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Old 22 September 2007, 13:56   #2

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Korodny provides the following advice:

There are a few facts you should consider:

AmigaOS 3.0/3.1 has a 4GB limit. Several parts of the OS have that limitation, it's not just the filesystem:

1. HDToolbox
2. Filesystem
3. scsi.device

HDToolbox will work with bigger drives (if you upated/patched the rest of the components, see below), but it will always give you completely wrong size informations. You may use 3rd party tools like Phase5's SCSIconfig, but always use the same tool - do not mix them!

Using a third party filesystem (PFS, SFS or the new FFS that's included with NSDPatch from Aminet, see below), you avoid problem [2]. These filesystems (at least PFS and SFS also have a "Direct SCSI" mode, which is a workaround for problem [3] (Make sure that you enable this function!!). However, all internal HD connectors of all Amiga models (both SCSI and IDE) have an additional 8GB limit (yeah, that's right, eight GB).

To avoid this 8 GB barrier, you have to replace the scsi.device with a completely new, 64-bit compliant alternative. There are four choices:

1. OS 3.5 / 3.9
2. NSDPatch (should still be available on Aminet)
3. TD64 (written by Ralph Schmidt, available on Aminet)
4. IDEFix (commercial)

TD64 is not compatible with OS 3.5+, so your options are limited to NSDPatch and IDEFix. If you want to go this route, tell me which is your favourite choice, I'll give some further hints then.


Once the filesystem and the scsi.device are able to handle bigger drives, you run into the next set of problems: Never ever format a drive without the QUICK option. The format command still has a 4GB limit (an update is available on Aminet, IIRC). The Info command will display completely wrong size information. Your boot partition must be below the 4GB barrier - as the scsi.device is not patched after a cold boot. The memory needed for a validation process (if one of your partitions gets invalidated) is increasing when the partition size is increasing. Unless you have a lot of memory, you may end up with an endless loop (as the validation process crashes because it runs out of memory - the machine resets - the validation process crashes again). Some OS3.5 betatesters reported that an A3000 with 18MB of memory was not able to validate a 4GB partition. (Note that all these problems have been fixed under OS 3.9).

I would say it's not worth the hassle. Here's my recommendation:

Forget about using everything beyond the 4GB barrier with OS 3.1. Partition the drive with OS 3.9, make one or two partitions (that should be accessible from OS 3.1). Both of these partitions must be below the 4GB barrier (to be on the safe side, stay below 3900 MB).

Alternatively, forget about using OS 3.1 and use 3.9.

Last edited by Bloodwych; 30 September 2008 at 17:07.
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