My understanding is that aMule can run with "min disk space" space of a bit less than 10 MB. It seems that in a non sparse environment, active downloads have space to complete and aMule presumably will not start a paused file if it is unable to allocate the requisite space to complete?
That's not true.
First of all, in a non-sparse environment the allocated file size is always equal to to the address of the last written byte. That is, if you download a 2.0 GB file, and aMule writes data at 1.5 GB, the system will first allocate the (not yet used) first 1.5 GB, then write the actual data at 1.5 GB. If you write a single byte at the end of the file, the whole file will be allocated, regardless of the size and the amount of space it needs (unless the disk gets full meanwhile).
Since aMule cannot predict when and what will happen on a write, it will happily start downloading a 2.0 GB file even if only 1.0 GB disk space is free.
Considering the above, your choices are:
1) Use a sparse file system. Then aMule will always stop when the free disk space drops under the preset minimum, and will never use up all space on the drive.
2) Preallocate space for new downloads. This ensures that no more disk space will be used while downloading and started downloads can finish. The drawback is, that you must manually ensure that there's enough space on the drive before you select a new file to download.
3) With your settings, you have two choices:
(a) Set min disk space to a low value. That means, aMule will sooner or later fill the whole drive, and you'll get "No space left on device" errors.
(b) Set min disk space to a high value (bigger than your biggest file you want to download). In this case, aMule can't fill the disk, but will leave a lot of space unused.
(c) If you want to make sure aMule can work unattended, you should set min disk space to a low value (so then almost all of the disk space can be used for downloading), and, if you download
n files at once, ensure that there's enough space on the drive for the
n biggest files to complete at once, in addition to the min disk space.
Let's see an example: say, I use a 4.0 GB SSD for downloading, then I move completed files to another HDD. I download CD images approximately 700 MB each. Then I'd set min disk space to the lowest, and not let more than 5 downloads to run at any time, because that will use at most ~3.5 GB, not filling the disk. If I'd let a 6th download start, it might (but not necessarily will) cause a disk full error.
What is the benefit of setting a "min disk space" parameter greater than 10 MB? It sounds like aMule will keep me safe with a 10 MB "min disk space".
If you run aMule on a system where the temporary directory is on the root device, or on the device containing /home in a multi-user environment, it is highly advisable that you don't eat up all disk space from the system (or from other users). System administrators can get angry...
