You've put your finger exactly on another concern that I
had been thinking about. If you are doing a bunch of in-behalf
mounting, then every access is going to result in a mount
charge, which you have to know to expect because you are not
notified. If you do a bunch of copies, then you are going to get
hit with a bunch of charges which would not happen if you were
signed into said 20, using NFT and explicitly managing the mounts.
It seems to me that it would be a good idea to issue some kind of friendly message that this happened. I don't immediately known how to do that with DAP (I do with FTP and Kermit). At a minimum you might want to set your user's expectations to let them know that they are getting charged for all this 'friendliness', maybe with training or some introductory email.
Right now, I'm working on wildcard searches that have to mount
structures when they come into scope, and dismount when the
wildcard goes past the structure. Tops-20 allows a limited form
of this (viz, DSK*:), but doesn't
generalize structure wildcarding like Tops-10 does (which I have
always thought an odd limitation).
The hidden charging problem doesn't quite happen in FTP because
it is explicitly known as you must issue an SMNT
to get a structure mounted. What's interesting is that RFC959
never specified a verb to do the structure dismount, which you
would want to do to save the charges if you got billed for the
duration of the mount. I'm pretty sure we charged for that.
If you want to use a couple of structures, then you are incurring
online charges for all of them at once because there is no way for
them to get released until the FTP session terminates. Unless
... Your FTP happens to support the DSMT
verb, which I explicitly created for this purpose, way back when
(and still have to get off my butt to put into an RFP).
You might be able to get tape mounts to work, at least on Tops-20 (and if so, probably Tops-10). Tape mounts on Galaxy can be quite transparent, provided you are using labeled tapes. If the right one is online and you are using automatic volume recognition (AVR), you would specify the tape label as the device and the tape gets automatically mounted for you with the label as the logical name, which parses exactly like a device.
In other words, tape FOO shows up
as psuedo-device FOO:. It's not
quite a hack, but perhaps close enough. You can also specify the
tape to not auto-dismount, so it would stay on the drive still
ready with the same label for you to use again. I repeatedly used
this when debugging a batch job to write a Kermit tape. The tape
just stayed on the drive while I kept trying to get it right...
On 4/15/23 8:11 PM, Johnny Billquist wrote:
Thinking a moment further, I should perhaps expand a bit on this...
So, mounting of tapes are always non-shared (for obvious reasons). So, if someone mounts a tape, anyone else trying to do anything with that device is just going to be hanging until the first user is finished with the tape and dismounts it.
Disks on the other hand can be mounted shared. However, unless mounted public, each user needs to mount the disk in order to access it. (So yes, a disk can be mounted multiple times, by multiple users/sessions.)
Now, mounting is actually associated with a logged in session (or more specifically a terminal). If you mount something, it remains mounted until you explicitly dismount it, or you log out, at which point it is forcibly dismounted.
This is basically incompatible with how DAP works, where you basically access a file for the duration of that connection. And one connection usually means open a file, do various operations, and then close the file. So if you copy two files from one system to another, it is two independent sessions as far as DAP is concerned.
So there is no way to access content on a not-mounted device via DAP. How would that work? If you were to be able to request a mount, it would be associated with a logged in session, but in this case that don't exist (unless we talk about the session on the remote system).
So if you were to mount, at the end of the mount request, there would be an implicit forced dismount again. If the next thing you wanted to do was to copy something from the mounted device, it would already have been dismounted again, and content would no longer be accessible.
Basically, in RSX, you are only able to access content on publicly mounted devices for this reason.
Johnny
On 2023-04-16 02:01, Johnny Billquist wrote:
Mounting in RSX is pretty much identical to VMS.
And there is no way to mount things over DAP as far as I know. But I'd be interested in any information related to that.
Johnny