[RC5] Checkpoint file

TimO hairballmt at mcn.net
Thu Oct 25 00:18:01 EDT 2001


Dennis Lubert wrote:
> 
> At 18:36 24.10.01 -0500, you wrote:
> >| -----Original Message-----
> >| Well, this all sounds good, but it doesnt help much. the
> >| clients can't have
> >| all their own buffer files, because I run them from my home
> >| dir, which is
> >| NFS mounted in the network, so they use all one buffer file.
> >| so I wanted to
> >| set them up, with everyone its own checkpoint file.
> >| i also cant run a perproxy, and this wouldnt also avoid that
> >| the work after
> >| a few hours for the single machines is lost.
> >|
> >| for better understanding : its a university network, and I am
> >| allowed to
> >| run the client over night there sometimes, but with my
> >| account I have only
> >| my (NFS-mounted) home directory available
> >
> >You *can* have separate buffer files, using the technique someone else
> >mentioned of separate config files.  As long as you are setting up a
> >config file per client, set each config file to use a unique checkpoint
> >file.
> >
> >Where buffer files are iffy, shared checkpoint files are absolutely not
> >an option.  The client assumes it owns the checkpoint file, and rewrites
> >it every time the work in process is saved.  If you are using checkpoint
> >files, you *must* guarantee that each client is using a separate config
> >file.
> mh, well can this be done with the -ini option ? mh, I will look if theres
> an option for checkpoint files, because its not fun to set up 138 different
> ini files... I use a script to start them all via ssh, so I could use the
> hostname as name for the checkpoint file, that should be unique
> 
> >A clean shutdown of a client will result in all work being saved
> >properly, checkpoint or not.  The checkpoint file is really intended to
> >protect against unexpected shutdowns.
> but afaik thats not true if several clients use the same buffer file. then
> only the last work unit will be used, all others discarded, so everything
> not finished then will be lost....
> or am i wrong ?
> 

You need unique config files and/or unique buffer/checkpoint files for
each client.  You said that you want to keep network traffic down, so
checkpoint files aren't a very good option for you.  dnetc -shutdown,
^C, and killall(Linux anyway) dnetc will all save current state if you
have unique buffer files for each client(as specified by unique config
files).  Hitting the 'reset' button, pulling the plug, any other
catastrophic loss of power, or kill -9 pid_of_dnetc are the most common
instances which would make a checkpoint file handy.  How often do those
occur?  Having unique buffer/checkpoint files requires you to have
unique config files for each client.

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-- TimO
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