Hello, I know the parameter mem-max sets the maximum RAM that can be allocated to a domU. Beside this limit, VM has to be recreated with required memory size. Is it possible to set the mem-max parameter without recreating VM? xm max-mem seems to work but in fact, has no effect (at least on my debian Lenny dom0) If not possible to dynamicly change max-mem, Is it possible/safe/clever to set max-mem to the maximum amount of RAM the dom0 can allocate (total RAM - minimum dom0 RAM). Thanks. -- <http://www.horoa.net> _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 19/07/2011 17:50, Alexandre Chapellon wrote:> Hello, > > I know the parameter mem-max sets the maximum RAM that can be allocated > to a domU. > Beside this limit, VM has to be recreated with required memory size. > > Is it possible to set the mem-max parameter without recreating VM? > xm max-mem seems to work but in fact, has no effect (at least on my > debian Lenny dom0) > > If not possible to dynamicly change max-mem, Is it possible/safe/clever > to set max-mem to the maximum amount of RAM the dom0 can allocate (total > RAM - minimum dom0 RAM). > > Thanks.If you are going to be using these DomUs for anything even remotely serious, then I would strongly advise against dynamically resizing a Linux environment''s available memory. Form personal experience, I can categorically say that this leads to a very unstable system. Just my 2 pence Thanks _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
2011/7/19 Alexandre Chapellon <a.chapellon@horoa.net>> Hello, > > I know the parameter mem-max sets the maximum RAM that can be allocated to > a domU. > Beside this limit, VM has to be recreated with required memory size. > > Is it possible to set the mem-max parameter without recreating VM? > xm max-mem seems to work but in fact, has no effect (at least on my debian > Lenny dom0) >I confirm. In XEN 4.0 on squeeze - no effect too.> > If not possible to dynamicly change max-mem, Is it possible/safe/clever to > set max-mem to the maximum amount of RAM the dom0 can allocate (total RAM - > minimum dom0 RAM). > > Thanks. > > -- > <http://www.horoa.net> > > _______________________________________________ > 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
Le 19/07/2011 19:05, Jonathan Tripathy a écrit :> > On 19/07/2011 17:50, Alexandre Chapellon wrote: >> Hello, >> >> I know the parameter mem-max sets the maximum RAM that can be allocated >> to a domU. >> Beside this limit, VM has to be recreated with required memory size. >> >> Is it possible to set the mem-max parameter without recreating VM? >> xm max-mem seems to work but in fact, has no effect (at least on my >> debian Lenny dom0) >> >> If not possible to dynamicly change max-mem, Is it possible/safe/clever >> to set max-mem to the maximum amount of RAM the dom0 can allocate (total >> RAM - minimum dom0 RAM). >> >> Thanks. > > If you are going to be using these DomUs for anything even remotely > serious, then I would strongly advise against dynamically resizing a > Linux environment''s available memory. Form personal experience, I can > categorically say that this leads to a very unstable system. > > Just my 2 pence >Even without keeping beside the memory-max? I remember Having done it too but it did not turn the system unstable AFAICT. Does anybody have similar feelings about playing with meme making Linux domU unstable? regards> Thanks > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users-- <http://www.horoa.net> _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
>> >> If you are going to be using these DomUs for anything even remotely >> serious, then I would strongly advise against dynamically resizing a >> Linux environment''s available memory. Form personal experience, I can >> categorically say that this leads to a very unstable system. >> >> Just my 2 pence >> > Even without keeping beside the memory-max? I remember Having done it > too but it did not turn the system unstable AFAICT. > > Does anybody have similar feelings about playing with meme making Linux > domU unstable? >http://wiki.xensource.com/xenwiki/XenBestPractices Read the section "http://wiki.xensource.com/xenwiki/XenBestPractices". Even though that talks about Dom0, the same still applys for DomU as they run Linux too. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 21/07/2011 09:26, Jonathan Tripathy wrote:> >>> >>> If you are going to be using these DomUs for anything even remotely >>> serious, then I would strongly advise against dynamically resizing a >>> Linux environment''s available memory. Form personal experience, I can >>> categorically say that this leads to a very unstable system. >>> >>> Just my 2 pence >>> >> Even without keeping beside the memory-max? I remember Having done it >> too but it did not turn the system unstable AFAICT. >> >> Does anybody have similar feelings about playing with meme making Linux >> domU unstable? >> > > http://wiki.xensource.com/xenwiki/XenBestPractices > > Read the section "http://wiki.xensource.com/xenwiki/XenBestPractices". > Even though that talks about Dom0, the same still applys for DomU as > they run Linux too.That should be "read section "Why should I dedicate fixed amount of memory for Xen dom0"" _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 07/21/2011 10:30 AM, Jonathan Tripathy wrote:> > On 21/07/2011 09:26, Jonathan Tripathy wrote: >> >>>> >>>> If you are going to be using these DomUs for anything even remotely >>>> serious, then I would strongly advise against dynamically resizing a >>>> Linux environment''s available memory. Form personal experience, I can >>>> categorically say that this leads to a very unstable system. >>>> >>>> Just my 2 pence >>>> >>> Even without keeping beside the memory-max? I remember Having done it >>> too but it did not turn the system unstable AFAICT. >>> >>> Does anybody have similar feelings about playing with meme making Linux >>> domU unstable?Not really. My Xen servers have 32GB of memory. I limit Dom0 memory to 2GB. I start all my DomU''s with ''maxmem=xxxx'' (where xxxx is what I consider to be ''enough'' in every possible scenario for that particular host). I also use ''mem=xxxxM'' kernel parameter for DomU kernels - maybe that''s deprecated now but in the past it was required for the DomU kernel to properly allocate memory.