root@cca.ucsf.edu (Systems Staff) (07/03/90)
In article <2389@nisca.ircc.ohio-state.edu>, karl-d@nisca.ircc.ohio-state.edu (Doug Karl) writes: > This is a summary of the responses I received from an earlier posting. > With a plea for help in adding an allocate function to future > releases of Unix. > > REVIEWING EARLIER POSTING: > > I am in desperate need to allocate a Unix (BSD 4.3, SUN/OS, System V, > and NeXT/Mach) file prior to using it. By "allocate" I mean that all of > the blocks in the file (10's of megabytes long) should be reserved to that > file instantly). ... > - Some suggested I record to a raw partition and then copy to a Unix partition. > --> This would take 32 minutes to copy after the 2 minutes of recording <-- A raw partition is a Unix partition; perhaps you meant copy to a Unix "ordinary file"? Why would you want to copy it? Just read the disk partition as a file. That's why they're called "special files" and they're straightforward to use. Also you have you choice whether you want to read it as raw or buffered. All you need is the appropriate permissions on it. Actually, I suppose you may want to have more than one "pseudo file" in a partition but since you can seek on the partition you could subdivide it as you like. > - One person commented that holey files have been a thorn in the side of Unix > for years and that is just the way it is! (maybe he ment holy files). Maybe he meant "holey files" as he said. See e.g. Webster's Collegiate Dictionary holey: having holes And "holey files" with their ability to accommodate sparse data files economically have been a great feature of Unix. There is, however, a genuine problem with Unix type systems for problems like yours that should be easier to deal with in Mach based systems. Standard Unix disk I/O is always "blocking" (i.e. the request must complete before the process continues) so you need to juggle multiple processes to stream the data. For an example of a program which attempts this see the program "ddd" in volume 15 of the comp.sources.unix archive. Thos Sumner Internet: thos@cca.ucsf.edu (The I.G.) UUCP: ...ucbvax!ucsfcgl!cca.ucsf!thos BITNET: thos@ucsfcca U.S. Mail: Thos Sumner, Computer Center, Rm U-76, UCSF San Francisco, CA 94143-0704 USA I hear nothing in life is certain but death and taxes -- and they're working on death. #include <disclaimer.std>