On 2/23/07, Tom Duerbusch <[EMAIL PROTECTED]> wrote:
In a memory constrained system, it may be better (definitely for test/development systems) to have swap go to dasd. Then, you are only impacting that machine. When you have a big impact on the paging system, almost everyone (including production) can be impacted.
I claim that "Linux swap to real DASD is good for one thing, and that's to slow them down" From your post I understand that is your approach to tuning. The sad part is that you slow them down all the time when they swap, also when enough resources available. To avoid that, you need to make the servers large enough that they normally don't swap... and so you become more memory constrained. <img src=death-spiral.gif>
Actually, Mark, we agree on the basics of vdisk/swap. But I have never seen a paging system that couldn't be swamped. How many times have I PEEKed a file, should have been 10,000 lines, but it was 1,000,000 lines (or 10 million lines), and watch the paging system, deal with my error.
If you really measured that your paging subsystem was holding you back there, then you should probably improve that. Properly configured, z/VM can page pretty heavy without hurting itself. Very likely that it was the spooling subsystem that held you back because we sip slowly on spool files. Rob -- Rob van der Heij Velocity Software, Inc http://velocitysoftware.com/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
