logo.gif (6996 bytes)
Drives larger than 4 GB

Drives larger than 4 GB
SCSI direct

To use a drive which is larger than 4 GB (4096 MB) you'll need to have a filesystem which supports such drives and you'll need a device which can handle these drives.

Getting a filesystem which supports drives larger than 4 GB is easy. Smart Filesystem can handle such drives correctly. There is also a patch or upgrade freely available for FastFilesystem. This will upgrade your version to V43 or V44.

Now you need to make sure if your device also supports drives larger than 4 GB. If your device supports any of the following, then it should be able to handle such drives:

  • Your device is a New Style Device (NSD) which supports 64-bit addressing.
  • Your device is TD64 compatible.
  • Your device supports SCSI direct access. Even devices for IDE harddisks can support this.

Of course you'll need to make sure that your device and the filesystem your using speak the same language. If you've got a device which supports SCSI direct, but doesn't support NSD or TD64 then you won't be able to use this device for drives larger than 4 GB with a filesystem which doesn't support SCSI direct but only supports NSD or TD64.

Therefore I've included two lists so you can see which protocols some Devices and Filesystems support. The list aren't complete. I'll need your help to extend the lists, so if you have got more information send me an e-mail.

DEVICES Version NSD(64) TD64 SCSIdirect
scsi.device (A1200/A4000) 43.21 yes no yes
cybscsi.device (Cyberstorm) 8.1 no yes yes
HardFrame.device (Microbotics) ? ? no ?
statram.device (Ram Disk) ? ? no no
ramdrive.device (Ram Disk) ? ? no no
scsidev.device (GVP Series I) ? ? ? no
hddisk.device (CBM A2090) ? ? ? no


FILESYSTEMS Version NSD(64) TD64 SCSIdirect
FastFilesystem 43.18 yes no ?
FastFilesystem 44.5 no yes no
SmartFilesystem 0.71 yes yes yes (*)

(*) Use the SCSI direct version.

It's a very good idea to add some checks to your startup-sequence to see if your using the correct version of your device and filesystem. If for any reason you're using the wrong versions then you could easily end up destroying your data. That's why I have added these lines to my User-startup:

 Version DH1: VERSION=44 >NIL:
   ECHO "Warning!  V44 FastFilesystem is not loaded!"
   Version DH1:
 Version scsi.device VERSION=43 >NIL:
   ECHO "Warning!  V43 scsi.device is not loaded!"
   Version scsi.device

You'll probably need to modify these checks a bit for your own setup.

Finally, don't use tools like ReOrg, DiskSalv, DynamiCache, PowerCache, AmiBackTools, QuarterbackTools and similair tools on partitions which are located after the 4 GB border. They don't support drives larger than 4 GB and will destroy data on other partitions if you use them!

Always be absolutely sure your tool supports drives larger than 4 GB before using them! If you've got a tool and it reports errors or acts strangely when working with one of your partitions after the 4 GB border (for example, DiskSalv doesn't recognize that a disk after the 4 GB border is FFS) then that tool probably doesn't support drives larger than 4 GB.

Also be careful with the standard Format command! Always use the QUICK option for drives larger than 4 GB, otherwise format may format information in the wrong area of your disk!

See the SCSI direct page to learn about SCSI direct and how it could be useful for drives larger than 4 GB.

All rights reserved.
For comments, problems or questions regarding this page contact John Hendrikx.
Last updated: 04 augustus 1998.