilise the full 8GB available? > >Xen 32bit + PAE on CentOS supported up to 16 GB of RAM last I heard and saw in the CentOS virtualization docs. Xen will reserve a small amount for the management domain and the hypervisor itself, the rest can be used for guests.> > Lastly, we need to be able to "upgrade" and "downgrade" a VPS''s disk space > easily. Under Virtuozzo all we need to do is change the number of disk > blocks allocated and reboot the VPS. Can we do something similar with Xen, > for instance using LVM partitions? I have read you can either allocate a > normal non-LVM partition, a LVM partition or a file based partition as the > "disk" for the VPS. I am looking for a way to easily increase or decrease > the space a VPS has without having to be fiddling with partition tables and > resizing manually using fdisk. > >Xen can work similarly with LVM partitions. I am curious about the application load, is it disk intensive? Also, are you switching to Xen to gain performance isolation properties? For simply pure performance I would expect openVZ to be better in general, but if you need the isolation properties and performance, then Xen is a good choice. Hope that helps, Todd -- Todd Deshane http://todddeshane.net check out our book: http://runningxen.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, On Wed, 2008-08-06 at 18:03 -0700, Alan wrote:> We don’t do anything fancy really, just the straight out VPS like no > other. We don’t map PCI devices to VPSes etc. It really is just an OS > on a disk with a memory allocation. > > > > Considering you have both, would you be able to give a brief > advantages/disadvantages between using OpenVZ and Xen? I have been > considering OpenVZ as well as Xen and Xen was looking a little better > on the IO performance side. >Xen has no real advantages over Virtuozzo with I/O, although it is very easy to integrate SAN solutions like ATA-over-Ethernet and iSCSI. I have a fairly large cluster mostly fed by an ATA-over-Ethernet meshed SAN, and the performance is quite acceptable.> > > Thing is, we would like to be able to take advantage of the fact the > CPU can handle 64bit and would like to run a 64bit Xen host along with > 64bit VPSes. I am not sure if Xen can do this or not, nor whether > OpenVZ can either. >Roughly 98% of my customers are on x86-64 instances. Approximately 20 are still on x86-32 instances. All of our dom0''s except for one node is x86-64 capable (dual Opteron 2216 hardware from Rackable Systems). Personally, I have found that Xen''s behaviour is a lot more reliable on x86-64 than it is on x86-32. But maybe that''s just my setup.> > > If you look at my original post to the mailing list, we are > considering the switchover because of new hardware/newer OS. >What hardware do you have? Virtuozzo''s memory overcommitting would probably be useful to you if you are working with lowspec hardware (<8GB). I know that with Xen, we have reached capacity limits a few times because the customer growth was increasing more rapidly than we could order and rack more hardware for the clusters. Furthermore, anything I have said about Virtuozzo can be applied to OpenVZ without much difficulty. William _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Venefax wrote:> I have both and Virtuozzo has less overhead then Xen. It is the > reverse. I use XEN because I need to virtualize Windows along with > Linux. But rest assured, OpenVZ and Virtuozzo are one or several steps > ahead. The management tools are far more sophisticated in Virtuozzo and > the support is amazing, it cannot be compared.Its not really fair to compare Xen and OpenVZ/Virtuozzo. Xen is a virtualisation environment. OpenVZ/Virtuozzo is, effectively, a chroot environment. On steroids, but chroot no less. I''ve tried OpenVZ and I can say, hand on heart, I would not be prepared to use it in a production environment. Too many risks.