Coda File System

Re: Coda And Samba PDC Server

From: Jan Harkes <jaharkes_at_cs.cmu.edu>
Date: Fri, 19 Dec 2003 12:02:56 -0500
On Fri, Dec 19, 2003 at 04:17:42AM -0500, Ivan Popov wrote:
> >     $ rvmsizer ~/coda-HEAD ~/coda-HEAD-obj
> >     total directory size   1220608 bytes (1.16MB)
> >     estimated RVM usage based on object counts, 739024 bytes (0.70MB)
> 
> The "total directory size" is for some reason remarkably bigger than the
> (total!) calculated RVM usage. As it is just what stat() says about the
> directory sizes, it does not have much to do with the internal
> representation, but still a bit strange.

That was an interesting observation, so I decided to dig a bit.

It turns out that I use ext2 with a 4KB block size. As a result the
minimal directory size is 4KB and uses 4KB increments. Coda directories
in RVM consist of 2048 byte 'pages'. Most directories in the trees I
looked at fit in a single 2KB page, a couple use 2 pages and two even
needed a third page. Coda uses just over 330KB to store the directory
data.

It does look like the counted total directory size is approximately
double of what I would expect. There are only 148 directories which
adds up to only 592KB. Don't yet see why we seem to be off by so much.

Jan
Received on 2003-12-19 12:05:00