Subject: [nfsv4] pNFS items for disussion at Montreal IETF

From: Garth Goodson <[email-masked]>
Date: Mon, 10 Jul 2006 09:36:50 -0700

I've summarized the current open issues and hope these can lead the pNFS 
discussion tomorrow.

Open Issues:
------------

* Issue #21: CB_SIZECHANGED discussion for block layouts - Owned by Fridella
   - Steve Firdella is in progress of rewriting proposal text.
   - David Black had some followup email.
   - Benny pointed out that it is required for objects (and files) in the
     case of a client knowing where EOF is when reading a sparsely
     written file.

* Issue #40: DS and MDS w/ different security mechanisms in use - Owned 
by Eisler
   - From Thurs wg call: This issue needs more discussion.  Is this when
     they both speak files? (yes) Will SECINFO changes in 4.1 will allow
     us to do this?

   Mike Eisler's text:

   For a given file object, a metadata server
   MAY require different security parameters
   (secinfo4 value) than the data server.
   For a given file object with multiple data servers,
   the secinfo4 value SHOULD be the same across
   all data servers.

   If an NFSv4.1 implementation supports parallel
   NFS and supports file layouts, then the
   implementation MUST support the SECINFO_NO_NAME operation,
   on both the metadata and data servers.

* Issue #55: Attribute for when to write through MDS to DS - Owned by 
Goodson
   - Have made two proposals, only heard back from Mark Eshel.
   - Anecdotal evidence that block size is also useful (from Dean
     Hildebrand in talks w/Natl. Labs)

* Issue #57: Private layout range - Owned by Goodson
   - I made proposal that new layout types be approved before becoming
     IANA types.  Mike Eisler asked if IANA really needs to be involved
     (I don't know).  Need to clarify experimental layout ranges.
   - Can't require WG acceptance as WGs are ephemeral, can require
     specification or expert review

* Issue #58: pnfs: layout return flag for fsid returns - Owned by Halevy
   - Benny Halevy sent text to alias, but would like to change proposal
     to use CURRENT FH.  Benny Halevy has concerns about the bigger issue
     about synchronizing gets and returns.  Benny says that Issue #19 is
     okay, but will continue thinking about the current issue and will
     write a proposal.

* Issue #61: Lingering writes (outstanding writes at time of a 
recall/return) - Owned by Goodson
   - Proposed text sent to WG list by Garth Goodson (no current
     objections)
   -  2 cases:
     - writes that are outstanding MUST be done by time client issues
       layoutreturn
     - if writes can be outstanding, server must fence those writes from
       completing.

* Issue #69: File layout striping structure - Owned by Goodson
   - Proposal sent to WG mailing list (last week)
   - Eshel wants to bring up the issue of clearing client device ID
     cache.

* Issue #70: pNFS chapters need significant editing - No owner
   - need to merge into v4.1 spec -- make things flow...

There was much discussion on the following issue regarding: RECALLs, 
RETURNs and GETs (not sure we need to discuss this)

   - Brent Welch wants concrete rule for what happens during the interval
     between the RECALL and subsequence RETURNS and GETS.
   - Noveck: proposed following text with the addition of the rule that a
     server shouldn't have overlapping recalls outstanding

      Use a do-one-thing-at-a-time model for voluntary layout
      returns, requiring LAYOUTGET's for the same file to be
      resolved before proceeding to do the voluntary LAYOUTRETURN.

      For recall-prompted LAYOUTRETURN allow you to synchronize only
      with LAYOUTGETs listed in the CB_SEQUENCE, with the understanding
      that client will not grant any subsequent LAYOUTGETs (those not
      in the CB_SEQUENCE) any region that overlaps that recalled.

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---

From: Benny Halevy <[email-masked]>
Date: Mon, 10 Jul 2006 14:11:58 -0400

Garth, in relation to issue 58 I'd like to propose adding RECALL_ALL and 
RETURN_ALL
flags to LAYOUTRECALL and LAYOUTRETURN, correspondingly.
These will allow quickly recalling and returning all layouts in cases 
like preparation for shutdown
or quiescing clients for snapshots.

Benny

Garth Goodson wrote:

> I've summarized the current open issues and hope these can lead the 
> pNFS discussion tomorrow.
>
> Open Issues:
> ------------
>
> * Issue #40: DS and MDS w/ different security mechanisms in use - 
> Owned by Eisler