OS/2, eCS & ArcaOS - Technical > Applications
AOS RAM Disk
Andy Willis:
--- Quote from: Dave Yeo on September 26, 2018, 02:35:23 am ---You can put the swap file there too and in theory run a bunch of processes that use lots of memory and it would swap. In practice, IBM seems to have used 32 bit variables in too many places for this to work.
--- End quote ---
I put my swapper.dat on the RAM disk just so that it wasn't writing to the SSD drive every boot but given we can't use over 4G I don't see how the swapper could ever be used.
Dave Yeo:
What happens if you start up 5 processes that each use a GB of memory?
In theory you should just get some swapping but as I mentioned, OS/2 seems to use 32 bit variables that limit the size of virtual memory. The swap file itself is limited by using signed 32 bit based on what happens if you grow it more then 2GB (same thing as if you run out of disk space) based on experience. It makes sense as all file systems had a 2GB file limit before JFS.
The i386 is quite capable of handling 16 TB of virtual memory IIRC, but only 4 GB of address space
Valery Sedletski:
--- Quote from: André Heldoorn on September 25, 2018, 09:14:45 pm ---
--- Quote from: Valery Sedletski on September 25, 2018, 08:00:31 pm ---I always thought, it is a 4 GB, not 4 MB limit. Am I not right?
--- End quote ---
You may not be right indeed: https://en.wikipedia.org/wiki/Gibibyte... :P
--- End quote ---
I don't use term "GibiByte". It is not "real" term. I use only real term "GigaByte". 1000 MB is not a gigabyte. Gigabyte was always 1024 Megabytes.
Doug Clark:
Is the AOS RAM disk bound by the same limitations as file systems on "normal" disks,
or is there some magic going on in this app?
Without thinking I set my machine up some months ago with an 8GB HPFS RAM disk and have
been operating that way for months - although I don't think I have ever copied more that
2 GB to the RAM disk.
But what would happen if I did?
If I remove the line
IFS=C:\OS2\HPFS.IFS /CACHE:2048 /CRECL:4 /AUTOCHECK:*
from CONFIG.SYS I get the error
The specified disk or diskette cannot be accessed
C:\MPTN\BIN\VDOSCTL.EXE
The help for RAM disk says, in part
"The AOS loader can format the drive(s) it creates using FAT, FAT32, or HPFS; it can also leave them unformatted. Both drives will be formatted the same way. Note that if you choose FAT, any drive over 2gb will be left unformatted."
but it doesn't say anything about other file system types.
I tried using FAT32 but that makes the RAM drive VERY SLOW when copying files to and from the disk.
Finally - I tried setting the "Format partitions using" to none and using the WPS disk object
to format the RAM disk as JFS, and the application I was running (VLC) that was reading files
from the RAM disk started behaving badly.
And the final question: If I don't have any other partitions, other than the RAM disk,
formatted as HPFS, do I really need the /CACHE:2048 clause the IFS statement in CONFIG.SYS?
Doesn't seem to make sense to cache a RAM disk in RAM.
Dave Yeo:
I think you could remove the cache statement, or at worst shrink it to 64 if removing it seems to screw things up.
Personally, I reformat as JFS, see my other reply.
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