From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Robert Dunkley" Subject: RE: [Xen-users] Max. PV and HVM Guests Date: Mon, 9 Nov 2009 08:17:31 -0000 Message-ID: References: <1257685302.5339.11.camel@k2000.jpp.fr> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Return-path: Content-Class: urn:content-classes:message List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: jp.pozzi@izzop.net, "Mr. Teo En Ming (Zhang Enming)" Cc: xen-devel@lists.xensource.com, xen-users@lists.xensource.com List-Id: xen-devel@lists.xenproject.org There seems to also be a limit imposed by CPU context switching. Ie. = Once you have enough VMs trying to grab a cpu core things come to a = standstill as the cpu spends most of its time switching rather than = processing. The most common bottleneck I find is disk performance but = this depends hugely on what your VMs are doing. -----Original Message----- From: xen-users-bounces@lists.xensource.com = [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Moi meme Sent: 08 November 2009 13:02 To: Mr. Teo En Ming (Zhang Enming) Cc: xen-devel@lists.xensource.com; xen-users@lists.xensource.com Subject: Re: [Xen-users] Max. PV and HVM Guests Hello, The maximum is a direct function of the available memory, every new machine "eats" some memory and when there is no more memory ...... I had some servers (64bits, 2 quad core and 32Gb Ram) running 19 VM, 2003 server, 2000 Server,Fedora, Debian all in 32bits. In my own system I have tested with upto 10 VMs of 512M each without breaking the system. Regards JP Pozzi Le dimanche 08 novembre 2009 =C3=A0 19:45 +0800, Mr. Teo En Ming (Zhang Enming) a =C3=A9crit : > Hi, >=20 > I have observed that there is a maximum limit to the number of PV or > HVM virtual machines you can start before dom0 hangs or crashes. >=20 > For Fedora 11 Linux x86-64 PV guests, dom0 will crash when I start the > 7th instance. Max I can start is 6 without crashing. >=20 > For CentOS 5.2 Linux x86-64 HVM guests, dom0 will crash when I start > the 4th instance. Max I can start is 3 without crashing. >=20 > I have 6 GB of DDR2-800 with Intel Pentium Dual Core E6300 2.8 GHz on > Intel DQ45CB motherboard. >=20 > Are the above limits reasonable considering the hardware > specifications of my computer? >=20 > I am using Xen 3.5-unstable changeset 20143 with pv-ops dom0 kernels > 2.6.30-rc3, 2.6.31-rc6, 2.6.31.1, 2.6.31.4, and 2.6.31.5. My host > operating system is Fedora 11 Linux x86-64. >=20 > --=20 > Mr. Teo En Ming (Zhang Enming) Dip(Mechatronics) BEng(Hons)(Mechanical > Engineering) > Alma Maters: > (1) Singapore Polytechnic > (2) National University of Singapore > My Primary Blog: http://teo-en-ming-aka-zhang-enming.blogspot.com > My Secondary Blog: http://enmingteo.wordpress.com > My Youtube videos: http://www.youtube.com/user/enmingteo > Email: space.time.universe@gmail.com > Mobile Phone (Starhub Prepaid): +65-8369-2618 > Street: Bedok Reservoir Road > Country: Singapore > _______________________________________________ > 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 The SAQ Group Registered Office: 18 Chapel Street, Petersfield, Hampshire GU32 3DZ SAQ is the trading name of SEMTEC Limited. Registered in England & Wales Company Number: 06481952 http://www.saqnet.co.uk AS29219 SAQ Group Delivers high quality, honestly priced communication and I.T. = services to UK Business. Broadband : Domains : Email : Hosting : CoLo : Servers : Racks : Transit = : Backups : Managed Networks : Remote Support. ISPA Member