Richard Rauch wrote:

> On Mon, Nov 29, 2004 at 09:34:06PM +0000, Simon Truss wrote:
> 
>>Richard Rauch wrote:

> Here's an approximately descending-order list of my
> priorities:
> 
>  1 Eventually using all 240GB.
>  2 Not having to rebuild the filesystem from scratch
>    in order to use both drives in one filesystem later.
>  3 Reliability/redundancy of data/drives in the short
>    term.
>  4 Speed.
> 
> ...and then the wildcard:
> 
>  * Anything I might not have considered (there's always
>    something).

:-) yes the computer that writes the program you haven't
asked for yet.

>>vinum might be what you are looking for here. searching for
>>Logical Volume Manager or LVM should get you some hits.
> 
> 
> Okay, I've heard of that.  I never looked into it before.  I'll
> have a look at it.  (^&
> 
> If it lets me do #3 in the list above, and then eventually
> give up #3 and get #1 and #2, then that's just what I need.

an LVM should get you 1 and 2, 4 should not get you any penalty.
3 is not addressed by LVM, only RAID or backups. RAID will get
you 3 and 4. I may be wrong here but I think only jfs and xfs
enable extension of a live file system (linux).

If you were to accept a read only filled drive when you add the
second, a cheap and cheerful option is the union fs (mount_union).
There are some neat file systems in NetBSD. The loopback file
system might also be worth a look. If these more limited
options suit, they would probably scale more easily.

Having almost lost a 1TB file system recently I am thankful I
placed reliability on the core components high on my list.
Even so, the only survivors in the system were N-1 of my discs
and the RAID card! My previous server after many years and many
discs just wasn't up to it (P133) and NetBSD 1.0 upgraded many times
also.

Its nice, I can actually answer some questions on this list :-)
Thanks.

Simon