On 8 November 2012 18:03, Marcy Cortes <[email protected]> wrote: > Yes, Rob is right (as usual). Definitely PPRC is in play with the numbers I > reported. Probably XRC write pacing is involved too. > > I tried it on a non-PPRC'd, non-XRC'd device. I only had 10,000 cyl > available there. That took 3:30. If I assume linear and multiple by 6.55 > that would be 23 minutes. > Writing all zeros took 2:03 - so that would be about 13.5 minutes. FWIW the > PPRC is 11 miles and normally adds about 1 ms to i/o time.
My guess for 20 min was assuming 1 ms I/O response. Adding 1 ms for PRPC gives you 40 min. > So I do have a penalty there, but dasdfmt could be doing much better. > We'll wait to see what Peter O comes up with :) While you're at it, give ICKDSF a try on the non-PPRC volume. From looking at the trace, I would expect it take 1/10th of the SSCH's and thus have less of the round trip overhead. That's something dasdfmt could use as well. Rob ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
