On Thursday, 11/08/2012 at 06:47 EST, Rob van der Heij <[email protected]> wrote: > On a real round brown disk, doing a "format write" is a delicate > process that requires dedication and a steady hand. It's done one > track at a time. This takes a full round trip per track, so roughly 1 > million of those in your case. Given that, 20 would be explained. > > If there's more FICON things in between, there may be more hops to > take and your I/O response might be worse. The amount of data does not > look like it would saturate your NVS, but who knows what else is going > on. If you upload an hour of data while this was running, I'd be most > happy to investigate what is going on and whether there is room for > improvement.
DS8000s return Device End as soon as the data is in NVS (non-volatile storage). Data is written to disk asynchronously, so the physical organization of a track is transparent to the I/O operation. Managing the cache to avoid I/O delays due to NVS destaging operations is one of the things a smart controller has to handle.) I will make the rash assumption that all modern storage controllers with NVS cache operate the same way. Alan Altmark Senior Managing z/VM and Linux Consultant IBM System Lab Services and Training ibm.com/systems/services/labservices office: 607.429.3323 mobile; 607.321.7556 [email protected] IBM Endicott ---------------------------------------------------------------------- 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/
