I've recently spent some time thinking about virtualization technology,in particular how I feel about Xen versus VMware. In theory the choiceshould be a slamdunk for me, because VMware requires evil binary kernelmodules and I have usually avoided that sort of thing even when it wassomewhat painful (eg, I don't use ATI's binary X drivers). In practice,though, I am only distantly lukewarm on Xen and much more interested inVMware.

The simple summary why this is is that Xen is

Presented in illustrated form, on at least Solaris 8, FreeBSD, andOpenBSD:

$ exec 9>/dev/null$ exec 10>/dev/nullexec: 10: not found

(And the shell exits.)

The genuine Bourne shell only allows redirection to (or from)single-digit file descriptors; if you give multiple digits, itinstead gets parsed as ' exec 10 >/dev/null '.

(The limitation has been faithfully copied by at least some Bourne shell

We have historically had a small problem with our inetd s: every sooften when we attempted to restart it with a SIGHUP to make it pick up aconfiguration change, it would fail to bring up an important UDP-basedservice we need, reporting a failure to bind to the UDP port.

(We saw the same problem with xinetd ; I'm using ' inetd ' as as ageneric term.)

What was probably happening is that when this would happen, inetd hadjust spawned the program to handle