Re: shadow sets, cluster, merge, MVTIMEOUT, dismount

Phillip Helbig---remove CLOTHES to reply wrote:
I'm not sure. If you are already shutting down the system, then I think
you can go ahead and dismount disks which SHUTDOWN.COM will not
dismount.

Then you basically have to perform all the tasks in shutdown.com in
syshutdwn.com ... re-invernt the wheel.

For instance, the INSTALL PURGE is done very late in the shutdown code.
You would have to do it yourself in syshutdwn.com to make sure you've
cleared all your disks of installed images. And you need to stop the
queues as well etc etc etc.

In general, yes. In practice, installed files and page and swap files
are taken care of by SHUTDOWN.COM, at least if they are on the system
disk, maybe if they are elsewhere as well.

This is done much later in the shutdown once all processes have been
killed. But even then, you have no assurance that the process running
shutdown.com is mapped to a page file on the system disk. You would
have to do a shutdown by first using sysgen to remove any additional
pagefiles, and then spawn a detached process that runs the shutdown
procedure (this one would be mapped to a page file on teh system disk
since all others have been marked for delete).

Then, you could kill all other processes except yours, and this would
give you reasonable assurance that the pagefiles on non-system disks
would be closed and you could then succesfully dismount it.

My concern is with shadow sets with members directly connected only to
the node shutting down, and with members of shadow sets one member of
which is on the node shutting down.

The concern is the ability to have a disk that *can* be dismounted, as
opposed to being marked for dismount. To avoid any merge/copy, you need
to cleanly dismount the shadow set istead of removing a member from a
surviving shadow set. And that means that you need to shutdown all
applications that use that shadow set on ALL nodes in the cluster.

It also needs good design in terms of page/swap file locations so that
you can cleanly dismount disks without having to cull processes all over
the cluster.

Indeed. On the other hand, most of the work is cleanly shutting down
the applications. After that's done, I hope the code I just posted will
do the trick. :-)

Suppose two applications require a shareable image to be installed. Both
startup procedures can do an INSTALL of it (first testing to see if it
is installed), but when you shutdown, one cannot remove the installed
image because it might sill be needed by the other application so it
isn't as obvious.
.

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