On 8 November 2012 20:54, Marcy Cortes <[email protected]> wrote:
> 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. I would have expected ICKDSF to have more advantage, but maybe the cost of reading back the cylinder is pretty heavy. I wish I had suggested the NOREADCHK option. > It looks like dasdfmt suffers way more at the hands of replication. > > Definitely room for improvement in it. It may be that the microcode in the disk subsystem recognizes the channel program and does smart things instead of replicating 64K per track to the other side. But the differences between the channel programs are just too big to just guess at where the trick is... For the time being, you could format it with ICKDSF and then DDR cylinder 1 from a Linux pack to fool dasdfmt... 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/
