We just finished DUPPING a 4 volume LTO5 set, 37 hours, 10+ hours per volume.
We have a 4 fiber drive library, so we could accomplish this without impacting daily saves, dups, etc. (had to change/move a few jobs)
Previously, with our old 2 LTO3 fiber drive library, this could not be done.
A previous support call with IBM, IBM has confirmed the DUP command has performance issues (16 buffer maximum), no current plan to fix or rewrite the DUP code, (2015 at the earliest)
During a DUP, the drives actually go idle, (not enough buffers to keep the drives streaming)
IBM said the DUP code would need hundreds, or maybe even thousands of buffers, to keep the drives streaming.
As LTO becomes bigger and faster, the problem gets exponentially worse, (we didn't notice this on our old 2 drive LTO3 library, but then we were not DUPPING everything either)
I'm not sure, but I think a LTO6 volume would take almost 20 hours to DUP.
LTO7 is around the corner, that will probably be around 40 hours to DUP.
IBM doesn't have or publish DUP times, only read(restore) / write (save) times.
We are a relatively small shop, how do others and larger shops deal with this DUP issue.
If everyone would request a DCR, it might get fixed quicker.
Or, are there other options?
Thank You
_____
Paul Steinmetz
IBM i Systems Administrator
Pencor Services, Inc.
462 Delaware Ave
Palmerton Pa 18071
610-826-9117 work
610-826-9188 fax
610-349-0913 cell
610-377-6012 home
psteinmetz@xxxxxxxxxx
http://www.pencor.com/
midrange.com
