Re: [9fans] Clearing venti arena during install

[bakul+plan9@bitblocks.com]

> > If fossil+venti is chosen during installation, the entire
> > venti arena partition is cleared.  Is there a way to avoid
> > clearing all of the arena space?  Since in a sense it is an
> > append only log, and the purpose for clearing it is,
> > presumably, to allow recreating the index, may be a shortcut
> > exists?  Doing so will save a lot of time and space
> > particularly on a qemu VM.  In qemu one can use a sparse file
> > or a qcow format file which allocates space only for data
> > actually written.  Writing even zeroes can eat up space.
>
> Any sparse file worth its salt would catch the case
> where you write zeros to a hole and not do anything.

Creating a hole is as easy as seeking beyond the end of a
file and scribbling something but maintaining its holeyness
by checking every write for a block of zeroes is quite
expensive.

> That said, I'd rather leave the zeroing in for now.
> The new venti, which I am testing on Plan 9 right now,
> does not require the zeroing.

This is a much better solution -- I didn't realize this was
imminent.  Thanks!