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Text File | 2022-11-05 | 15KB | 321 lines

$7ff|1- WARNING TO ALL HARD DISK USERS! $fff Amida/Crn $fffThis textfile mainly concerns those who are considering upgrading to a larger hard drive for their Amiga. It also addresses issues to those particularly with large HDs (4.1Gb+). This textfile only covers an abstract (non-technical) level of detail but gives important advice on a subject that cannot be ignored. $fdfLarge harddrives can be incompatible ==================================== $7ffThe most recent an unexpected event has occurred with my HD, and its one of the reasons why I wanted to discuss the potential dangers of owning a large HD. Days after I received my fully working A4000 I began configuring my 4.3G HD. The first event was my WB boot partition had been corrupted, in the second event all my partitions have been lost! Luckily all my files have been recovered and many had been backed up. I wondered why and what caused this problem. The main cause had been in circulation on my current version of AmigaDOS. Yes, that was to say that AmigaDos 3.0 (KS39.106) in early A1200s and A4000s cannot manage hard drives larger than 4.1G. And now I have already conducted tests on how to avoid faults and recover from errors before creating this textfile. $bf0Eyetech's article on HDs ======================== $af0At first I disagreed with Eyetech's AD which they wrote about the limitation of AmigaDOS against 4.1G+ HDs. Its hard to believe - but they were telling the truth. But their lack of elaboration could lead most users into confusion and misunderstanding and I presumed that this limitation only applied to OS versions below 3.0, and you rarely hear that OS3.1 is required over OS3.0 for many hardware/software requirements. There is only one case which I have seen, the use of advanced Zorro III graphics cards, OS3.1 have chunky pixel conversion whereas OS3.0 doesn't (which relies on the gfx card to do the job), only OS3.1 is favoured by Picasso IV to operate and not OS3.0 (for graphical reasons). And also - you would not expect OS3.0 to differ from OS3.1 in anyway especially in the areas of handling filesystems. There may be other possible bugs and limitations of the 3.0 chip which we ought to know but we don't know they exist until something goes wrong. There's insufficient info. out there that leads us to believe that a difference between both OS3.0 and 3.1 do exist. How many people do we know who understands the differences between these two OSs? $ff8Do you want to buy a 4.1G+? =========================== $8ffWell if you decided to purchase a drive whether 4.3G - 6.5G whatever for your OS3.0 Amiga then certain solutions can be considered: 1. Are there patches to overcome limitation? 2 Expansion board on A1200s that support MAPROM enabling a more recent kickstart image to be stored and used. (Blizzard 1230IV are one of many boards). 3. Certain SCSI controllers e.g. A2091 for Amiga A2000 allows MAPROM bahaving the same as the Blizzard. As you can see the problem is mainly associated with the OS. $faaLarge HDs under OS3.0 ===================== $bf0In my tests AmigaDos3.0 (whether you're using A1200 or A4000) can accept any partition size up to 4.1G. On a brand new HD of 4.3G, you can use HDtoolbox from WB to create and position any sized partitions as visible "blocks" (I will refer partitions as blocks in HDtoolbox) anywhere on the window, and as you like. But it is wrong for HDtoolbox to allow for this because in theory you can only create a block no greater than 4.1G (fig. 1.0) or create many blocks which doesn't exceed the 4.1G legal limit (fig. 1.1). +--------------------------------------------------+-----------+ | | | | | | | ONE PARTITION | Unused | | | | | | | +--------------------------------------------------+-----------+ ^ ^ | | 4.1Gb 4.3Gb (boundary limit) fig. 1.0. 1 x partition/block. Partition size = 4.1Gb. Total HD capacity = 4.3Gb. AmigaDos = 3.0 +-----------+--+-+----+----+-------+------+--------+-----------+ | | | | | | | | | | | | | | | | | | | | | 1 |2 |3| 4 | 5 | 6 | 7 | 8 | Unused | | | | | | | | | | | | | | | | | | | | | +-----------+--+-+----+----+-------+------+--------+-----------+ ^ ^ | | 4.1Gb 4.3Gb fig. 1.1. 