i wish to buil something but im confused whit 2 option
option 1 : im runing apache, mysql, ftp, in a single machine and 1 os (NO VM)
option 2 : im make each server for example apache, mysql at one Virtual machine. so apache server have 1 Vm, Mysql server have 1 VM to.
but im have only 1 phisical machine.
where's more powerfull option one or two?
Most likely option 1, since option 2 involves communicting between VMs which quite a bit of overhead.
I've an alternative choice: 1VM on 1 Physical machines. All application run within this VM.
There's some overhead by virtualization. But AFAI, xen's overhead is very small. I really do that on my small site http://fclose.com/ which runs on the top of old PC with 1G memory. This PC possess the webserver on a single VM and ssh server on another VM and also the domain0 also can serve as my desktop for browsing web page, printing etc. (obviously, no large job).
The advantages is simpler management and backup. I simply shutdown the VM, backup the VM's image or LVM partition after which start the VM again. You can do this instantly by cron with scripts. We only have to cope with one image file a treadmill partition. The task is a lot more compact although we want more disk space.