UPDATE: .nfsXXX files

From: Craig Ledbetter (cledbett@homeaccount.com)
Date: Mon Nov 11 1996 - 07:30:01 CST


I stand corrected:

Stephen Harris <sweh@mpn.com> wrote:

Craig,

It truely isn't needed.

With normal file system semantics (ie a local UFS disk), if you delete a
file that is open, then the filename is deleted, but the file itself
isn't
fully removed until all "opens" are closed on the file. With NFS you
can't
do that, so the renaming to .nfsXXX is a close approximation. When all
processes have closed the file it _is_ unneeded (on the local disk the
file would be finally removed), but there is no way for the server to
know this, so we cheat and assume that any .nfsXXX file over 7 days old
is unused :-)

rgds
Stephen

and,

Joe Pruett <joey@q7.com> wrote:

those files only exist in a very specific circumstance. when a remote
system (one that has the file system mounted via nfs) has the file open
and that same system unlinks the file. the client knows that it still
needs the data, but the name is supposed to go away so it renames it to
the .nfsxxx file. when the process that has the file open exits, the
remote system should then remove the .nfsxxx file. but if that system
crashes, then the file won't go away. if some other system deletes the
file while a system has it open, then the original client will get an
error when it tries to read the file again.

so generally, if those files are old then no one really cares about
them,
but you could have a long lived process that is working on a "deleted"
file.

Thank you for the corrections.

Craig Ledbetter
Systems Engineer
Home Account Network Inc.
cledbett@homeaccount.com
http://www.homeaccount.com



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