Subject: [nfsv4] FW: [FedFS] Meeting Minutes, 06/04/2009

From: "Everhart, Craig" <[email-masked]>
Date: Thu, 11 Jun 2009 13:40:26 -0400

I volunteered to draft some text for the effects of FSL caching in
fileservers.  James added an "fslTTL" value in the NSDB protocol
document "draft-ietf-nfsv4-federated-fs-protocol.txt".  Here's my text.

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Thus, to handle the effects of FSL caching, when a migrated fileset is
removed from a file server, it should be replaced by a junction
referring back to the NSDB entry for the fileset.  Thus, in the above
example, any fileservers A would direct clients to fileserver B, but
they in turn would direct clients to fileserver C.

Such supplemental junctions (on fileserver B in the example) would not
be required to be in place forever.  They need to stay in place only
until fileservers A should have invalidated their cached FSL entries for
the target fileset.  The NSDB protocol allows for the specification of a
"fslTTL" field, a count in seconds of the time interval which is an
upper bound for the lifetime of the cached information and a lower bound
for the lifetime of the supplemental junctions.

For example, suppose this field value contains 3600 seconds, one hour.
In such a case, administrators MUST keep the supplemental junctions in
place for at least one hour after the fileset move has taken place, and
FSL data MUST be cached by a referring fileserver for no more than one
hour without a refresh.
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		Craig