Scott Dowdle wrote:
Greetings,
I see these problems with Xen... and many people are stating that they are running CentOS on CentOS... ie Linux on Linux virtualization... so I thought I'd pipe up and mention OpenVZ again. It does Linux on Linux virtualization well and allows for i386 guests on x86_64 hosts just fine.
On a dual quad-core Xeon with 16GB of RAM (4GB of swap) I asked the vzsplit command how many machines it thinks my hardware is capable of. Here's the output:
[root@comp2 ~]# vzsplit -n 9999999 On node with 20114 Mb of memory (RAM + swap) 9999999 VEs can not be allocated The maximum allowed value is 3795
On a machine with 2GB of RAM and 4GB of swap:
[root@backup1 root]# vzsplit -n 9999999 On node with 6119 Mb of memory (RAM + swap) 999999 VEs can not be allocated The maximum allowed value is 639
Of course, there are some situations where OpenVZ (ie OS Virtualization) isn't suitable... but for the vast majority of common server tasks, it is. I don't claim you should try that many virtual machines on a single host node but it just goes to show you the density differences possible between Xen and OpenVZ, eh? :)
TYL,
It would really suck to have 3795 "virtual machines" die all at the same time from a single kernel panic.