Thanks Ahmed for your reply. On Tue, Jul 28, 2009 at 7:16 PM, Ahmed Taha<consult.itlinux@xxxxxxxxx> wrote: > Hi, > > Dell PowerEdge is a good choice. I would go for the PowerEdge 2850 if I > could. For such a number of virtual machines (30), you will definitely need > not only high RAM but CPU power as well. First, let us consider the memory. > Each RHEL5 guest instance needs at least 512M (eventhough I have tested few > instances and I was able, with some tuning, to make it work down to 384M, > but definitely not 256M). The same min of 512M for Solaris10 will be > essential. Now for 30 VMs, you are talking about 15G of physical memory (not > including page cache and buffers). > Are you talking about fully virt VMs or Para Virt in this case? WIth Para Virt the allocation is dynamic. Isn't it? > For CPUs, theoretically, performance hit starts when the number of VCPUs > goes above the number of physical CPUs, but the exact nonlinear behavior has > a lot of debate about it. What I have actually tested is two AMD64 dual-core > (4 cpu's) while I was able to build up 18 VM's with one VCPU per each, > however, performance was very bad. I repeated the experiment on just one > Intel dual-core processor (2 cpu's) and I was able to build up to 10 VM's. > But once again, I could not run except 4 or 5 with a production-level > performance. So, you may scale accordingly for these 30 machines. I would go > for 4 dual-core or two quad-core at the least. If I understand correctly, to get a production level performance even with 2 quad core, I can run only around 8 virtual machines? > > Don't forget dom0 may be picky about how much memory it gets, specially if > you will run X. Check the forums for further discussions if you encountered > X issues when xend starts. > > Hope this helps, > Thanks ! Paras. > > > On Fri, Jul 24, 2009 at 5:54 PM, Paras pradhan <pradhanparas@xxxxxxxxx> > wrote: >> >> hi, >> >> I will be creating a cluster using red hat EL 5.3 consisting of 3 >> nodes which will run Xen virtual machines. The first two nodes will >> host around 30 virtual machines ( all paravirt Linux and some Solaris >> if possible) . The third node will be basically a fail over node and >> will host virtual machines if there is a problem at node 1 or node 2. >> I do not know if this is the right way to ask but I need >> recommendation on which CPU to choose (i7, phenom, quad core or dual >> core) and how much RAM do I need on node 1 and node 2 and on also node >> 3. And also which server hardware is recommended for my purpose. My >> test cluster is based on Dell Poweredge 1800 machines with DRAC 4 >> (which I am using for fencing) and looks like DELL Poweregde server >> can be a good candidate. >> >> Any help is highly appreciated. >> Thanks >> Paras. >> >> -- >> Linux-cluster mailing list >> Linux-cluster@xxxxxxxxxx >> https://www.redhat.com/mailman/listinfo/linux-cluster > > > > -- > Ahmed G. Taha > Linux Systems Consultant RHCE & > Operating System Programmer > (Cell): (573) 289-7300 > > -- > Linux-cluster mailing list > Linux-cluster@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/linux-cluster > -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
