Path: utzoo!attcan!uunet!overload!dillon From: dillon@overload.Berkeley.CA.US (Matthew Dillon) Newsgroups: comp.sys.amiga.tech Subject: Re: Virtual Disk (Was Re: Files larger than available memory.) Message-ID: Date: 11 Oct 90 17:34:16 GMT References: <1088@ucsvc.ucs.unimelb.edu.au> <409@tlvx.UUCP> <1124@ucsvc.ucs.unimelb.edu.au> <32892@nigel.ee.udel.edu> <42.2712f4e3@vger.nsu.edu> Lines: 47 >In article <42.2712f4e3@vger.nsu.edu> manes@vger.nsu.edu writes: > >One thing has occurred to me about virtual memory for the amiga. > >Considering the fact that the Amiga operating system does not handle >file corruption very well, what would happen if during a swap a power >fail occurred? Or the machine was turned off? > >It appears to me that the swap device MUST use RAM, and if RAM is used >would the requirement to have RAM to do Virtual Memory be a bit self >defeating? > >I guess what I am asking is -- By using a swap device to a hard disk, >wont we aggrevate the the problems with corrupted files? > >Doesn't this also bring up the question about a 'shutdown' command >again? > >-mark= >manes@vger.nsu.edu It is relatively easy to use a PARTITION on your hard drive for your SWAP space. This is how UNIX does it. You format it yourself and clear the 'swap' space on boot. No files to get corrupted, and since the partition information is never modified the partition itself will never be corrupted, only data inside it which isn't a problem because the data gets cleared when you start up the VM system. In anycase, this is one of the arguments against using a FILE to hold your VM space. Using a partition is less likely to cause problems if you reboot unexpectedly. I've discovered with FMS: (my floppy disk simulator that uses a hard disk file to 'hold' the floppy) that even with a large number of buffers the amiga FFS is not as efficient as one would like Seek()ing in a 1MB file, which leads me to believe that seeking in a 20MB file would be even less efficient. -Matt -- Matthew Dillon dillon@Overload.Berkeley.CA.US 891 Regal Rd. uunet.uu.net!overload!dillon Berkeley, Ca. 94708 USA