Coda File System

Re: rvm data

From: Jan Harkes <>
Date: Fri, 3 Nov 2000 12:15:46 -0500
On Fri, Nov 03, 2000 at 11:56:01AM +0100, Simon Josefsson wrote:
> Jan Harkes <> writes:
> > > Is there a solution to this problem, or is coda not suitable for
> > > larger data sizes?
> > 
> > In any case you need a lot of swap. But when the RVM data is in a file,
> > it is possible to enable the use of private mmaps. This allows for a
> > huge improvement in startup time, as unmodified RVM-data pages are
> > simply discarded and re-read from the underlying RVM data file when
> > needed. Only modified pages are `dirty' and will be written to swap when
> > there is memory pressure. The swap footprint of a Coda server will
> > slowly grow over time during the lifetime of the server.
> This looks promising, how do I enable private mmaps?  I searched the
> documentation but didn't find anything.  Do I need to modify the code?

Either use the command line options -mapprivate, or add the following to

# Enable private mmap of RVM data.
# On Linux it is not possible to mmap of a partition, so RVM data has to
# be a file.

> Thanks for your explanation regarding rvm data size, I'll do some more
> testing to see how much I really need.

Volutil has an option that might prove to be useful while testing this,
it can query the exact amount of RVM data used by a volume.

    $ volutil -h server1 rvmsize 0x7f000524
    V_BindToServer: binding to host server1
    Volume 7f000524 used a total of 1176368 bytes.
	    4360 small vnodes used 488320 bytes.
	    54 large vnodes used 55512 bytes.
	    and 583680 bytes of DirPages.

small vnodes are files, large vnodes are directories, and DirPages are
the allocated directory contents. This happens to be the volume that
stores my incoming email in maildir format, and the combined size of all
the email (taken from cfs lv) is 41981 KB, so the average filesize is
relatively small, only about 9KB.

Received on 2000-11-03 12:30:47