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Re: Request for cooperation with all burn backends

scdbackup@gmx.net wrote:


Joerg Schilling:
Cooperative locking is needed in a way that allows and is based not on
device nodes but on real hardware targets.
Bill Davidsen:
I'm less sure about cooperative locking, any method which fails if any one program behaves badly is not scalable.

It seems to be a hard constraint in the burn community
that the locking mechanism has to allow free access to
the drive if the burn program deems its actions harmless.

Full responsibility has as precondition a sufficient
knowledge of the situation, nevertheless. So the burn
programs need at least some means to announce their disturbance-sensitive activities on a drive and to detect
such announcements before starting any activity which
assumes exclusive usage of the drive.

A perfect solution also must address locking of
partitions vs. locking the entire device.

Partitions with burner programs ? How do partitions apply to us ?
Unless you believe that we can get device locking in for just one device and ignore the rest, a proposal would have to address locking the device for all devices, disk, tape, burner, flash, etc. I doubt that a partial solution would find much support, while a solution over all device might.

SysV message queue

msgget, msgsnd, ...
Indeed a candidate. Installed on my Linux.

Then there is mq_open, mq_send, ...
Labeled "POSIX". Not installed on my Linux.

I will consider to use this.
It has not the advantage of TCP/IP to detect the demise
of a lock holder by the end of the connection.

Have a nice day :)


bill davidsen <davidsen@tmr.com>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979

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