Re: [9fans] fossil+plan9: disk full revisited

[Georg Lehner <jorge-plan9@magma.com.ni>]

I did it again!

on a second machine I tried

 dd -if=/dev/null -of=fillit.all bs=1024k count=2048

with a 1.8G fossil partition to be sure to fill it up completely.

I learned four things from it:

- fossil does not compress duplicated data blocks
- fossil cannot store total data bigger then its partition size
- read the documentation
- Read the Documentation!

The excelent paper:

  http://www.cs.bell-labs.com/sys/doc/fossil.pdf

tells it all, it's a pity it is not referenced in the papers section
on Bell labs Plan9 page.  You must instead go to the wiki and there to
the papers section.

I think the Plan9 papers section tend to confuse, since the "old" file
server is still referenced there although it seems more of historical
interest then as introductory material.

On the other hand my perception was biased by the installers
suggestion of the distribution of space between fossil and venti.

I have a 12GByte Harddisk, which was divided into:

  fossil    1.84G
  arenas    9.24G

considering that the filesystem gets compressed in venti, after some
thought I'd use as much fossil as possible and the smallest venti
possible for a reasonable archival time span (1 year?).  If venti runs
out of space one would archive some arenas to CD, DVD etc.

With a dumb estimate of 30% compression ratio one would give about 60%
of a disk to fossil, and 40% to venti.  What are venti compression
ratios experienced in real live?!


However I am not sure, if my conclusions are right. At

  http://www.magma.com.ni/moin/Plan9Tutorial/FossilVenti

my current understandings about fossil+venti are put together. I would
be very pleased to get feedback and corrections about it.

Regards


    Jorge-León