Re: [9fans] Ideas for gc on venti

[Bakul Shah <bakul+plan9@bitblocks.com>]

On Wed, 18 Jun 2008 22:57:27 +0200 Enrico Weigelt <weigelt@metux.de>  wrote:
> * erik quanstrom <quanstro@quanstro.net> wrote:
>
> > it makes sense for the storage managment function to present an
> > idealized block device while hiding details like disk replacement
> > and redundency.
>
> Well, I intend to make venti the storage device itself
> (eg. in form on an hw appliance ;-P). At this point an special
> venti could make hw RAID obsolete and also do things like bad
> block handling.
>
> RAID has some disadvantages, eg. you have to nail-down partition
> sizes and it's not trivial to resize or move around volumes.
> A venti-based system (which maybe presents an block device via
> venti) can make runtime configuration much easier.

Have you looked at zfs (on solaris, freebsd or macos)?  It
seems to offer most of what you are looking for.

As for venti, you can use something like venti/copy to copy a
subset of trees to a new venti and then reuse all of the old
venti space. This is exactly like a copying GC (only "live
data" is copied). But why bother.  For one thing you can't do
selective file copying without a lot of extra hassle.