On Thu, 15 Aug 2002, John Koenig wrote:

> Yup... after I deployed a 181 GB drive for our holding disk, I saw
> somewhat different behavior in amstatus... though I would have
> expected the total time of the backups to drop (compared to a
> relatively small 25 GB holding space I used before) they did not... I
> conclude this was because the entire run is tape i/o bound... Holding
> disk usage on the runs with this disk were about 90% capacity... so
> the clients were not taking so long to complete their data
> transfers...
>
> This would seem to indicate I need to double this amount of space to
> hold 2 days of backups, currently... I'd like to have a week's worth,
> actually.... in case the tape goes South and replacement is not easy
> and quick.
>
> So does the chunksize parameter affect performance in any way?

No.  Taping of a dump spooled to holding disk does not begin until all
chunks are received.

The best way to figure out where your bottleneck and what configuration
changes will give you the greatest return is is to run amplot.  It will
give you a graphical representation of what's happening when.  Very
revealing.

-Mitch