yet another sd_max_throttle question
From: Booth, David CWT-MSP (dbooth_at_carlson.com)
Date: 01/27/04
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Date: Tue, 27 Jan 2004 15:48:33 -0600 To: sunmanagers@sunmanagers.org
I know this parameter has been discussed before at length on this list
and elsewhere but I've read everything I can find and still dont have
much of a comfort level with picking a number to use...
I'm connecting a bunch of EX500 systems to a StorageTek D280 array via
Nishan switches. All of these systems have a pair of JNI FC64-1063
HBAs (yes I know they are older HBAs, these are older servers and we
dont want to buy new SBus HBAs because we are not going to be buying
any more SBus server hardware) and we had no problems hooking these up
to an XP256 via Brocade switches with sd_max_throttle set to its
default of 256. Hooking some test servers up to the D280 we ended up
with a lot of scsi transport errors so I set the throttle on the test
servers down to 6. It reduced the frequency but didnt eliminate it.
Other than the SAN hardware differences its notable that in the new
setup the servers are all going to be using a much smaller group of
LUNs, a maximum of 40 for our largest configuration as opposed to a
maximum of 98 with the old setup. This confused me somewhat because I
was under the impression that fewer LUNs reduced the need for
throttling rather than increasing it. I'm a little worried because I
cant do a full-up test of our production configuration since we only
have one system capable of carrying full production database loads and
thats the live one, a 12-CPU E4500.
Does anyone know of a comprehensive in-depth resource where I can find
details of which factors impact the need for throttling and how,
exactly how the throttling is imposed and how it appears to the
userland apps when it kicks in, also how to find some indication of
what the performance impact will be of setting it either too high or
lower than it needs to be. I'm not asking you to spend your valuable
time doing my config for me, I simply need pointing to the information
I need to work it out myself...
-- Dave Booth dbooth@carlson.com +----------------------------------------------------------------+ | Trouble rather the tiger in his lair than the sage amongst his | | books, for to you kingdoms and their armies are things mighty | | and enduring but to him they are the toys of the moment, to be | | overturned by the flicking of a finger. | +----------------------------------------------------------------+ _______________________________________________ sunmanagers mailing list sunmanagers@sunmanagers.org http://www.sunmanagers.org/mailman/listinfo/sunmanagers
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