(Excerpts from a message dated 10-24-99, Andy Roberts to Murray Lesser)

Hi Andy--

AR>According to the online information "OS/2 Warp Command Reference",
  >"File Allocation Table (FAT): aging gracefully":
  >--- Excerpt ---
 > For small volumes (under 80MB), FAT might actually be faster than HPFS.
  >--- End Quote ---

AR>I think that also implies the inverse that for volumes larger than
  >80MB, FAT might actually be slower than HPFS.

    The following is from the Warp 3 IBM white paper, "Performance
Tuning OS/2 Warp (DevCon disc M1, Release 2 Vol 3, file
\WARPPERF\WARPPERF.ASC):

"FAT is best suited for disk partitions that are 80 MB or less in size
 or that have a limited number of files installed. Usually, 256 files is
 a good target, with up to 500 acceptable...

"HPFS does away with some of the concerns that are prevalent with FAT.
 Files are allocated based on a 512 byte granularity instead of a
 cluster size, therefore fragmentation is greatly reduced. Also HPFS is
 especially efficient when handling large partition sizes, > 100 MB, and
 large numbers of files, > 500.  One thing you should look out for is to
 not allocate more than 5000 files in a sub-directory or directory. When
 you exceed 5000 files, you will start to degrade performance."

     You will note that there is lots of wiggle room here :-).

 ML> but [FAT] has more capacity.

AR>I assume you are talking about added overhead for HPFS that is not
  >necessary for FAT on very small partitions, otherwise:

    Yes, I am talking about the "raw" capacity that is lost in an HPSF
formatted partition and contains no useful (to you) information.  As I
stated, if you format a "100MB" Iomega Zip diskette both ways, you will
find that CHKDSK reports about 3 MB more for the FAT version than for
the HPFS version.  Also, the FAT version "file-space overhead" includes
the space for the first sector of root directory; the HPFS version does
not.

AR>Humm.. I keep thinking about subscribing to DevCon, but I'm stingy.


    AFAIK, all DevCon-distributed documentation is available for free
(Guest) download.  Most certainly, WARPPERF.ASC is marked as available
to Guests in the most recent "Content List" I have.  You can register
for "guest membership" at www.developer.ibm.com/devcon.

AR>Removable media falls into a different class.  1.44MB floppies for
  >example are still limited to FAT, which never ceases to confound me. 

   Too much filespace overhead would be lost out of the 1.44 MB
available if formatted HPFS; there wouldn't be anything left for data
:-(.  Besides, 1.44 MB floppies are about the only medium that offers
"sneaker net" communication between almost all OS/2 and DOS systems.

    Regards,

        --Murray

___
 * MR/2 2.25 #120 * There is no such thing as a free lunch

--- Maximus/2 2.02