> *From:* xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] *On Behalf Of *Alan > *Sent:* Wednesday, August 06, 2008 8:52 PM > *To:* gingell > *Cc:* xen-users > *Subject:* RE: [Xen-users] Xen Setup > > > > Hi Rob, > > > > Basically there’s 2 reasons why I’m looking at Xen: > > > > 1. Cost of licencing for Virtuozzo which is based on how many CPUs etc. > > 2. Xen has better IO performance compared to Virtuozzo. It’s been shown > on a few forums that Xen can have 3 times the disk IO performance. > > > > Does anyone have any answers to my original questions? > > > > Regards, > > Alan > > > > -----Original Message----- > From: Rob Gingell [mailto:gingell@cassatt.com] > Sent: Thursday, 7 August 2008 5:39 AM > To: Alan Lam > Subject: Re: [Xen-users] Xen Setup > > > > Alan wrote: > >> I am interested in deploying Xen to replace an existing Virtuozzo based > >> virtual server solution we are currently using. > > > > I''m curious about your shift from Virtuozzo: is that because you needed > > something other than Virtuozzo does? or because Virtuozzo proved to be > > ineffective in some way? > > > > I''m asking because I''m being urged to work with Virtuozzo, and wanted to > > know if there were some pitfalls in using it that were evident in > > people''s experiences with it. > > > > Appreciate any thoughts you can share. > > > > > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > 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
Hi Todd, Thanks for your reply. I am after something that will provide more than just a chroot-based environment for the VPS. Virtuozzo/OpenVZ is effectively a chroot environment if you look at its filesystem structure. The CPU will have Virtualisation Technology and 64bit capability which is why I am exploring a full virtualisation type of setup rather than a chrooted one. With a LVM partition setup, I assume I can use the LVM tools to easily resize a partition/filesystem to cater for more space/less space needed on a certain VPS? -Alan -----Original Message----- From: Todd Deshane [mailto:deshantm@gmail.com] Sent: Thursday, 7 August 2008 11:50 AM To: Alan Lam Cc: xen-users Subject: Re: [Xen-users] Xen Setup On Wed, Aug 6, 2008 at 11:56 AM, Alan <alan@tdknights.com> wrote:> Hi All,>>>> I am interested in deploying Xen to replace an existing Virtuozzobased> virtual server solution we are currently using. However due to the> differences in how it works etc., I would like some clarification onour> proposed setup:>>>> Firstly, what is the recommended OS for running Xen? We are thinkingof> using 32bit CentOS 5 as the dom0 OS and probably CentOS 5 domUs aswell.>CentOS base and CentOS guests are well-supported and known to work. There really isn''t a recommended OS, it is more a matter of preference. It may also matter what support, applications or scenarios you hope to achieve, but more likely it is a matter a preference.>>> Secondly, due to using a 32bit OS, technically we''d be limited tousing 4GB> ram in the server but I have read Xen is capable of utilising PAE on32bit> systems to utilise more than 4GB ram. So in this case, we would liketo use> 8GB of ram to split up amongst the Xen VPSes. Will this be fine? Orwill Xen> not utilise the full 8GB available?>>Xen 32bit + PAE on CentOS supported up to 16 GB of RAM last I heard and saw in the CentOS virtualization docs. Xen will reserve a small amount for the management domain and the hypervisor itself, the rest can be used for guests.>> Lastly, we need to be able to "upgrade" and "downgrade" a VPS''s diskspace> easily. Under Virtuozzo all we need to do is change the number of disk> blocks allocated and reboot the VPS. Can we do something similar withXen,> for instance using LVM partitions? I have read you can either allocatea> normal non-LVM partition, a LVM partition or a file based partition asthe> "disk" for the VPS. I am looking for a way to easily increase ordecrease> the space a VPS has without having to be fiddling with partitiontables and> resizing manually using fdisk.>>Xen can work similarly with LVM partitions. I am curious about the application load, is it disk intensive? Also, are you switching to Xen to gain performance isolation properties? For simply pure performance I would expect openVZ to be better in general, but if you need the isolation properties and performance, then Xen is a good choice. Hope that helps, Todd -- Todd Deshane http://todddeshane.net check out our book: http://runningxen.