||Beyond the Four Gigabyte Barrier|
UPDATED: December 19, 1999.
About OS 3.5
It is important to realize that the added NSD support does NOT mean that software that uses a custom file system, such as Movie Shop, will now work with larger hard-drives. If this software didn't work without NSD, it still won't work with it.
Also, hard drive applications such as DiskSalv, Ami-Back Tools, etc. will still not work properly, unless they are updated to support NSD.
OS 3.5 includes updated versions of Info, Format, Diskcopy, FastFileSystem and HDToolBox.
Greater Than 4 Gigabyte For FREE
If you find the alert to be too annoying, there is a patch available on Aminet, disk/misc/FFS43.19_patch.lha, that will disable the warning in the 43.19 FastFileSystem. It should ONLY be used with the 43.19 version though.
Alternatively, if you own OS3.5 but just want to update the hard drive support, you can use the 45.1 version from OS 3.5 with OS 3.1, without any problems.
Versions of Info and Format, that support greater than 4 Gigabyte drives, are available on Aminet for FREE - and it is still safe to use the older HDToolBox (see below).
Some time ago, I purchased two Quantum Fireball 4.3 Gigabyte (GB) hard disk drives. One was intended for AmigaDOS storage and the other for use with MovieShop and the V-Lab Motion video card. What I thought would be a simple and somewhat ordinary task of setting up a couple hard disks, turned out to be a great nightmare of confusion and misinformation.
There has been a great deal of discussion about this topic in newsgroups and emailing lists lately. Unfortunately, there is also a huge amount of misinformation floating around - which, I suspect, has confused some people.
If you are planning on using a hard disk larger than 4 Gigabytes with the Amiga, whether it be for video purposes or other, there are a few things you need to be aware of. Note that applications that bypass the Amiga's file system may not be affected by this problem.
The First Signs of Trouble
As a computer programmer, I recognized what the error was right away; but, that did not mean that I immediately knew how to solve the problem.
What is Really Going On?
If a program attempts to read or write data to an area of the hard disk above the 4 Gigabyte limitation, the data pointer will 'wrap around' (4,294,967,295 + 1 = 0, + 2 = 1, etc.). If this happens while the computer is writing data, existing information on the lower part of the hard disk will be overwritten (See Figure 1). This means that data will be lost and very possibly the Rigid Disk Block (RDB), which among other things stores the partitioning information for the hard disk, will be corrupted.
It gets a little more confusing when you try to determine exactly where the barrier exists; because a Gigabyte is not always a Gigabyte. Have you ever wondered why, for example, a 730 Meg hard disk, after formatting, has less than 730 Megabytes of storage? This is partly because hard disk manufacturers, when it comes to specifications, speak their own language. They refer to one Megabyte as 1,000,000 bytes, but any computer programmer will tell you that one Megabyte is equal to 1024 Kilobytes or 1,048,576 bytes, which is what the Amiga thinks, too. One can only guess what they might be referring to when they say one GB. Gigabyte envy??
The Easy Answer
It is necessary that you set the lower partition to no bigger than 4095 Meg. To be on the safe side with AmigaDOS, I recommend 3980 Meg (See Figure 2). For a 4.3 Gigabyte drive, that would leave 151 Megabytes for the last partition. Name it DEAD0 or something similarly obvious and never format it. You can further divide the lower partition into several smaller parts if you wish, but make sure to not go above 4095 Meg (or 3980 Meg if you want to be really safe). So that you do not see an icon for DEAD0, make sure that the 'Automount this partition' option is NOT checked for that partition.
Figure 2 - Partition Drive
I am not convinced that there is one do-it-all solution. I am also not yet sure that any of the following options work 100%. However, after talking with others, discussing this with the appropriate programmers, and through much trial and error I have come up with some information that will hopefully help you through this Giga-craziness.
The most important thing, and I can not stress it enough, is that you should backup ALL your hard disks before you start playing around with any of this. Technically, the only drive of concern is the one you attempt to use these patches with. However, as I have learned too many times, when things get really frustrating it is easy to accidently re-format the wrong hard disk. In seconds, it will be too late.
