Hello,
We recently purchased a Dell PowerEdge 6650 thinking it would be a real fast
server.
Specs are:
OS: Linux Debian 4.0/Etch
RAID 5 on 4x U320 15k rpm drives
(uses a perc-raid 3/DC hardware raid controller)
16GB of RAM
4 3.0 Ghz Xeon processors - I think they're dual core, in /proc/cpuinfo it
shows up as 8 processors - maybe it's only HT
I first made the mistake of using the default kernel, which provides SMP
support but not large memory support.
I have the output of a mysql sql-bench run from mysql on a Mac Mini to compare
performance with.
The server was only 0.35 (relative) the speed of the Mac mini - that means an
8 core 3.0 Ghz Xeon server with 16GB of RAM was only about 3x as fast as a as
a single-core 1.25 Ghz G4 with 1GB of RAM (and a mini uses those
little "laptop" hard drives, too).
Needless to say my employer was shocked at the terrible performance and
decided to sell the 6650 right away.
But I can't help but wonder if there's not something terribly wrong with the
settings - either the OS or mysql settings.
I changed the kernel to the "-bigmem" kernel. It now sees all the RAM, but the
sql-bench output on this try was _exactly_ the same: 0.35
I copied the my-huge.cnf from the examples directory and changed the
thread_concurrency setting to 8 (because it said to set it to No. of CPUs*2).
I also set the tmpdir, basedir, datadir and language, which were set in the
original my.cnf
I ran sql-bench again and the performance was even worse this time: 0.36
Someone suggested I try the -amd64 kernels which provide 64 bit but when I try
to boot it I get various errors about "this CPU does not support long
(something) please use a 32-bit OS" - the 64 bit install CD says the same
message. So I assume these are not 64 bit CPUs.
Any idea how I can configure this server to maximize performace?
I think the multiple CPUs are a waste: I'm not looking for lots of
concurrency, I want 1 query done really fast.
Thanks.
JW
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System Administrator - Cedar Creek Software
http://www.cedarcreeksoftware.com
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