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[aprssig] Re: More on the findU server issue...

scott at opentrac.org scott at opentrac.org
Sun Sep 25 20:36:51 UTC 2005


> Load balancing works when the problem is the web load, but 
> that is not the case here. The problem is the database, with 
> a constant (dozern of packets a second) write pressure on the 
> database means you need a fast disk array. If you tried to 
> load-balance with findU, you need a server for every 2 or 
> three simultaneous requests if you use hard at the level of 
> the current backup server.

I was assuming that each machine could run its own database.  I'm pretty
sure I could tune an Oracle database to do pretty well with that load on
modest hardware (I've had one logging large chunks of the APRS IS stream,
but never the whole thing), but that doesn't help you much either.  I don't
know enough about MySQL to know how you might improve the write performance.
For writes alone, raw disk throughput shouldn't be that much - I get about 2
kB/sec from the IS stream, and even assuming a 100x increase to account for
db overhead and indexes, that's only 200 kB/sec.  My cheap ATA drives
benchmark in the tens of megabytes/sec.  Is MySQL really that bad with heavy
writes?  Or is it the concurrent read/write load that kills it?  What's the
cache hit percentage on reads?

> My opinions on open source are described on the findU site, 
> no need to restart the argument here. For five and a half 

Not arguing, you have every right to keep the code to yourself.  You're
keeping the code because of potential commercial value, and I'm more than
willing to contritube on a commercial basis through advertising.  Again,
it's just a personal philosophy thing.

Scott
N1VG







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