Shutdown functionality missing and people seem to like it like that?

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I was on a forum, and a user started a post about software shutdown functionality, and the consensus seemed to be that it’s a “PC” feature that is not needed, you should just shut it down. Do people here agree? Isn’t that a bit short-sighted, since it makes it impossible to do proper filesystem write caching, and thus affects performance? Also, if you’re running a database or other kind of server, it makes it impossible for it to cleanly exit…

  • TenLeftFingers
    I was also interested in this question but never got around to answering. Lets see who can chime in. As far as servers and applications, cleanly shutting down (for example the apache service) takes care of that. But I suspect the hardware cant support it without expandingeither the PSU or adding hardware where the stepping down is done in the machine itself. Because if AmigaOS shuts down while power is supplied, how do you turn it back on. Maybe a suspend mode is possible.
  • Laurent Giroud
    With all due respect this is not a technical question but invites a discussion which frankly would have no end. The question should IMHO be rephrased to be more productive for example: “Why is there no shutdown functionality?” or “How-could a shutdown functionality be implemented?” which are purely technical and hence would bring more precise answers.
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Searching on aminet for “shutdown” I get quite a few results. One of them seems to address exactly your concerns. From the readme:

The Amiga’s lack of a shutdown mechanism is probably based on the assumption that the user is always the direct cause of disk access or at least aware of the fact that the disks might be accessed at a certain point. Unfortunately this is obviously not true … [and] there’s also still the small chance that the user thinks the disks are idle and it’s safe to turn of the system and a background program chooses this moment to start disk activity.

I haven’t tried it but it’s available here http://aminet.net/package/util/libs/shutdown

I’d be interested to hear from anyone who uses such a program.

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Yes, it probably is based on the assumption that the user is normally in total control of all disk accesses. If you were running a fileserver or similar it would be your responsibility to ensure that this task is topped before switching off power to the machine. If you forget to do that however, there’s always the risk of corrupting a file. Personally I think it would be good to have it as an option, but it should not be enforced upon users the way other operating systems do. That leaves it up to the user whether they avail of the feature or not.

Leaving opinion-based stuff aside (that sort of discussion is better left for the many Amiga forums), there are a couple of hardware and software solutions available for handling the safe shutdown of the Amiga. The newer Mediator models for example, support ATX power supplies and can turn them off via software, meaning you can have a shutdown menu item or similar to do the job. Earlier solutions used a pin on the parallel port to turn off a relay that cut power to the computer, again allowing you to shut down the computer with a single command.

One of the main reasons for having a shut down function is to ensure all applications save their work and quit safely before the computer power is removed. This isn’t possible on the Amiga as there is no standard method of letting applications know that the computer is about to be turned off. So, while some ARexx scripts might be used to close specific applications such as YAM, it’s not system-wide and won’t work for any applications not specifically added to the shutdown script.

A couple of things can be done to help this situation. First, the Amiga default filesystems are terrible at handling interrupted writes. Switching off during a write to a FFS volume will invariably result in the volume needing to be revalidated the next time it is turned on, and usually will result in corruption of the file being written to. SFS and PFS both use journaling to ensure this doesn’t happen and so makes it safer to turn off power without warning.

Hard drive partitions can be switched to read-only by using the Lock AmigaDOS command in a script. For example:

; Script for shutting down Amiga
Lock DH0:
Lock DH1:
Lock DH2:
Lock DH3:
Wait 2 secs

This script will ensure the partitions listed are write protected before power is cut. Any hardware-specific power down command can then be added to the end, and will be executed after 2 seconds. ARexx scripts for shutting down specific applications can be added to the start of the script. Without hardware shutdown capability it can still be used to secure the partitions before manually shutting off power, similar to old pre-ATX PCs.

This script can also be used with ResetHandler from Aminet (http://aminet.net/package/util/cdity/ResetHandler), which intercepts the reset signal (Ctrl-A-A) and allows you to make the partitions safe before the reset takes place.

The downside is that the script doesn’t protect volumes not listed, such as removable drives, floppies etc. An alternative might be the ShutAll tool from Aminet (http://aminet.net/package/util/cdity/ShutAll_1.01), which I have never used but is supposed to go through all the mounted volumes on the system and lock them for you.

 

The bottom line is that there is currently no way in Amiga OS to ensure it’s 100% safe to shut down, and even if such functionality was to be added in the future, none of the existing software would take advantage of it. The best that can be done is to manually ensure any data that needs to be saved has been, and then protect the drives in the system from being written to before powering down. Software control of system power is possible with additional hardware, but is basically the same things as pulling the plug, i.e. it does not protect the computer from corrupting files.

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