>> >> http://wiki.xensource.com/xenwiki/XenBestPractices >> >> Read the section "http://wiki.xensource.com/xenwiki/XenBestPractices". >> Even though that talks about Dom0, the same still applys for DomU as >> they run Linux too. > > That should be "read section "Why should I dedicate fixed amount of > memory for Xen dom0""To me the ability to dynamically reduce or increase DomU memory is one of the essentials of virtualization. Besides - I''ve been doing it for about 4-5 years now and wouldn''t say I noticed any related stability issues. IMHO the section of the XenBestPractices you mention it''s applicable to Dom0 only (as in you start with huge amount of memory, but eventually end up with just ''a bit'' anyway. It''s usually a different story with DomU''s - I like to start with not-so-much memory and add it when needed. D.> > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users-- Danilo Godec, sistemska podpora / system administration Predlog! Obiscite prenovljeno spletno stran www.agenda.si ODPRTA KODA IN LINUX STORITVE : POSLOVNE RESITVE : UPRAVLJANJE IT : INFRASTRUKTURA IT : IZOBRAZEVANJE : PROGRAMSKA OPREMA Visit our updated web page at www.agenda.si OPEN SOURCE AND LINUX SERVICES : BUSINESS SOLUTIONS : IT MANAGEMENT : IT INFRASTRUCTURE : TRAINING : SOFTWARE _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
thanks for all your answers. I should have asked my question in another way maybe: Is it a problem to have the sum of max-mem of all the domU being bigger than the total amount of RAM on the dom0? regards. Le 21/07/2011 13:37, Danilo Godec a écrit :> On 07/21/2011 10:30 AM, Jonathan Tripathy wrote: >> >> On 21/07/2011 09:26, Jonathan Tripathy wrote: >>> >>>>> >>>>> If you are going to be using these DomUs for anything even remotely >>>>> serious, then I would strongly advise against dynamically resizing a >>>>> Linux environment''s available memory. Form personal experience, I can >>>>> categorically say that this leads to a very unstable system. >>>>> >>>>> Just my 2 pence >>>>> >>>> Even without keeping beside the memory-max? I remember Having done it >>>> too but it did not turn the system unstable AFAICT. >>>> >>>> Does anybody have similar feelings about playing with meme making >>>> Linux >>>> domU unstable? > > Not really. > > My Xen servers have 32GB of memory. I limit Dom0 memory to 2GB. > > I start all my DomU''s with ''maxmem=xxxx'' (where xxxx is what I > consider to be ''enough'' in every possible scenario for that particular > host). I also use ''mem=xxxxM'' kernel parameter for DomU kernels - > maybe that''s deprecated now but in the past it was required for the > DomU kernel to properly allocate memory. > >>> >>> http://wiki.xensource.com/xenwiki/XenBestPractices >>> >>> Read the section "http://wiki.xensource.com/xenwiki/XenBestPractices". >>> Even though that talks about Dom0, the same still applys for DomU as >>> they run Linux too. >> >> That should be "read section "Why should I dedicate fixed amount of >> memory for Xen dom0"" > > To me the ability to dynamically reduce or increase DomU memory is one > of the essentials of virtualization. Besides - I''ve been doing it for > about 4-5 years now and wouldn''t say I noticed any related stability > issues. > > IMHO the section of the XenBestPractices you mention it''s applicable > to Dom0 only (as in you start with huge amount of memory, but > eventually end up with just ''a bit'' anyway. It''s usually a different > story with DomU''s - I like to start with not-so-much memory and add it > when needed. > > D. > > >> >> _______________________________________________ >> Xen-users mailing list >> Xen-users@lists.xensource.com >> http://lists.xensource.com/xen-users > >-- <http://www.horoa.net> _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Alexandre Chapellon wrote:>Is it a problem to have the sum of max-mem of all the domU being >bigger than the total amount of RAM on the dom0?I see no reason why it should be a problem. I''d have thought the main reason would be to allow for overprovisioning RAM and being able to adjust usage as required. -- Simon Hobson Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed author Gladys Hobson. Novels - poetry - short stories - ideal as Christmas stocking fillers. Some available as e-books. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
alxgomz wrote> ... I know the parameter mem-max sets the maximum RAM that can be > allocated > to a domU. > Beside this limit, VM has to be recreated with required memory size...Someone from virtualizor just told me recreate a VM in order to change the max memory size. That notion is nonsense. To change the max mem size, "power off" the VM so it is completely halted. Then you can manually edit the VMs configuration file at /etc/xem/auto. Keep in mind you should backup first and be very cautious editing the file. One change of the syntax can have costly affects. More Info: https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Virtualization/sect-Virtualization-Troubleshooting_Xen-Guest_configuration_files.html -- View this message in context: http://xen.1045712.n5.nabble.com/setting-max-memory-tp4612943p5712796.html Sent from the Xen - User mailing list archive at Nabble.com.