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On Fri, 16 Dec 2005, Jan Klopper wrote:
One of my major problems though is that my nodes only have 265mb ram, and the
new sun only comes with 512mb ram.
While ram is cheap i hesitate to actually go out and buy a couple of gb's
since the machines are rather picky being compaq's.
Would the low amount of ram give me any problems?
And would it make sense to give each node a massive hdd swap partition?
I reccon giving each node a 5gb hdd swap would pretty much mean to keep a
local version of the NFS server's data on there local disk thus improving
performance, while automatically staying up to date, and automatically
flushing files not needed anymore.
Pages that are in the realserver's memory are available
with a latency of 10ns.
Pages in local swap have a latency of 10ms (10^6 more than
memory).
Pages pulled out of the database have the latency of
generating the page and shipping it across the network
to the realserver (several seconds?).
then you have latency across your network to the client.
If all your pages are being pulled out of the database, then
no amount of memory on your realservers is going to help.
If you have say 200M of pages that are accessed all the time
with the other 12G rarely accessed, then memory will help,
as long as your connection to the client is low latency.
If you have 5G of pages that are accessed all the time and
the other 7G rarely, then 5G of swap will give you 5G of
pages with a latency of 10ms.
Do the pages have expiry notices so that the client has to
fetch them from the database (rather than swap/memory of
the realserver) when they shift-click?
Joe
--
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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Homepage http://www.austintek.com/ It's GNU/Linux!
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