[Dirvish] Per Vault Expiry

Keith Lofstrom keithl at kl-ic.com
Mon Dec 27 09:24:24 PST 2004

On Mon, Dec 27, 2004 at 09:53:13AM -0800, Steve Ramage wrote:
> Asked this a while ago on Dirvish Users
> Is it possible to set per vault expiry patterns, as for instance my USB 
> drive isn't gaurenteed to always be there, so I would like to have the 
> backups expire less aggresively

This is a great idea!  Steve, could you write this up as a
RequestForEnhancement on the wiki, as well as pursue it here (two paths
in parallel).  Keep in mind that enhancements occur because someone 
volunteers to specify, code, test, review, and document them;  you
will have to convince a coder or do it yourself.  Since some folks
here prefer to just code, if you do a careful specification and later
perform the cross-platform testing, you are a lot more likely to get
what you want.

Without looking at the code, a syntactically compatable extension might
be to allow an optional additional field to the expire rules that gives
the vault to which it applies, such as:

        *       *       *       *       *       +3 months
        *       *       *       *       1       never
        *       *       *       *       *       never:usbvault

But lets look at the dirvish-expire code and find the easiest way. 
Also, look at "man 5 cron" and "man Time::Period" for more ideas.
We have a lot of choices of syntax here;  let's choose something that
is easy to code, and permits additional extensions in the future.

Steve: in the mean time, once we fix the problems you are having with
multiple backup images, the easiest thing for you might be to just not
expire, or expire very leniently.  If the hard linking is working
correctly, the additional images take up small amounts of additional
disk space. 

For example, I have about 100GB of stuff to back up, and some of my
drives have 100 images stored in 150GB total.  It may take a long
time to fill up my 250GB drives.  My plan has been to just retire the
backup drives to long term storage after they fill up, or after a year
has passed, without running expire at all.  OTOH, if we are about to
start tweeking on dirvish-expire, perhaps it is time for me to start
doing dirvish-expire myself, in order to participate in the testing.

Also, it helps a LOT to use a Reiser 3 file system on your backup drive,
because of its efficient use of space for directories and small files.
Some people say there are reliability problems with Reiser 3 (start
another topic!) but I have not seen them.


Keith Lofstrom          keithl at keithl.com         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs

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