From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] venti block score & type
In-Reply-To: Your message of "Thu, 11 Dec 2003 17:22:10 PST."
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From: "Russ Cox" <rsc@swtch.com>
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Date: Thu, 11 Dec 2003 22:15:18 -0500
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> Am I write in assuming that both the score and type have to match for a
> successful venti block read?

Yes.

> Similarly, that attempting to write a block whose score is already in venti,
> but with a different type, will fail?

No.  A new index entry will be written for the new type.

Types are really just to help a little in interpreting the
data.  They're almost purely advisory.  (Almost, because
the answer to your first question is yes.)  Since blocks are
zero-truncated before storing, the zero-length block
might reasonably be interpreted as a data block or as
a pointer block of any depth.  Similarly, if I store a file
whose contents are the SHA1 hash of a small file, that
contents will be stored as data, but storing the small file
itself would use the same block as a first-level pointer
block.

Russ