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi William, Thanks for your reply. Basically I would like to utilise x86_64 especially since the hardware supports it. I will be working with hardware that will have 8GB ram. The idea is a VPS will be allocated x amount of ram that should be a hard limit similar to how a normal dedicated server would behave when you hit your physical ram limit. Disk IO will be fairly moderate, and won’t be beyond fairly standard levels. -Alan -----Original Message----- From: William Pitcock [mailto:nenolod@sacredspiral.co.uk] Sent: Thursday, 7 August 2008 12:15 PM To: Alan Lam Cc: venefax; xen-users Subject: RE: [Xen-users] Xen Setup Hi, On Wed, 2008-08-06 at 18:03 -0700, Alan wrote:> We don’t do anything fancy really, just the straight out VPS like no> other. We don’t map PCI devices to VPSes etc. It really is just an OS> on a disk with a memory allocation.>>>> Considering you have both, would you be able to give a brief> advantages/disadvantages between using OpenVZ and Xen? I have been> considering OpenVZ as well as Xen and Xen was looking a little better> on the IO performance side.>Xen has no real advantages over Virtuozzo with I/O, although it is very easy to integrate SAN solutions like ATA-over-Ethernet and iSCSI. I have a fairly large cluster mostly fed by an ATA-over-Ethernet meshed SAN, and the performance is quite acceptable.>>> Thing is, we would like to be able to take advantage of the fact the> CPU can handle 64bit and would like to run a 64bit Xen host along with> 64bit VPSes. I am not sure if Xen can do this or not, nor whether> OpenVZ can either.>Roughly 98% of my customers are on x86-64 instances. Approximately 20 are still on x86-32 instances. All of our dom0''s except for one node is x86-64 capable (dual Opteron 2216 hardware from Rackable Systems). Personally, I have found that Xen''s behaviour is a lot more reliable on x86-64 than it is on x86-32. But maybe that''s just my setup.>>> If you look at my original post to the mailing list, we are> considering the switchover because of new hardware/newer OS.>What hardware do you have? Virtuozzo''s memory overcommitting would probably be useful to you if you are working with lowspec hardware (<8GB). I know that with Xen, we have reached capacity limits a few times because the customer growth was increasing more rapidly than we could order and rack more hardware for the clusters. Furthermore, anything I have said about Virtuozzo can be applied to OpenVZ without much difficulty. William _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, Aug 7, 2008 at 12:22 AM, Alan <alan@tdknights.com> wrote:> Hi Todd, > > > > Thanks for your reply. I am after something that will provide more than just > a chroot-based environment for the VPS. Virtuozzo/OpenVZ is effectively a > chroot environment if you look at its filesystem structure. > >I don''t actually know the guts of OpenVZ, but implementing performance isolation in OS level virtualization (such as openVZ, solaris zones, etc.) has been notoriously difficult. In Xen, the situation has been better in general.> > The CPU will have Virtualisation Technology and 64bit capability which is > why I am exploring a full virtualisation type of setup rather than a > chrooted one. >So do you plan to make use of unmodified guests, i.e. do you hope to support Windows or the like?> > > With a LVM partition setup, I assume I can use the LVM tools to easily > resize a partition/filesystem to cater for more space/less space needed on a > certain VPS? >Yes, the current state of the art requires rebooting the guest, but this is likely not to be the case in a general sense for long. There are probably even really tricky ways to get online resizing of a file system to work for a guest, but it is not generally supported yet (that I know of). Also for a general reference on Xen, check out our "Running Xen" book. Cheers, Todd -- Todd Deshane http://todddeshane.net check out our book: http://runningxen.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi Todd, Thanks for your reply, the performance isolation helps – primarily so that one VPS being chewed up won’t affect another too adversely. The ability to run Windows would be good, but not essential. With virtualisation technology support from the CPU – would it be possible to run Windows unmodified? I am not fussed about having to reboot the domU to have the LVM partition size upgrade/downgrade take effect. That is fine, only takes 2-3 minutes at most for it to come back up etc. Online resize isn’t necessary for my application. -Alan -----Original Message----- From: Todd Deshane [mailto:deshantm@gmail.com] Sent: Thursday, 7 August 2008 2:35 PM To: Alan Lam Cc: xen-users Subject: Re: [Xen-users] Xen Setup On Thu, Aug 7, 2008 at 12:22 AM, Alan <alan@tdknights.com> wrote:> Hi Todd,>>>> Thanks for your reply. I am after something that will provide morethan just> a chroot-based environment for the VPS. Virtuozzo/OpenVZ iseffectively a> chroot environment if you look at its filesystem structure.