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RE: Review of quota-06

From: Jim Whitehead <ejw@soe.ucsc.edu>
Date: Fri, 18 Mar 2005 17:13:59 -0800
Message-Id: <200503190114.j2J1E2QL001421@services.cse.ucsc.edu>
To: "'Julian Reschke'" <julian.reschke@gmx.de>
Cc: <w3c-dist-auth@w3.org>

Julian Reschke writes:
> I think it would be a useful feature if a client could detect 
> whether a write failed because of disk full rather than quota 
> exceeded (Unix and
> NFS4 status codes allow the same distinction, see RFC3530, 
> "NFS4ERR_DQUOT" and "NFS4ERR_NOSPC").

So, if I understand you correctly, you're advocating the addition of a
single additional error code to cover the storage media full case?


> I'd like to understand why it's only optional on non-collections.

Seems to me this is obvious. There are four cases:

1) No support collections, no support others: You don't implement the
specification

2) Support collections, no support others: Frequent case, collections have
quota information

3) Support collections, support others: Possibly frequent case, all
resources give quota and used

4) No support collections, support others: This case isn't allowed in the
specification, but seems unlikely to me, since collection support is so
useful


So, is it that you think case #4 is useful, and want it to be allowed? Or
are you seeking clarification text to be added to the draft?

 
> So for a server that implements user-based quota (which IMHO 
> is the most common way to implement it), DAV:quota-used-bytes 
> usually will be the
> *same* for a collection and it's members.

Ah, good point.

Let me try again with some suggested text (the second paragraph is new, and
based on your previous text):

"Since there are many factors that affect the storage used by a set of
resources, including automatic compression, the size of associated metadata,
and server-inserted content (such as that created by PHP code) in the
on-the-wire representation of resources, clients are advised to not depend
on the value of DAV:quota-used-bytes being the sum of the
DAV:getcontentlength properties for resources contained by a collection. 

Additionally, because there may be a number of distinct but overlapping sets
of resources for which a DAV:quota-used-bytes is maintained (see Section 4),
there may be no correlation between the size of the resources in a
collection and DAV:quota-used-bytes. For example a server that implements
user-based quotas, DAV:quota-used-bytes usually will be the same for a
collection and it's members."

If you have quibbles with this text, please suggest modifications to it in
spec. language (it's easier than reading your mind :-)

- Jim
Received on Saturday, 19 March 2005 01:14:19 GMT

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