[thomas]

As always: "it depends".

For drives up to 8.45 GB (1 GB = 10 to the power of 9 bytes) or 7.87 GiB (1 GiB = 2 to the power of 30 bytes) it is sufficient (and most efficient) to install a file system which supports HD_SCSICMD. You don't need any further patch and can create partitions anywhere and as big as you like. Such file systems are SFS 1.84, FFSTD64 or PFS2/3ds. (Links see in Bloodwych's first post).

For bigger drives you also need a patch for scsi.device. Please note that each patch needs some memory as well as the buffers for partitions need memory. The more partitions you make and the bigger the partitions are, the more buffers you need. For a 40 GB HDD with let's say 10 partitions (historically grown) with buffers for decent performance you might loose 1 or 2 MB of memory. For an A600 this is clearly too much. So for computers with few RAM I would stick with small hard drives.

Nevertheless, you can put scsi.device (any version, preferably 43.45 or 44.2) into the Devs directory and add a line like

loadmodule devs:scsi.device

to the top of your startup-sequence and there you go with big harddrives up to 2 TiB / 2.2 TB. (You see, the difference between binary and decimal measurement units grows significantly in these dimensions. The difference between 2 TB and 2 TiB is 200 GB).

With big harddrives also the limits of the file systems become relevant. With PFS3 you can use partitions up to 107 GB, with SFS up to 128 GB. I don't know the limit of FFS and how it calculates but I am sure that with a block size of 1024 bytes you can safely create partitions of 20 or 40 GB. With SFS2 there is no limit AFAIK (SFS2 = SFS with an identifier of 0x53465302).

For the decision which file system to use you should look into the two tables I mentioned above. Take the version of scsi.device you've got, look up which command sets it supports and choose a file system which also supports at least one of these command sets.

Whether you go the SFS, the PFS or the FFS route is up to your personal taste. SFS and PFS both are much faster than FFS but less redundant and therefore more difficult to recover in case of an error.

Edit: SFS needs a 68020 and PFS maybe too (I am not sure atm). So they are not usable on a plain A600.

(ie. sees standard FFS partition and WinUAE "harddisk folders" for when I backup stuff),

Standard FFS partitions are always seen, because FFS is built into the Kickstart ROM (at least in 2.0 and above).

Harddisk folders are completely independant from all of the above because they are completely handled by WinUAE internally.

And of course you can use as many file systems as fit into your RAM. Each partition can have a different file system. So which file system you use for one HDD is completely unrelated to other HDDs. Only if you try to run all this with a very small amount of RAM, you'll run into troubles.