[12084] in Athena Bugs
Re: sun4 7.6R: inc
daemon@ATHENA.MIT.EDU (Marc Horowitz)
Wed May 25 20:20:36 1994
To: epeisach@MIT.EDU
Cc: bugs@MIT.EDU, sybok@MIT.EDU
In-Reply-To: [12083] in Athena Bugs
Date: Wed, 25 May 94 20:20:15 EDT
From: Marc Horowitz <marc@MIT.EDU>
>> You are neglecting that for every file you create, you must also
>> allocate an inode which takes up space.... I forget if the inode,
>> which is a block of data giving pointers to the other blocks in the
>> file, is 512bytes or 1K (this is based on the size of the filesystem
>> your data resides).
Actually, this isn't quite right. Quota counts data blocks; inodes
are stored somewhere else. The inode contains space for 12 disk block
addresses. If you have more blocks than this, then the system will
create "indirect blocks", which are normal disk blocks containing
the additional disk block addresses.
Under UFS, an empty (zero-length) file doesn't use any space at all.
(AFS seems to hit you for 1k of quota for a zero-length file, though.)
However, any data you do have is rounded up to the nearest 1k. This
applies for both UFS and AFS. This latter detail is probably what
causes the difference between 41k and 50k, especially if you have a
bunch of short messages.
Marc