8 x partitions/blocks. Partition sizes vary but do not exceed 4.1Gb. Total HD capacity = 4.3Gb. AmigaDos = 3.0 The above diagrams are maximum acceptable setups to AmigaDos3.0. Note: As mentioned before HDtoolbox will allow you to create and sized partitions as preferred by the user (fig. 1.2 and 1,3) AND IS NOT ALLOWED IN AMIGADOS3.0. +-----------+--+-+----+----+-------+------+-----------+-------+ | | | | | | | | | | | | | | | | | | | | | 1 |2 |3| 4 | 5 | 6 | 7 | 8 |unused | | | | | | | | | | | | | | | | | | | | | +-----------+--+-+----+----+-------+------+-----------+-------+ ^ ^ | | 4.1Gb 4.3Gb fig. 1.2. 8 x partitions/blocks. Partition sizes vary but no.8 has exceeded the 4.1Gb limit. Total HD capacity = 4.3Gb. AmigaDos = 3.0 +-----------+--+-+----+----+-------+------+----------+-+-------+ | | | | | | | | | | | | | | | | | | | | | | | 1 |2 |3| 4 | 5 | 6 | 7 | unused |8|unused | | | | | | | | | | | | | | | | | | | | | | | +-----------+--+-+----+----+-------+------+----------+-+-------+ ^ ^ | | 4.1Gb 4.3Gb fig. 1.3. 8 x partitions/blocks. Parition no.8 is beyond the 4.1Gb boundary. AmigaDos 3.0 will not be able to handle setups for setups on fig. 1.2 - 1.3. The effects, however, will only take place if you perform full format on partition no.8 (NOT QK FORMAT). The result will cause partition 1 to be completely destroyed, this occurs once after you have rebooted the system. Presuming that partition 1 was the bootable partition, you will notice the error as your system will not boot! All other partitions 2-8 will remain intact. To recover files from screwed up partition 1 is quite possible but will depend on what effect that was done to partition 8 prior to rebooting the system. Its difficult to explain... Due to the smaller size of partition 8 there's a good chance that many files can be recovered from partition 1. The varying sizes and position of the last partition will affect the recovery of files in the first. An easier way to picture this is to imagine a piece of paper of length from the start of block 1 to the 4.1Gb boundary limit (as the AmigaDos limit). If you slowly shift the paper to the right this will cross the boundary limit and therefore no longer support the files of block 1. And the further the paper reaches the far right, the less likely that files can be recovered from block 1. What you can recover is the entire filesystem and directory structure, but many of the files will be truncated and corrupted. So if you performed full format to partition 8 before rebooting the system, this causes this effect of losing partition 1. This problem wasn't quite severe if compared to the next stage. +-----------+--+-+----+----+-------+------+--------------------+ | | | | | | | | | | | | | | | | | | | 1 |2 |3| 4 | 5 | 6 | 7 | 8 | | | | | | | | | | | | | | | | | | | +-----------+--+-+----+----+-------+------+--------------------+ ^ ^ | | 4.1Gb 4.3Gb fig. 1.4. 8 x partitions/blocks. Full hard disk is used. In the diagram above block 8 has been used as a full partition. This is clearly not allowed in AmigaDos3.0. On saying before if you full format on partitions 1 to 7, nothing happens but full formatting partition 8 will cause partition 1 to be destroyed. If you fill your partitions with files (anything) - nothing will occur. NOW IF YOU FILL PARTITION 8 WITH FILES TO FULL OR EXCEED THE 4.1G BOUNDARY AND REBOOT THE SYSTEM YOU HAVE THEN LOST >>>>ALL AND EVERY SINGLE PARTITION ON YOUR HARD DRIVE<<<< What actually has happened: the file system has been resetted to the default setup as like launching HDtoolbox for the first time on a brand new hard drive. The filesystem may be lost but files can be recovered. Methods: Quickest and best method: You can restore all partitions by recreating them according to their original values in size and position (but you must have recorded their values before the error occurred). This will restore everything back to its normal state as if nothing has occurred. For this example you must recreate all partitions according to figure 1.4. Here's a test: 1. Remember all your partitions in terms of sizes, position and name. 2. Delete or rearrange a partition using HDtoolbox 3 Save changes 4. Reboot Partitions gone? You can use HDtoolbox again and rearrange the partitions to their precise and original state as recorded in step 1. All partitions should be visible and has returned to their normal state. 