I''ve installed Xen Hypervisor 3.0.3 (CentOS 5.7, i386) inside Virtualbox 4.1.16 (Mageia 1, i686) and have noticed that Dom0 is consuming 85% of the memory allocated to the VM (1GB) so I''d like to reduce this as much as possible in order to make more room for one or two VM''s. Is there a minimum amount of vRAM that can/should be allocated to Dom0 (using the dom0_mem boot parameter) considering that I only want to host one or two VM''s? Eric Pretorious Truckee, CA _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Hi, from my grub.conf file: module /vmlinuz-2.6.18-274.7.1.el5xen ro root=LABEL=/ nodmraid dom0_mem=512M pci=nomsi I have heard talk of 256M but have not tried it yet. Regards, Randy> > --- Original message --- > Subject: [Xen-users] GRUB boot parameters: dom0_mem > From: Eric <epretorious@yahoo.com> > To: xen-users@lists.xen.org <xen-users@lists.xen.org> > Date: Thursday, 21/06/2012 11:35 AM > > > > > I''ve installed Xen Hypervisor 3.0.3 (CentOS 5.7, i386) inside > Virtualbox 4.1.16 (Mageia 1, i686) and have noticed that Dom0 is > consuming 85% of the memory allocated to the VM (1GB) so I''d like to > reduce this as much as possible in order to make more room for one or > two VM''s. > > Is there a minimum amount of vRAM that can/should be allocated to Dom0 > (using the dom0_mem boot parameter) considering that I only want to > host one or two VM''s? > > Eric Pretorious > Truckee, CA > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xen.org > http://lists.xen.org/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
El 20/06/2012 11:33 p.m., Eric escribió:> Is there a minimum amount of vRAM that can/should be allocated to Dom0 > (using the dom0_mem boot parameter) considering that I only want to host > one or two VM''s?The minimum amount or RAM I have given to Dom0 (Debian Etch? really small footprint) in Xen 3.0 times was 256M. The system was quite usable. Then raised it to 384MB, it allowed me to consider "let''s say the hypervisor itself and Dom0 are consuming .5Gb of RAM, the rest can be dedicated to VMs". Today I give Dom0 768MB of RAM, but the people in internets usually suggests to give it at least 2GB. For reference, a typical RAM consumption for a just booted PV guest with 64-bit Debian Squeeze system, minimal installation (naked system with sshd) is around 100-120MB. Boots in less then 10 seconds.
From: Alexandre Kouznetsov <alk@ondore.com>>To: xen-users@lists.xen.org >Sent: Wednesday, June 20, 2012 10:09 PM >Subject: Re: [Xen-users] GRUB boot parameters: dom0_mem > >El 20/06/2012 11:33 p.m., Eric escribió: >> Is there a minimum amount of vRAM that can/should be allocated to Dom0 >> (using the dom0_mem boot parameter) considering that I only want to host >> one or two VM''s? >The minimum amount or RAM I have given to Dom0 (Debian Etch? really small footprint) in Xen 3.0 times was 256M. The system was quite usable. Then raised it to 384MB, it allowed me to consider "let''s say the hypervisor itself and Dom0 are consuming .5Gb of RAM, the rest can be dedicated to VMs". > >Today I give Dom0 768MB of RAM, but the people in internets usually suggests to give it at least 2GB. > >For reference, a typical RAM consumption for a just booted PV guest with 64-bit Debian Squeeze system, minimal installation (naked system with sshd) is around 100-120MB. Boots in less then 10 seconds. >Thanks, Alexandre: The Supermicro P8SC8/P8SCi motherboards in my test lab all have 4GB. However, only 3.1 GB is available so I''m trying to minimize the footprint of all the domains as much as possible. Eric Pretorious Truckee, CA _______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Thanks, Randy: I tried that boot parameter in both my nested environment and on my baremetal hypervisor (below) and did not see any change. [eric@xen2 ~]$ sudo cat /boot/grub/menu.lst ... title CentOS (2.6.18-274.el5xen) root (hd0,0) kernel /xen.gz-2.6.18-274.el5 module /vmlinuz-2.6.18-274.el5xen ro root=LABEL=/ dom0_mem=512M module /initrd-2.6.18-274.el5xen.img [eric@xen2 ~]$ cat /proc/cmdline ro root=LABEL=/ dom0_mem=512M Might I have overlooked something? Eric Pretorious Truckee, CA>________________________________ > From: Randy Katz <rkatz@simplicityhosting.com> >To: Eric <epretorious@yahoo.com> >Cc: xen-users@lists.xen.org >Sent: Wednesday, June 20, 