OK I compared ICKDSF to dasdfmt for Rob. And the other tests I happened to have run from the CPU at the site that didn't have the primary dasd. I was essentially adding another 11miles. Oops - not what I was intending to look at!
dasdfmt of 10000 cyl - non PPRC non XRC - 1:55 ICKDSF of 10000 cyl - non PPRC non XRC - 1:13 dasdfmt of 10000 cyl - PPRC, XRC'd - 5:00 ICKDSF of 10000 cyl - PPRC, XRC'd - 1:29 dasdfmt takes 57% more time thank ICKDSF on non-replicated disk and 237% more time on replicated disk if I did my math right. It looks like dasdfmt suffers way more at the hands of replication. Definitely room for improvement in it. Marcy This message may contain confidential and/or privileged information. If you are not the addressee or authorized to receive this for the addressee, you must not use, copy, disclose, or take any action based on this message or any information herein. If you have received this message in error, please advise the sender immediately by reply e-mail and delete this message. Thank you for your cooperation. -----Original Message----- From: Linux on 390 Port [mailto:[email protected]] On Behalf Of Rob van der Heij Sent: Thursday, November 08, 2012 9:22 AM To: [email protected] Subject: Re: [LINUX-390] dasdfmt - why are you so darn slow? 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/ ---------------------------------------------------------------------- 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/
