[OpenAFS] AFS file-number, volume-size limits?

[R. Lindsay Todd]

Eben,

    I see others have answered you about file numbers, which is not 
something I knew.  But as far as the maximum size of a volume: There are 
fields in the volume structures that store the number of "blocks" a 
volume occupies, or may occupy (quota).  A block is 1K bytes.  These 
fields are 32-bit signed integers (or just "ints").  This sets a firm 
maximum size of a volume of about 2TB (1024 * 2^31).  This is theory, 
not practice!  But I don't see anything else that would limit a volume 
size, other than the practical problems of slugging this much data 
around moving volumes.  But I doubt such large volumes get moved too 
often.  Backup and restore are probably also issues.

    I suspect the "8GB" limit is someone's notion of a practical limit 
for moving volumes around, or maybe at one time there really was a 
historical limitation.  In any case, it is myth now.

    Someday soon the 2TB limit will need to be removed.

/Lindsay

-- 
R. Lindsay Todd                      email: toddr@rpi.edu
Senior Systems Programmer            phone: 518-276-2605
Rensselaer Polytechnic Institute     fax:   518-276-2809
Troy, NY 12180-3590                  WWW:   http://www.rpi.edu/~toddr

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