In <bitnet.adsm-l%ADSM-L%95062211403398 AT VM.MARIST DOT EDU>, wts AT 
mail.caps.maine DOT edu (Wayne T. Smith) writes:
>> On Wed, 21 Jun 1995 at 17:05:05 GMT, Bill Colwell said:
>> > Caution - this ran pretty quickly at level 11 of the mvs server, but
>> > export was radically changed at level 12 and the performance of an
>> > export of a single node or filespace got much worse when actually
>> > moving the data.
>
>Melinda said..
>> I had thought that the rationale for the change to EXPORT in Level 12
>> was to improve performance.  (I can't tell, because every level higher
>> than 11 goes into a loop as soon as I try doing an EXPORT.)  Given that
>> my last EXPORT ran for 6.5 days under Level 11 (on a 3090E), I find your
>> statement disheartening to say the least.  Do you have any comparison
>> numbers?
>
>My level 14 VM server was able to PREVIEW=YES export a single client
>of 13K files and 358M data in 2 hours.  Doesn't look like I'll think
>about doing the same for the other million files we have backed up,
>although I have no idea if the process expands linearly.   :-(
>
>During the EXPORT NODE PREVIEW=YES FILEDATA=BACKUPActive, the server
>used 10-20% of my 3090-200J cpu, doing 5-10 I/Os per second.
>
>I recall someone mentioning EXPORT PREVIEW=YES was enhanced by
>eliminating an unnecessary sort ... if something else was done, it has
>yet to meet my expectations.
>
>Regards,
>
>Wayne T. Smith
>Systems Group -- CAPS        internet: wts AT maine.maine DOT edu
>University of Maine System   BITNET/CREN: WTS@MAINE

The PREVIEW=YES enhancement has been broken by the much larger export
enhancement starting at level 12.  (Apar pn55134 eliminated the sort
for preview=yes, back when sorts were done).  I used to be able to
do a 1 node preview=yes export in 2 minutes, and I have a wimpier cpu
than you!  It appears the export is now useful only
for disaster recovery and
it isn't really very good at that either!

Bill Colwell
C. S. Draper Lab
Email: BColwell AT draper DOT com
Voice: 617-258-1550