>>I don''t actually know the guts of OpenVZ, but implementing performance isolation in OS level virtualization (such as openVZ, solaris zones, etc.) has been notoriously difficult. In Xen, the situation has been better in general.>> The CPU will have Virtualisation Technology and 64bit capability whichis> why I am exploring a full virtualisation type of setup rather than a> chrooted one.>So do you plan to make use of unmodified guests, i.e. do you hope to support Windows or the like?>>> With a LVM partition setup, I assume I can use the LVM tools to easily> resize a partition/filesystem to cater for more space/less spaceneeded on a> certain VPS?>Yes, the current state of the art requires rebooting the guest, but this is likely not to be the case in a general sense for long. There are probably even really tricky ways to get online resizing of a file system to work for a guest, but it is not generally supported yet (that I know of). Also for a general reference on Xen, check out our "Running Xen" book. Cheers, Todd -- Todd Deshane http://todddeshane.net check out our book: http://runningxen.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Thu, Aug 7, 2008 at 1:02 AM, Alan <alan@tdknights.com> wrote:> Hi Todd, > > > > Thanks for your reply, the performance isolation helps – primarily so that > one VPS being chewed up won''t affect another too adversely. > > > > The ability to run Windows would be good, but not essential. With > virtualisation technology support from the CPU – would it be possible to run > Windows unmodified? > >Yeah, with Intel-VT or AMD-V, running Windows is possible. In Xen terminology, an unmodified guest is called an HVM guest.> > I am not fussed about having to reboot the domU to have the LVM partition > size upgrade/downgrade take effect. That is fine, only takes 2-3 minutes at > most for it to come back up etc. Online resize isn''t necessary for my > application. > > > > -Alan > > > > -----Original Message----- > From: Todd Deshane [mailto:deshantm@gmail.com] > Sent: Thursday, 7 August 2008 2:35 PM > To: Alan Lam > Cc: xen-users > Subject: Re: [Xen-users] Xen Setup > > > > On Thu, Aug 7, 2008 at 12:22 AM, Alan <alan@tdknights.com> wrote: > >> Hi Todd, > >> > >> > >> > >> Thanks for your reply. I am after something that will provide more than >> just > >> a chroot-based environment for the VPS. Virtuozzo/OpenVZ is effectively a > >> chroot environment if you look at its filesystem structure. > >> > >> > > > > I don''t actually know the guts of OpenVZ, but implementing performance > isolation > > in OS level virtualization (such as openVZ, solaris zones, etc.) has > > been notoriously > > difficult. In Xen, the situation has been better in general. > > > > > >> > >> The CPU will have Virtualisation Technology and 64bit capability which is > >> why I am exploring a full virtualisation type of setup rather than a > >> chrooted one. > >> > > > > So do you plan to make use of unmodified guests, i.e. do you hope to support > > Windows or the like? > > > >> > >> > >> With a LVM partition setup, I assume I can use the LVM tools to easily > >> resize a partition/filesystem to cater for more space/less space needed on >> a > >> certain VPS? > >> > > > > Yes, the current state of the art requires rebooting the guest, but > > this is likely > > not to be the case in a general sense for long. There are probably even > really > > tricky ways to get online resizing of a file system to work for a guest, but > it > > is not generally supported yet (that I know of). > > > > Also for a general reference on Xen, check out our "Running Xen" book. > > > > Cheers, > > Todd > > > > -- > > Todd Deshane > > http://todddeshane.net > > check out our book: http://runningxen.com > > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users >-- Todd Deshane http://todddeshane.net check out our book: http://runningxen.com _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users