Marius Bjørnstad's questions

When the controller's battery-backed write cache is disabled, but the drive's write caches are enabled, will the controller pass on the flush commands from the OS to the drives (all physical drives in RAID0 or RAID1 virtual drives)?

The reason I ask is that the performance is much better with the drive caches enabled. It's even much better than with drive caches off and controller's cache on. If it is able to flush the caches on demand, then there shouldn't (in theory) be any filesystem corruption on power loss, with modern OSes and filesystems. [I realise there's a real risk of bugs, but power cuts are extremely rare where I am, so it may be worth the risk if it at least works on paper.]

If the answer is that it depends on the controller: I'm using MegaRaid 9280. Single disk RAID0s. Or is there any way to test this reliably?

I would like to run an application based on the Tornado web server in a production environment. The performance requirements are low.

Since I don't need a load balancer, I wonder if it is OK to have it directly accessible on ports 80 and 443. Is this OK from a security perspective, and are there are other problems? This is of course, assuming I find some way to run it as a non-root user (authbind not available on RHEL).