Re: [9fans] fossil+venti backup question

[erik quanstrom <quanstro@coraid.com>]

On Thu Mar 29 08:07:40 EDT 2007, bituman@enerla.net wrote:
> The servers gonna be on 2 UPSes on different power circuits, but ISP 
> staff seems to have a weird sense of humor, one time they simply pushed 
> the power button on one of our servers.
> The place is supposed to be as safe as possible, and i'd like to have 
> the data on mirrored raid discs.
> I am mostly worried about users deleting files etc..
> I need previous versions of files, and if the user by mistake deletes 
> them, then i should be able to restore them.

you can get sort-of mirrored raid with fs(3).  it will
behave differently from a typical raid device.
intraspection of the device and no degraded state.  also
if you have a mirror of [m0m1] and [m0] fails, then reads 
will work but writes will fail.  typical raid mirrors would
report success in both cases but the raid would be put
into a degraded state.  also there's no support for rebuilding
the mirror if you replace a disk.  you need to do that by
hand.

while it's a bit different than you may expect, it might
be fine for you.

i think you could run without venti on a mirror of 
cat'ed disks (fossil wants a single partition.) by setting
your snap time properly and allowing snapshots to
live for a relatively long time (100 days).  you could even 
periodicly take an archive with vac onto a venti, without
depending on venti for day-to-day operations.

your best bet is probablly fossil+venti.

- erik