tkav@allgfx.agi.oz (Tony Kavadias) (04/12/91)
I have explored with System 7.0's virtual memory feature and have found that System 7.0 doesn't require contiguous hard disk space to implement virtual memory! I tried loading my 40MB hard disk to the brim, then trashing some stuff to purposely make fragments in my hard disk space. I also checked this using Norton Disk Utilities and SUM II (just to make sure). I had, according to the Finder, 8 MB of hard disk space available, so I turned on virtual memory with as much space as I could assign (which was indeed 8 MB), and restarted my Mac. WOW! No more fragmentation worries! There it was, an 8 MB Mac (I had 5MB of real memory). I didn't believe it for a moment - I ran Norton again to check, and yes, I could see the virtual memory file, split up into little pieces. You don't need to run Norton to defragment your hard disk every time you turn virtual memory on, like previous virtual memory software for System 6.0.x. I guess not many people would like this, thinking "isn't that going to slow down the machine?" I don't know, and I can't make a comparison (System 7.0 seems to be more disk intensive than System 6.0.x ever was). But I wouldn't think the Mac's performance would suffer so much as to be noticed (would anyone like to volunteer to check this for me?). But, well, that's news for you. (I haven't seen anyone address this topic about virtual memory and System 7.0, so I thought I'd bring it out for those who might be interested...) Tony Kavadias, | I don't think I'll bother about putting All Graphic | quotes at the end of my email; I just like Melbourne, Australia. | reading what others write... tkav@allgfx.agi.oz.au
thomas@duteca (Thomas Okken) (04/24/91)
From article <1991Apr12.103710.3900@allgfx.agi.oz>, by tkav@allgfx.agi.oz (Tony Kavadias): > WOW! No more fragmentation worries! There it was, an 8 MB Mac (I had 5MB of > real memory). I didn't believe it for a moment - I ran Norton again to check, > and yes, I could see the virtual memory file, split up into little pieces. > You don't need to run Norton to defragment your hard disk every time you turn > virtual memory on, like previous virtual memory software for System 6.0.x. Actually, this isn't quite true: I'm using Virtual 2.0.4 on a Mac II, and it will automagically move data around on the hard disk to create enough contiguous free space. Which is what you want anyway: a fragmented swap file can only slow things down, now matter how little, and any unnecessary slowdown is too much, IMHO. - Thomas (thomas@duteca.et.tudelft.nl)