2012 9:41 PM >Subject: Re: [Xen-users] GRUB boot parameters: dom0_mem > > > >Hi, > >from my grub.conf file: > >module /vmlinuz-2.6.18-274.7.1.el5xen ro root=LABEL=/ nodmraid dom0_mem=512M pci=nomsi > >I have heard talk of 256M but have not tried it yet. > >Regards, >Randy > > > >--- Original message --- >>Subject: [Xen-users] GRUB boot parameters: dom0_mem >>From: Eric <epretorious@yahoo.com> >>To: xen-users@lists.xen.org <xen-users@lists.xen.org> >>Date: Thursday, 21/06/2012 11:35 AM >> >> >>I''ve installed Xen Hypervisor 3.0.3 (CentOS 5.7, i386) inside Virtualbox 4.1.16 (Mageia 1, i686) and have noticed that Dom0 is consuming 85% of the memory allocated to the VM (1GB) so I''d like to reduce this as much as possible in order to make more room for one or two VM''s. >> >> >>Is there a minimum amount of vRAM that can/should be allocated to Dom0 (using the dom0_mem boot parameter) considering that I only want to host one or two VM''s? >> >> >>Eric Pretorious >>Truckee, CA >>_______________________________________________ >>Xen-users mailing list >>Xen-users@lists.xen.org >>http://lists.xen.org/xen-users >> > >_______________________________________________ >Xen-users mailing list >Xen-users@lists.xen.org >http://lists.xen.org/xen-users > >_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Thanks, Everybody: This question has already been addressed on this list and Faraj gave a very complete answer that differs slightly... It''s not mandatory to have that parameter, but it''s considered best practice. When ommitted, dom0 will use all available memory and ballon-down as needed when domUs are started. Depending on what you have running on dom0, ballooning down MIGHT cause a problem. So if you know (for example) that you have 4G memory, 512M will be allocated to dom0 while the reset will be used for domUs, you should set something like kernel /xen.gz-3.3.1 dom0_mem=512M on grub.conf, and have this entry on /etc/xen/xend-config.sxp (dom0-min-mem 512) These will effectively prevents dom0 from ballooning down memory. I verified that relocating the dom0_mem parameter to the top line (i.e., kernel /xen.gz...) fixed the problem. I apologize for duplicating the topic and, in the future, will search the archives first. ;) Eric Pretorious Truckee, CA>________________________________ > From: Eric <epretorious@yahoo.com> >To: Randy Katz <rkatz@simplicityhosting.com> >Cc: "xen-users@lists.xen.org" <xen-users@lists.xen.org> >Sent: Wednesday, June 20, 2012 10:48 PM >Subject: Re: [Xen-users] GRUB boot parameters: dom0_mem > > >Thanks, Randy: > >I tried that boot parameter in both my nested environment and on my baremetal hypervisor (below) and did not see any change. > > >[eric@xen2 ~]$ sudo cat /boot/grub/menu.lst >... >title CentOS (2.6.18-274.el5xen) > root (hd0,0) > kernel /xen.gz-2.6.18-274.el5 > module /vmlinuz-2.6.18-274.el5xen ro root=LABEL=/ dom0_mem=512M > module /initrd-2.6.18-274.el5xen.img > > > >[eric@xen2 ~]$ cat /proc/cmdline >ro root=LABEL=/ dom0_mem=512M > > > >Might I have overlooked something? > > >Eric Pretorious >Truckee, CA > > > > >>________________________________ >> From: Randy Katz <rkatz@simplicityhosting.com> >>To: Eric <epretorious@yahoo.com> >>Cc: xen-users@lists.xen.org >>Sent: Wednesday, June 20, 2012 9:41 PM >>Subject: Re: [Xen-users] GRUB boot parameters: dom0_mem >> >> >> >>Hi, >> >>from my grub.conf file: >> >>module /vmlinuz-2.6.18-274.7.1.el5xen ro root=LABEL=/ nodmraid dom0_mem=512M pci=nomsi >> >>I have heard talk of 256M but have not tried it yet. >> >>Regards, >>Randy >> >> >> >>--- Original message --- >>>Subject: [Xen-users] GRUB boot parameters: dom0_mem >>>From: Eric <epretorious@yahoo.com> >>>To: xen-users@lists.xen.org <xen-users@lists.xen.org> >>>Date: Thursday, 21/06/2012 11:35 AM >>> >>> >>>I''ve installed Xen Hypervisor 3.0.3 (CentOS 5.7, i386) inside Virtualbox 4.1.16 (Mageia 1, i686) and have noticed that Dom0 is consuming 85% of the memory allocated to the VM (1GB) so I''d like to reduce this as much as possible in order to make more room for one or two VM''s. >>> >>> >>>Is there a minimum amount of vRAM that can/should be allocated to Dom0 (using the dom0_mem boot parameter) considering that I only want to host one or two VM''s? >>> >>> >>>Eric Pretorious >>>Truckee, CA >>>_______________________________________________ >>>Xen-users mailing list >>>Xen-users@lists.xen.org >>>http://lists.xen.org/xen-users >>> >> >>_______________________________________________ >>Xen-users mailing list >>Xen-users@lists.xen.org >>http://lists.xen.org/xen-users >> >> >_______________________________________________ >Xen-users mailing list >Xen-users@lists.xen.org >http://lists.xen.org/xen-users > >_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
