page@swan.ulowell.edu (Bob Page) (08/01/88)
anthes@geocub.UUCP (Franklin Anthes) wrote: > - is FFS a totally new FS, or just changes made to the old FS? Changes made to the old FS. But it's totally new (written from scratch, in assembler, and not in ROM). > - What changes have been made? It no longer stores the 24-bytes of 'header' information in data blocks, so can now do multi-block DMA transfers to the user's buffer (if the controller and application support it) since it's just 512 bytes of real data per block. It also hashes the files differently for much faster directory searching. It supports a LOCK/UNLOCK dos packet to write (and read?) lock your disk. It does some other things differently (like pre-allocating bitmap blocks) but I don't think you want that kind of detail. > - Why does FFS for diskettes have to wait until 1.4? Because trackdisk.device is in ROM, and it calls the filesystem in ROM when you first boot the Amiga. So there are already filesystem handlers (the old ones) controlling the drives. It is possible to wrestle control away and make FFS run on floppies, but it's not supported and also dangerous because FFS can't yet tell when you change floppies, so its caching (for example) is incorrect. People who do this, no matter how careful they are, will eventually trash one of their floppies. > - Has something been done to make directory access faster, or will the > the speedup in this area just be proportional to the speedup for > FFS? The directory access is much faster. > Frank Anthes-Harper Keep in mind I'm only repeating what I read in magazines and in electronic forums; everything I mentioned was based on a product that doesn't not exist and may change a hundred times if/before it comes out. Don't go building products with this information. ;-) ..Bob -- Bob Page, U of Lowell CS Dept. page@swan.ulowell.edu ulowell!page "What a wonder is USENET; such wholesale production of conjecture from such a trifling investment in fact." -- Carl S. Gutekunst
cmcmanis%pepper@Sun.COM (Chuck McManis) (08/02/88)
These questions get asked a lot but they are fairly topical, if someone has the time to create the "intro" message these should be included for now, then their 1.4 equivalents should be substituted next year... In article <260@geocub.UUCP> anthes@geocub.UUCP (Franklin Anthes) writes: > - is FFS a totally new FS, or just changes made to the old FS? Yes and no. Yes it is a totally new file system handler, however the way the data is stored on the disk is not changed in a really remarkable way. The only real difference is that datablocks now have 512 bytes of data rather than 488. [Yes, that's a "free" 5% increase in space] > - What changes have been made? Biggest wins come from sequentially ordered hash chains and full data blocks. It makes long reads much more appealing (and DMA much more efficient). > - Why does FFS for diskettes have to wait until 1.4? Because it won't be in ROM for 1.3, so there is this chicken and egg problem where you have a disk and no filesystem in memory yet that can read it, because the filesystem is on the disk you are trying to read. See the problem ? Further, some of the stuff that diskettes rely on (like the ability to deal with being swapped out) is not part of FFS yet. > - Has something been done to make directory access faster, or will the > the speedup in this area just be proportional to the speedup for > FFS? Yes, all aspects of disk activity are faster. My wife (who uses a PC-AT at work) commented the other day at how fast the directory popped up on the screen. Such are the improvements. Anyway, with FFS all hard disk activity on the Amiga are faster than equivalent activity on the Mac, PC, or Atari. No I don't know when it will be available. Sorry. --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you.
jdow@gryphon.CTS.COM (J. Dow) (08/02/88)
In article <260@geocub.UUCP> anthes@geocub.UUCP (Franklin Anthes) writes: > > I've heard about the new FFS which will be available with 1.3. > > I've been wondering about a couple of things: > > - is FFS a totally new FS, or just changes made to the old FS? Yes - it is an entirely new file system built to be compatible with the old at the software interface level. The disk format is quite different although there is still only one directory entry per block. The speed up is in file transfers and more intelligent use of buffers and in more intelligent use of disk space (clusters directory entries and searches 'em more intelligently. > > - What changes have been made? See above. Much faster... > > - Why does FFS for diskettes have to wait until 1.4? It can now be used on floppies - doing so is cumbersome and not all that productive. Until it is loaded into the machine, though, nothing can use it. So the boot disk must either be 1.3 automount/autoboot and load ffs from its own image stored on a boot track or from a file on an old-fs df0:. > > - Has something been done to make directory access faster, or will the > the speedup in this area just be proportional to the speedup for > FFS? Again see first answer. Directory searches are significantly faster. >-- > > Frank Anthes-Harper >Usenet: ....!ucbvax!decvax!uunet!mcvax!inria!geocub!anthes {@_@} -- Sometimes a bird in the hand leaves a sticky deposit. Perhaps it were best it remain there in the bush with the other one. {@_@} jdow@bix (where else?) Sometimes the dragon wins. Sometimes jdow@gryphon.CTS.COM the knight. Does the fair maiden ever {backbone}!gryphon!jdow win? Surely both the knight and dragon stink both stink to high heaven.