Hi All

trying to setup my two tape units (dds3 autoloaders) and noticed a few
problems I have run into on the amanda.conf.

for my tape dev I will understand the 

tapedev "rait:{tape:/dev/nst0,tape:/dev/rmt2,null:}"

but what would the rawtapedev be and also the changerdev.

Hope some has these answers, being to new to amanda.

regards

Joseph

On Tue, 2002-11-12 at 03:53, Marc Mengel wrote:
> Frank Smith wrote:
> 
> >>Hi All
> >>
> >>I have two dds3 tape changer units and would like to know if amanda can
> >>use both of these units simultaneously. Can I do some sort of raid
> >>backup across two tapes in two different machines of just use two tape
> >>units at once.
> > 
> > 
> > I think the latest (2.4.3) release lets you stripe or mirror across
> > multiple tape drives one one machine (I remember reading it was a
> > feature of the betas, don't know for sure if it stayed in the final
> > release).  I don't think taper will write two different dumps to two
> > drives simultaneously.
> 
> Right.  With the 2.4.3 code you can stripe accross drives, set your
> tapedev to "rait:{tape:/dev/rmt1,tape:/dev/rmt2,null:}"
> which will do a RAID-4 stripe of the two tape drives and write the
> parity blocks to the null tape device.  This should give you roughly
> double the throughput and capacity, if your I/O isn't bottlenecked
> (on some configurations and some drives you need to have the two
> drives on their own SCSI bus to get double throughput; not sure about
> DDS2...)  In this configuration you always need both tapes to be
> able to read a backup.
> 
> If you want a mirrored tape, its "rait:{tape:/dev/rmt1,tape:/dev/rmt2}"
> or more abreviatedly "rait:tape:/dev/rmt{1,2}", then you get two copies
> of the tape.
> 
> Had you a third drive, you could do the 3-way RAID-4 stripe, and you could
> read the backup with any two of the 3 tapes in the event of tape failure.
> 
> Marc
> 
>