Today, Firefox on my iBook/G4 (with MacOS 10.4.10) started to swap and after consuming ~800MB of virtual memory, OSX said: (default pager): [KERNEL]: no space in available paging segments Some posts on the web explained what was happening. To summarize: * virtual memory is created by the dynamic_pager in /private/var/vm/swapfile* * disk I/O goes to the roof when the OS needs more swap * if the box cannot keep up the I/O and thus cannot satisfy the pager, it assumes -ENOMEM and will print the message above IOW: get more RAM (or faster disks) :) We could also play around with the pager: sudo dynamic_pager -H 40000000 -L 576870920 -S 536870912 -F /private/var/vm/swapfile