2nd recovery method: The worst method is to recover your files from a corrupted file structure, once they are all recovered - you will need to arrange them into directories. This takes a very long time (especially for 40,000 files). You must use QUICK FORMAT before using any HD recovery tool such as Amiback Tools or Quarterback Tools. To recover a HD from lost partition, you should never use that same HD as the recovery destination. If its all you have then I would use floppies. I used my A600's 1.1G HD daisy chained to the A4000 as the recovery destination and when it became full I used my Tape Drive to backup all files before freeing more space. Data can be recovered even if your HD has been repartitioned. If your hard drive has been wiped completely in just a split second (e.g. whilst running a Scene Demo) then data can still be recovered. This type of method in destroying data could only mean re-partitioning your hard drive and/or destroying your file structure. To wipe data from your drive takes much more than a split second of hard disk activity. It involves full formatting, optimising, wiping unused space and overwriting data or unused space. Don't expect data to be lost if something unexpected has occurred in over a flash. Only if overwriting of a file occurs. The old file can never be recovered because it has been overwritten by the same filename in that directory and (usually) within the same block (in disk terms). $ff7Tips for those who are unsure ============================= $ff9If you happen to buy a large HD, try and test the drive by giving it many partitions various different sizes but bearing in mind the 4.1G figure limit. Save changes (then reboot) and format your partition using FULL FORMAT from WB (NOT QUICK FORMAT). This will prove to be an effective test for errors and faults. Quick format will only create you a new hard disk filesystem that is ready to be used by the Amiga, it does nothing to ensure that you have a fully working hard disk. Even full format may take long depending on CPU and partition size at least it proves very important at this stage of test and its worth the small hassle of waiting. $bffA hard drive timebomb ===================== $fffIn a real world, a hard drive is an item which you value. But the data is even more important. Data can be seen as a collector's item (images/mods/work) which is increased from being empty to full. The data can be a life's worth of collected items. But as the hard drive becomes full, the point at which the OS fails to cope with the amount - all your partitions (and visible data) are gone! A hard drive timebomb. Occurs with HDs larger than 4.1G on AmigaDos3.0. Or a HD waits until it reaches to a certain capacity before dying. $ff6Avoiding the problem ==================== $f9fConsidering the problem in the earliest stages is important as you never know what could happen in future. Make regular data backups. You can create a Database or directory structure can often help as it will give you indications of ways to organise your data into directories from unrecoverable file systems. Amiback tools has this function. Make important notes such as what the actual sizes of your partition(s) before going to corruption. You can always revive your partitions without corrupting any data. Its important to back up data, don't wait until something occurs, sooner you'll regret it. My HD is currently set as in figure 1.1. Just over 200MB (from 4.3G) is unused for obvious reasons. For a 6.5G, you will need to sacrifice 2.4G (a huge waste of space) to work within the OS limit. Until now for a month no problems have occurred. Its "quite" possible to daisy chain large HDs together. I had no problems connecting a 4.3G drive with a 1.1G in my A4000. I wondered if 2 x 4.1G drives are allowed. Well I hope this textfile helped. Just to remember, anything you do will be done at your own risk, I can not be held responsible for any damage or losses of data. $fffAmida. $fffend