Re: [9fans] growing/shrinking venti arena files -OR- arena file format

[erik quanstrom <quanstro@quanstro.net>]

> I'm wondering if anyone can shed some light on growing and/or shrinking
> arena files (i.e., disk partitions).  With the growing popularity of
> logical volume management, vitrualization, etc., resizing partitions is
> becoming more and more common, and many file systems already have
> "resize" tools or options to grow/shrink file system structures
> according to changes in the size of the underlying device.  I'm
> wondering what capacities (if any) venti has for dealing with inceases
> or decresases in the size of its arena files.

i'll be honest, i don't understand this statement of the problem.  the
venti abstraction has some answers for this problem.  so i would be disinclined
to look "under the covers" to start.

venti arenas are very small (~650mb) and fill in order.  so taking away empty
arenas should be no problem, while taking away partial arenas will lead
to data loss.  650mb seems like rounding error with today's storage, so
personally i would ignore the problem of resizing an arena.  alternatively,
if one has truely tiny storage, i would be tempted to start with very small
arenas, and still add or remove full arenas.  worst case, i think venti/copy
can be used to recover a deleted last arena to a smaller one.  but the temporary
storage requirements are a bit greater.

- erik