SystemTap (the kernel probing tool build into Linux) is coming along pretty well - I needed to create something to alert me when arbitrary apps set TCP_NODELAY last week, spend a little while looking at SystemTap, made a simple script that probes at tcp.setsockopt(), got the info I needed, and printed it presentably.

I added the script to http://sourceware.org/systemtap/wiki/WarStories . Check it out and others, it's pretty easy to pick up.

SystemTap is great for general system issues, but isn't nearly as good when trying to look at issues that occur inside the JVM.

PS. Check out http://fedoraproject.org/wiki/Features/SystemtapStaticProbes for info on current Java status (which seems to be more developed than we think).

True. I believe they're adding providers to the major VMs though (I mainly work in Python so I focus on the cPython VM, but I have heard of some early JVM introspection work too).

Yup, DTrace and ZFS are pretty much the only things Solaris brings to the table above what Linux offers.

Interestingly I've never come across any pure Solaris shops that run ZFS, I suppose because if you're conservative enough only to use Solaris, you're too conservative to trust ZFS.

Zones too. I think they offer more then what the usual jail does. Never really used both of them, but.. yeah, zones sound nice, too :)

Also, solaris is probably the most stable OS i've ever worked with.

Solaris zones are awful, and a good example of where Linux is far superior to Solaris. The creators of Zones seemed to have user-mode-Linux as their model, and it shares most of the annoyances of that too. It's not virtualization, and it's not a jail - it's a middle ground which is good for neither.

Agree with you to some extent on stability - I've seen Solaris boxes with a load of 300+ still up and running although unusably slow, where Linux would almost certainly have died from resource starvation. In general use, both Linux and Solaris are pretty damn reliable though.

Whats so bad about zones? It's clear that they are no virtualization. As you said it's a middleground, more capable as jails but not virtual, which is fine if you don't need it?

I'd add SMF (unless you know about something similar that's built-in into Linux ?).

What does that get me over Upstart or the other event-driven init systems?

(This is a question of genuine curiosity. SMF has led to many headaches when I've had to deal with it, simply because it didn't seem to comply with normal conventions like returning nonzero for failure or actually printing what goes wrong to the console.)

EDIT: add trailing parenthesis.

XML based config files!

Just kidding.

DTrace and ZFS are both available on FreeBSD.

Call me a BSD bigot (even though I use Linux/OS X at work) but I really fail to see any rational reason to use Solaris at this point.

We have a Solaris database + filestore at work, mostly for Z-raid, but now that FreeBSD has ZFS, when it gets EOL'd (with a vicious grin on my face) it's going to be a BSD box that replaces it.

I'm sure you already know, but DTrace is in FreeBSD.