[Opensim-users] MySQL on seperate server?

[Tedd Hansen]

Hi

Just sharing info; no intent at OS/religious discussion... Recently had the same discussion with a friend where the defrag problem came up. :)
But the issue is relevant to performance.

(I'm by the way running OpenSim on my preferred OpenSim platform which is Linux Debian 5/Lenny, with OpenSim init.d-script and the works.)

Linux did have an offline defrag utility for ext2/ext3. But at least Debian seems to have dropped it due to incompatibility with new features in ext3:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=396449
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=446691
Searching for it I did however come over a LOT of misconceptions on how (Windows) filesystems work. :)
All filesystems get fragmented over time (deleting small files now and then and having OS choose large free spaces for new files will eventually use up all large free blocks), and get quickly fragmented when the disk is nearing full. So for any system keep 10-20-30% free space at all times. Background online defrag is the best way to combat this when after it has occurred. Windows and Mac (iirc) do online background defrag, and also align frequently used files for faster startup/access.

So to conclude: If you don't drop below say 10% free space there is no need for defragmenting. And the cp-command is the best Linux defragmenter atm. :)


Another thing thing to note is that the performance for .Net is higher under Windows (MS) that Linux (Mono). I guess because Mono have focus on extending its features, and not so much on optimizing (yet). Make it work, make it stable, make it fast. How much difference I guess depends on the normal set of unlimited undeterminable variables. I've tried to compile OpenSim under Windows and run the .exe under Linux with varying results. Some unexplained crashes that disappeared with a recompile in Linux.

But in my opinion the cost of a few extra MHz in the CPU (or extra cores) is so low that it doesn't matter that much if Mono doesn't outperform MS. It is more important to me that it's easy to administer. BASH, Perl, VIM ffs. :)

BR,
 Tedd

-----Original Message-----
From: opensim-users-bounces at lists.berlios.de [mailto:opensim-users-bounces at lists.berlios.de] On Behalf Of Karen Palen
Sent: 18. februar 2010 22:39
To: opensim-users at lists.berlios.de
Subject: Re: [Opensim-users] MySQL on seperate server?

Hi,

I was deliberately being as neutral as I could in my tone since I do NOT want to start some "Fanboy" flamewar!

I do notice that a defrag operation is standard in all Windows versions and certainly does make a huge difference in file access.

I also take note that "defrag" is NOT a Linux utility and I have not experienced as problem due to its lack. My only real experience for potential fragmentation was in copying/moving a Ubuntu 9.04 install to another machine - about the crudest form of "defrag" there is!

I was careful to use a "file by file" copy and not "sector by sector" for exactly this reason. The old file system had been in heavy use for nearly a year, but I measured zero difference in hard drive performance!