Coda File System

Re: Filesystem replication or expansion

From: Jan Harkes <>
Date: Thu, 4 Sep 2003 14:10:26 -0400
On Mon, Sep 01, 2003 at 06:46:35PM +0200, Cyril Bouthors wrote:
> At this time, we have 64GB and 3.3M Inodes used on our ext3
> filesystem.  We are hosting websites: mostly PHP scripts, images, few
> videos.  I think the biggests files are around 100MB.

There is no such thing as a hardcoded limit on the amount of space on
the server that can be exported. There is however a very realistic limit
on the amount of filesystem metadata than can be stored in a 32-bit
address space (i.e. RVM).

All the numbers you find (i.e. the 25GB server limit) is based on the
assumption that files are on average 16KB, and typical file/directory
distributions as found in surveys of UNIX systems in the late 80s/early

i.e. take them with a grain of salt.

As you can see from the example, 40MB of RVM is needed to store the
metadata of 50k files and 5k directories. With an average filesize of
50k this is equivalent to 2.5 GB of data.

Now if we plug in your current numbers. 3.3 million files (and I'm
assuming 33k directories) would translate into 1668 MB of RVM, which is
definitely stretching it for a single Coda server. Although 32-bit would
allow for up to 4GB addressable space, we do have to share it with
'normal memory usage' i.e. reserved for kernel, libraries, stacks, heap
etc. so more realisticly I would aim for 0.5 to 1 GB RVM which in your
case would probably be about 2 million files which translates into
approximately 32GB of exportable space per Coda server process.

Received on 2003-09-04 14:12:06