[OpenAFS] Write-through/delayed-write support in AFS?

[Derek Atkins]

Sandeep Gopal Nijsure <nijsure@cs.unt.edu> writes:

> Hi,
> 
> I am thinking to migrate from NFS to AFS for a small network, mainly
> because of security concerns. I am some concerns about losing the file
> modifications, due to the write-on-close policy of AFS.
> 
> 1. Do all the usual utilities like vi, Lyx, Emacs, Xfig etc. issue the
> close system call for the File->Save option (or do they use write?),
> or atleast on all the files before they exit?

They should.  At least vi, Emacs, xfig all work with AFS without
any issue.  If all else fails, all Unix Oses will issue an implicit
close() on application exit.

> 2. What if the users of the network use write file operations in their
> programs, and forget to close the files before exiting? Just like the
> OS closes the local files left open by the application, does it close
> the AFS files?

Same thing -- the OS will implicitly close the file on application
exit.  So long as the user still have valid tokens when the app
exits, all will be fine.

The only caveat is if they have a long-running app that does not close
their output file, they might not get to see the output from another
machine.

> If the concerns are real, is there any AFS support for Write-through
> or delayed-write (as used in NFS)? Performance penalties is not a
> concern.
> 
> Any help will be greatly appreciated.
> 
> bye,
> Sandeep

-derek

-- 
       Derek Atkins
       Computer and Internet Security Consultant
       derek@ihtfp.com             www.ihtfp.com