Hello. I would expect a 64-bit hypervisor to be able to see all 4GB, even if Dom0 is a 32-bit system. Ask xentop, how much ram it sees. Eric <epretorious@yahoo.com> wrote:> > >From: Alexandre Kouznetsov <alk@ondore.com> >>To: xen-users@lists.xen.org >>Sent: Wednesday, June 20, 2012 10:09 PM >>Subject: Re: [Xen-users] GRUB boot parameters: dom0_mem >> >>El 20/06/2012 11:33 p.m., Eric escribió: >>> Is there a minimum amount of vRAM that can/should be allocated to Dom0 >>> (using the dom0_mem boot parameter) considering that I only want to host >>> one or two VM's? >>The minimum amount or RAM I have given to Dom0 (Debian Etch? really small footprint) in Xen 3.0 times was 256M. The system was quite usable. Then raised it to 384MB, it allowed me to consider "let's say the hypervisor itself and Dom0 are consuming .5Gb of RAM, the rest can be dedicated to VMs". >> >>Today I give Dom0 768MB of RAM, but the people in internets usually suggests to give it at least 2GB. >> >>For reference, a typical RAM consumption for a just booted PV guest with 64-bit Debian Squeeze system, minimal installation (naked system with sshd) is around 100-120MB. Boots in less then 10 seconds. >> >Thanks, Alexandre: > >The Supermicro P8SC8/P8SCi motherboards in my test lab all have 4GB. However, only 3.1 GB is available so I'm trying to minimize the footprint of all the domains as much as possible. > >Eric Pretorious >Truckee, CA_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users
You are puting dom0_mem in a wrong place. It's a parameter for hypervisor, not for Dom0 kernel. Eric <epretorious@yahoo.com> wrote:>Thanks, Randy: > >I tried that boot parameter in both my nested environment and on my baremetal hypervisor (below) and did not see any change. > >[eric@xen2 ~]$ sudo cat /boot/grub/menu.lst >... >title CentOS (2.6.18-274.el5xen) > root (hd0,0) > kernel /xen.gz-2.6.18-274.el5 > module /vmlinuz-2.6.18-274.el5xen ro root=LABEL=/ dom0_mem=512M > module /initrd-2.6.18-274.el5xen.img > > >[eric@xen2 ~]$ cat /proc/cmdline >ro root=LABEL=/ dom0_mem=512M > > >Might I have overlooked something? > >Eric Pretorious >Truckee, CA > > > > >>________________________________ >> From: Randy Katz <rkatz@simplicityhosting.com> >>To: Eric <epretorious@yahoo.com> >>Cc: xen-users@lists.xen.org >>Sent: Wednesday, June 20, 2012 9:41 PM >>Subject: Re: [Xen-users] GRUB boot parameters: dom0_mem >> >> >> >>Hi, >> >>from my grub.conf file: >> >>module /vmlinuz-2.6.18-274.7.1.el5xen ro root=LABEL=/ nodmraid dom0_mem=512M pci=nomsi >> >>I have heard talk of 256M but have not tried it yet. >> >>Regards, >>Randy >> >> >> >>--- Original message --- >>>Subject: [Xen-users] GRUB boot parameters: dom0_mem >>>From: Eric <epretorious@yahoo.com> >>>To: xen-users@lists.xen.org <xen-users@lists.xen.org> >>>Date: Thursday, 21/06/2012 11:35 AM >>> >>> >>>I've installed Xen Hypervisor 3.0.3 (CentOS 5.7, i386) inside Virtualbox 4.1.16 (Mageia 1, i686) and have noticed that Dom0 is consuming 85% of the memory allocated to the VM (1GB) so I'd like to reduce this as much as possible in order to make more room for one or two VM's. >>> >>> >>>Is there a minimum amount of vRAM that can/should be allocated to Dom0 (using the dom0_mem boot parameter) considering that I only want to host one or two VM's? >>> >>> >>>Eric Pretorious >>>Truckee, CA >>>_______________________________________________ >>>Xen-users mailing list >>>Xen-users@lists.xen.org >>>http://lists.xen.org/xen-users >>> >> >>_______________________________________________ >>Xen-users mailing list >>Xen-users@lists.xen.org >>http://lists.xen.org/xen-users >> >> >_______________________________________________ >Xen-users mailing list >Xen-users@lists.xen.org >http://lists.xen.org/xen-users_______________________________________________ Xen-users mailing list Xen-users@lists.xen.org http://lists.xen.org/xen-users