Greg Troxel schrieb:

> Amanda reports a wide range of tape write speeds during actual backups
> and flushing, and I can't make sense of them - some of them seem too
> high by a factor of 8.

You mean the output of amstatus? No, there are no tape rates afaik, so
you mean the report email?

> Doing dd of a 8.5G file (2G ram, dumped several days ago, so could not
> possibly be in the cache) to /dev/null gets me 42.3 MB/s.  The raw drive
> gets me 67.8 MB/s.
> 
> This was all without another process writing dumps.
> 
> So for LTO-2, regular drives seem just barely ok.  For LTO-4 I wouldn't
> be so sure, as I think that needs 80 MB/s minimum.

My main problem seems to be the concurrent writes of the dumpers versus
the read-processes of the taper ... :-(

Right now I have a RAID0 over two LVM-LVs which still doesn't perform
good enough. I will repartition the drives to get two plain
Linux-raid-partitions without that additional LVM-layer I have right now
(it was simpler to try it this way first ...). Maybe that helps a bit.

An additional fact is that these two disks also contain DLEs to be
dumped so with amdump I get some traffic between LVs ... which also
decreases performance