[Info-vax] Anyone interested in another public access system

[glen herrmannsfeldt]

Bill Gunshannon <billg999 at cs.uofs.edu> wrote:
 
> Yeah, and I remember doing SQUEEZE on my DEC disks.  
> Do we still have to do that on VMS, I wonder?

I remember writing and reading RT-11 floppies on a VAX.
The RT-11 file system stores all files in contiguous blocks,
requiring SQUEEZE to write large files after deleting many small
ones.
 
> 1746 files, 44420 used, 10109779 free (2635 frags, 1263393 blocks, 
> 0.0% fragmentation)
> 19 files, 25064 used, 20286338 free (26 frags, 2535789 blocks, 
> 0.0% fragmentation)
> 6878 files, 289010 used, 25099511 free (5143 frags, 3136796 blocks, 
> 0.0% fragmentation)
> 789103 files, 79801403 used, 156703416 free (197312 frags, 
> 19563263 blocks, 0.1% fragmentation)
 
> User fileserver.  Last one is the users directory.  1400 users filesystem
> shared thru NFS on Unix systems and Samba on Windows system.  All faculty
> and student files are here.

I haven't thought of the details of the unix file system for
a while, but if I remember this one right, it isn't quite
the same.

For systems like DOS/Windows, especially for FAT file system,
one wants files as contiguous blocks.

The unix file systems I remember allocate in larger blocks,
such as 4K or 8K bytes.  (Likely made up of 512 byte disk blocks.)
Large files should be contiguous 4K or 8K blocks, but that is
inefficient for small files or the last blocks of larger files.
To handle small files, the 8K blocks are fragmented and kept
track of separately.  The number you see as frags is really
the number of small files stored in fragmented blocks.

-- glen