OS/2, eCS & ArcaOS - Technical > Applications

AOS disk size limitation?

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Doug Clark:
Is the AOS RAM disk bound by the same file system limitations as "normal" disks?

Meaning - is an AOS HPFS formatted to HPFS limited to 2GB - as is normal for HPFS?  Or does the RAM do something "special" that allows it to transcend regular file system limitations?

Without thinking about this I set the RAM disk up to use 8gb of high memory format as HPFS and have been booting that way for months.  I don't think I have ever copied more than 2 GBs to the RAM drive - but what would happen if I did?

The help says is "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."

Since JFS is not an option on the RAM disk setup dialog I switched to FAT32 - but that makes the drive VERY SLOW.

I also tried reformatting the drive as JFS using the WPS drive object but the application I was running using files on the RAM disk (VLC) started behaving very strangely.

I seem to remember having to put IFS=HPFS

Dave Yeo:
The limit for OS/2 HPFS is 64GB, in practice somewhat less, perhaps 60GB for stability, so a 8GB ram disk is no problem. The 2GB limit is the file size limitation on HPFS.
If you want JFS, add this to startup.cmd (ram disk is H: here, adjust as needed)

--- Code: ---if exist H:\jfs.part goto next
sleep 1
touch h:\jfs.part

--- End code ---
And create reply_y.txt besides startup.cmd in the root of your boot volume containing Y
This will preserve the JFS volume across reboots if you've set the ram disk to preserve its contents and your hardware allows it.

Doug Clark:
Thanks Dave for the info.

Sorry I posted this twice - I thought the first post had disappeared and so I re-posted.

What drove me to JFS from HPFS was the difference in CHKDSK times.  CHKDSK on HPFS takes forever on large volumes.   Since a RAM disk  gets thrown away on reboot CHKDSK is a non-issue.  And the "thrown away on reboot" is, for me, one of the advantages of a RAM disk.   Fits right in with my lazy, never get around to it,  disk  housekeeping tendencies.

Doug Clark:
Thanks Dave - the format routine is clever.

Dave Yeo:
Doug Bisset came up with the format routine, I expanded it to keep the JFS volume there between warm reboots.
I often use the ramdisk as a scratch work area, so like it to be preserved for a warm reboot, which includes the system dump keys (CTRL-ALT-F10 twice) when the OS locks up, which does mean running chkdsk on the ram disk.
Eventually there's a cold reboot to clean the ram disk and even with only a 4GB ram disk, I haven't had it fill up.


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