Howto do SW RAID?

[Pete French]

> I must say, ZFS sounds very cool, yet.... the experimental thingy  
> attached to it is somewhat off-putting at present. I noticed a remark  
> about the kernel memory tuning possibly being hasslesome. I'm not  

None of those things are true anymore on the latest -STABLE and amd64.

I use a ZFS based machine for backup, much as you describe. Nightly rsync
and continuous stream of data to a mysql slave. ZFS gives you the distinct
advantage of being bale to sake snapshots - so I have dailys for
the last 5 days, and I keep the sunday one of those as weeklies going back
as far as I have disc space for. All online and not actually taking up
any significant space as snapshots will only use disc space for the changes.

If you are clever with symobilc links you can even arrange it so your
database snapshot is actually online inside your mysql linstance. One
of my machine has the live database, plus 'live-7am', 'live-9am',
'live-11am' so if people make a mess of a table then they can grab the
data from no older than two hours ago instantly

"insert into live.table_i_screwed_up select * from live-9am.table_i_screwed_up;"

Given your system I'd acquire a 3rd drive (4 gig flash card will do) for
boot and then make a ZFS mirror our of the existing two and stick
everything significant onto that. It works very nicely indeed.

-pete.