Maximum LMFS File Size

[Dodds@YUKON.SCRC.Symbolics.COM (Douglas Dodds)]

    Date: Thu, 18 Apr 1991 10:32 EDT
    From: Steve%BALROG.it.drea.dnd.ca@Warbucks.AI.SRI.COM (Steve Lawrence)

    I need to work with fairly large files ~35 MB and I have been having
    some problems.  Therefore, as a start to tracking down my problems: Is
    there a maximum LMFS file size (ignoring the constraints of disk space
    and partitioning) ?  Does this vary between 3640s and MacIvorys ?

This is a frequently asked question that has somehow escaped
documentation, as far as I can tell.  I'm trying to get that corrected.
Here's the rough story, as I have been able to gather it:

There are actually two limits: one is the limit you hit if you open an
empty file and just keep outputting to it until it runs out.  The other
is much larger, and applies if you allow the filesystem to preallocate,
by opening the file with :ESTIMATED-LENGTH <nbytes> (some kind of
reasonable guess at the eventual size).

The limits are numbers of blocks, and so in bytes they do vary somewhat
with the machine architecture.  Empirically, the first kind of limit is
15.7MB for 36xx servers, and about 19MB for XL servers.

I don't know what the theoretical limit (beyond the actual length
estimate, that is) is, but I'm told it is large enough that you will
always exceed the space available in the partition first.  In the same
empirical test, except using an :ESTIMATED-LENGTH, I wrote 36MB to a
36xx before running out of partition space.

So maybe that technique will enable you to use LMFS for your large
files.