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Date:      Mon, 11 Mar 2002 08:22:16 -0800
From:      Terry Lambert <tlambert2@mindspring.com>
To:        Garance A Drosihn <drosih@rpi.edu>
Cc:        Poul-Henning Kamp <phk@critter.freebsd.dk>, Harti Brandt <brandt@fokus.gmd.de>, arch@FreeBSD.ORG
Subject:   Re: Increasing the size of dev_t and ino_t
Message-ID:  <3C8CD9B8.53D6B36F@mindspring.com>
References:  <17497.1015840078@critter.freebsd.dk> <p05101542b8b281472641@[128.113.24.47]>

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Garance A Drosihn wrote:
> At 10:47 AM +0100 3/11/02, Poul-Henning Kamp wrote:
> >(Sorry, I confused st_dev and st_rdev earlier).
> >
> >Ok, I think we are on the same page now.
> >
> >I don't think any of the stuff headed for -current would give
> >you trouble in this respect.  Just because we _can_ assign a
> >random st_dev doesn't mean we will shoot ourselves in the foot
> >by doing so :-)
> 
> Given what we (RPI) have with our present AFS cell, I am not
> sure how easy it will be to do this.  If you follow my previous
> description of AFS, you realize that RPI (by itself) has over
> 33,000 unique AFS volumes.  We also have users who will touch
> a large percentage of those volumes by typing in a single 'find'
> command.  If FreeBSD comes up with a unique random number for
> each volume as it is referenced, and it has to cache all the
> mappings between unique-numbers and AFS-volumes (so it can
> tell when the same AFS volume is found at a different pathname
> in AFS space), then that strikes me as an unwieldy situation.

Poul is a non-native English speaker, and this often leads
to intepretation issues.

The usage here is archaic English, and the "can"/"will" are
paired, which isn't clear from the use of the predicate
phrase "by doing so".

You should read this as "Just because we _can_ ... doesn't mean
we _will_ ...".

> Also note that the >33,000 number is only for the AFS cell at
> RPI, and the way AFS works any single workstation can be mounting
> volumes from more than 150 different AFS cells.  AFS is trying
> to create a world-wide distributed file system, and as such it
> sees scaling issues that no one faces with NFS.

This is a seperate problem.  As you note, the number is already
larger than 2^15; it's going to face scaling issues, no matter
how you look at it, due to the single volume identification
space.


-- Terry

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