Re: NFS V4 attributes proposal

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From: Conrad Minshall (conrad@apple.com)
Date: 12/01/98-01:47:19 PM Z


Message-Id: <l03130300b289f11e7b82@[17.202.43.185]>
Date: Tue, 1 Dec 1998 11:47:19 -0800
From: Conrad Minshall <conrad@apple.com>
Subject: Re: NFS V4 attributes proposal

At 6:43 AM -0800 12/1/98, Mike Eisler wrote:
>> At 4:34 PM -0800 11/29/98, Robert Thurlow wrote:
>>
>> >3) Extended attributes
>>
>> >Support for extended attributes shall be optional but recommended.
>>
>> Why optional?  This capability helps NFS be the transport for several
>> important filesystems.  Extended attribute capability already exists in
>> Microsoft's NTFS http://www.mvps.org/win32/ntfs/index.html, in HFS+, the
>> new file system format Apple introduced with MacOS 8.1, and in UDF
>> http://www.osta.org/html/ostatech.html#udf.  (UDF is used with the various
>> DVD formats.  Grossly over-simplifying, UDF can be thought of as the next
>> generation, read-write ISO 9660.)
>
>If we make it a MUST, then that means that if I stick a DOS floppy with a FAT
>file system image into my box, I can't provide NFS V4 service over it.

Maybe this isn't a binary decision.  At least three possibilities exist:
  1) v4 implementations shall provide extended attributes on all sorts of
filesystems.
  2) v4 implementations shall provide extended attributes for all
filesystems which themselves provide extended attributes.
  3) v4 implementations need not provide extended attributes.

#1 is undesirable, yes.  It may be *possible* to represent extended
attributes over any underlying filesystem but then you have a filesystem
interchange incompatibility problem.

#3 is how I read Robert's proposal.  I much prefer #2, as then systems
which have APIs to use filesystem extended-attributes and support version 4
NFS will allow use of those extended-attributes over NFS.  Local/remote
transparency is retained.


--
Conrad Minshall ... conrad@apple.com ... 408 974-2749
Apple Computer ... (Mac OS X) Core Operating Systems ... Filesystems & Kernel
Note if "conrad@apple.com" doesn't work, try using rad@acm.org.
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