Low memory
One of the problems encountered is shortage of memory. Or better: a lack of free pages. The problem became clear yesterday, when trying to FTP a 500Kb file from Demeter (WindowsXP) to Diana (VMS). The connection reconnected – and reconnected — and kept reconnecting, while, running MONITOR on a telnet session, free pages dropped from about 16K to zero – in seconds. Even in this moment – where MySQL has done some work, and the PHP engine is happily started doing some work as well (and it will be triggered once in a while to get this text saved while not yet commited), it has dropped from 12K to 1.5. A massive 10K pages in use (I have MONITOR running).
The next two images show the memory usage and paging yesterday, when I did the FTP connection at approximately 21:00 (All times GMT)
The blue line is pagefile usage – and I have a massive 3GB online. Being used for about 75% at some point – guess what THAT would have caused if I had my previous 1Gb file….
It has been so bad, that HyperSpy (the monitor that allows web-based monitoring) didn’t get trhough at some pint – that explains the gap in the memory graph.
What I don’t understand: I reversed the changes I made to accomodate Distributed Netbeans and Webes. Before these changes, there wasn’t really a perfomance issue. At least, I never ran into it. But it’s well possible I overlooked something. Another weird thing: I uploaded a complete set of photograhs and pages this weekend, all in all about 22M – 40 times as much – but that went nice and smooth. The only difference: that was over a 100Mb LAN, not over a 54Mb Wireless access point )on the same network).
He who understands, please explain…
First things first.
MODPARAMS.DAT still contained settings for Advanced Server, that I never got to work, so it was never really installed after I upgraded the system, so I got rid of these settings. Some othter things need to be addressed as well, 256 Gb should be way enough – and I don’t plan to use Java again, on Diana anyway.
So I lurked on the HP site for performance documentation – and the manual on the 8.3 set is VMS 7.3. But I guess most is still valid.
That means: back to the drawing board and calculator, to get at least a somewhat better free list. Having some processes swapped – no big deal if these aren’t heavily used :(. It’s been quite a while since my last tuning job. about 20 years, I reckon….(But that has been a much easier problem)
And of course: MySQL server just crashed again. Not enough core. I’ve seen it.