Consult each program's documentation for detailed information on supported controllers, setup and usage.
New Style Device - NSD
There are three parts: an updated FastFileSystem (FFS43_19.lha), a scsi.device patch (SCSI_IDE43_23.lha) and the NSDPatch (http://wuarchive.wustl.edu/pub/aminet/disk/misc/NSDPatch43_20.lha) program which adds support for many third party hard disk controllers.
Currently, NSDPatch includes support for the following controllers and trackdisk devices: Amiga's scsi.device and 2nd.scsi.device; Phase 5's 1230scsi.device, 1260scsi.device, 2060scsi.device and cybscsi.device; Draco's dracoscsi.device; HiSoft's squirrelscsi.device; Oliver Kastl's atapi.device; WarpEngine's warpdrive.device; DataFlyer's ExpSys.device; Hardital Synthesis' syndisk.device; BSC's oktagon.device; Ralph Babel's GuruRom omniscsi.device; Microbotics' HardFrame.device; and the diskspare.device. Other devices may also be configurable.
First, it is necessary to install the new file system using HDToolBox. In the main window, select the appropriate drive and then the 'Partition Drive' gadget to get to the 'Partitioning' section. By check-marking the 'Advanced Options' gadget (See Figure 2), select the 'Add/Update...' gadget to get to the 'File System Maintenance' window (See Figure 3). If another file system is already listed you should delete it first using 'Delete File System'. Select the 'Add New File System...' gadget to install the new file system.
Figure 3 - Add/Update File System (NSD)
I have been using this file system via the NSDPatch with Phase 5's CyberSCSI-II module for over a year now, without any problems.
You can get this free software from the Amiga International files area: ????. At this stage, the software is still beta; but, it is very stable. These files are updated occasionally, so keep checking back for newer versions. These programs require OS 3.1.
Track Disk 64 - TD64
Currently, support is included for: Phase 5's 1230scsi.device, 1260scsi.device, 2060scsi.device, Fastlane z3scsi.device and cybscsi.device; BSC's ALF.device and oktagon.device; Draco's dracoscsi.device; Ralph Babel's GuruRom omniscsi.device; trackdisk.device and the carddisk.device. The following devices are not compatible: All Amiga SCSI devices (including scsi.device, 2nd.scsi.device; and hddisk.device); GVP's scsidev.device; and Microbotics' HardFrame.device.
This file system is installed using HDToolBox, in the same way as described above for the NSD file system.
You can get this free software from Aminet: disk/misc/ffstd64.lha
Figure 4 - Add/Update File System (TD64)
Bigdisk is a commercial program written by Janos Farkas. It was designed for use with MovieShop (V-Lab Motion) and is currently the only known solution to work with it. However, it can also be used with the Draco and AmigaDOS 2.0 or greater. It has not been tested, but it may even work with earlier versions of AmigaDOS.
Bigdisk approaches the 4 Gigabyte barrier in a different way, taking advantage of the SCSI command set to access the full capacity of a hard disk. When you start the Bigdisk initializer (Biginit), it overlays a new bigdisk.device over the existing device (scsi.device or other) and divides the destined hard disk into 4 Gigabyte sections, creating several virtual drives. Bigdisk 'Unit 0' refers to the first 4 Gigabytes of the original device, 'Unit 1' to the second 4 GB, and so on. Requests sent through Bigdisk are redirected and passed on to the underlying device which can then handle them properly (See Figure 5).
Figure 5 - Bigdisk Virtual Devices
The program has been tested and is known to work with the Amiga's scsi.device and z3scsi.device; and the Draco's dracoscsi.device. At the time of writing, it did not work with Phase 5's cybscsi.device. Other devices may or may not work. Fortunately, a free demo is available which allows you to test the program with your system.
To get the demo, ordering information or other details, visit the Arthur Wilkins Software website at: www.acomp.hu/awsw/bigdisk.html
When it comes to using hard-drives larger than 4 Gigabyte, the Amiga does have some problems. But the solutions described here, in particular NSD, are safe and very reliable.