Forum OpenACS Q&A: Re: OpenACS on Debian pros and cons...
OpenBSD is the easiest to secure, FreeBSD has more capabilities than OpenBSD in terms of ports and will support slightly more hardware - they are faster at supporting new stuff.
I have run OpenACS on Linux in the past and not been impressed.
However, I recently loaded Debian 3.0r1 on a new system, and put everything on an XFS partition (XFS is a journaled filesystem from SGI); and the performance increase can not be denied; most likely due to Linux caching everything it can up to the amount of RAM it has (OpenBSD has a fixed amount you can change at boot time for use in caching). It was easy to install as well.
I have not done any stringent performance tests, but running Postgres on XFS seems to speed up vacuums and other tasks.
Oh yeah, if it was up to me, I'd use Debian for everything, barring some much more compelling reasons than "Oracle Corp. says to use Red Hat". Like say, running Linux on an embedded microcontroller that's just too small for Debian, that sort of thing. :)
Of course, if you have multiple systems you would only do this once and then move the files over.
You would not lose data or configuration information, but would have to reboot.
Here's what Tom Lane had to say about the issue:
"Journaling metadata is good. Journaling file contents is redundant --- turn that off if you can. (Of course, if there is anything other than Postgres files on the same device, you may not want to turn off contents journalling..."
For ext3 that means mounting the /var/lib/postgres (or wherever your postgres data is stores) with the option "data=writeback".
I've only heard great things about SGI's XFS, especially its superb ACL features.
Postgres runs like a charm on all of my BSD machines, and I had very little trouble setting up OpenACS (aside from the known little patches to get a few models compile). This, unfortunately, may change with AOL Server 4 -- the stock distribution does not compile at all -- there seems to be just too much Linux-ism (no flames, please) in it (NB: fi your experience differs -- please let me know. I think I saw a few posts mentioning AS4 on OSX which is FreeBSD with Mach kernel).
FreeBSD does not have journaled FS, but it has a feature that maybe better in some circumstanese -- soft updates. I am not sure, however, how it affects Postgres -- never benchmarked it nor seen any benchmarks on it.