[comp.sys.apple] GS RAM disk

da1n+@andrew.cmu.edu (Daniel K. Appelquist) (11/29/88)

Why does the Ram disk always who bad blocks when you set the maximum and minumum
values differently?  The only way my ramdisk is usuable is if the max and min
are set exactly the same. Any other configuration leads to "bad blocks."  Any
theories or suggestions?

   Dan

shawn@pnet51.cts.com (Shawn Stanley) (11/30/88)

da1n+@andrew.cmu.edu (Daniel K. Appelquist) writes:
>Why does the Ram disk always who bad blocks when you set the maximum and minumum
>values differently?  The only way my ramdisk is usuable is if the max and min
>are set exactly the same. Any other configuration leads to "bad blocks."  Any
>theories or suggestions?

What program(s) give you the bad block errors?

UUCP: {rosevax, crash}!orbit!pnet51!shawn
INET: shawn@pnet51.cts.com

apoy@caen.engin.umich.edu (Alfred Lim Poy) (12/02/88)

From article <0XYS30y00V45NO5Vc-@andrew.cmu.edu>, by da1n+@andrew.cmu.edu (Daniel K. Appelquist):
> Why does the Ram disk always who bad blocks when you set the maximum and minumum
> values differently?  The only way my ramdisk is usuable is if the max and min
> are set exactly the same. Any other configuration leads to "bad blocks."  Any
> theories or suggestions?
> 

I've run into the same problem.  When I select a group of files to be 
copied into the ram disk,  the first 100K or so will copy ok but then
the finder comes back with a bad block or system error.  I usually
have the min at 0 and the max at 256 (but it happens with the max
higher also).  This happened with both System 3.1 and 4.0 so I don't
think the problem is GS/OS.  I just tried setting both min and max
at 256 and tried to copy 7 files of 150K total into ram5 ( done by
selecting all 7 at the same time).  Guess what: It worked fine !!!!!
Confused? Me too.

                                 Al Poy

mattr@pro-beagle.cts.com (Matt Reimer) (12/03/88)

When the Control Panel settings are not the same, memory for the RAM disk is
allocated on an as-needed basis.  If the RAM disk needs to expand but there's
not enough memory, it returns a bad block error.

What happens when you're trying to copy a bunch of files with the Finder is
that the Finder reads a many of the files as it can into memory, and then
writes them to disk.  Now when it tries to write them to the RAM disk, there
may not be enough memory to enlarge the RAM disk, so a bad block error is
returned.

This problem won't show up if you have lots of RAM or you copy a smaller
amount of data at one time.  Also, once the RAM disk allocates memory it is
not released, so once the RAM disk reaches its maximum size this problem won't
show up.

Matt Reimer
mattr (pro-beagle)