Linux on 390 Port <[email protected]> wrote on 06/30/2009 11:19:34 AM:
> Mark Post wrote: > >>>> On 6/26/2009 at 8:31 AM, "Burton, Randy" <[email protected]> > >>>> wrote: > [snip....] > > > > I'm actually seeing some customers that _only_ have SCSI over FCP > > systems. They're relatively new mainframe shops, and so don't have a > > huge investment in ECKD emulation and FICON. From my perspective, > > that makes things a little bit more tricky than otherwise, but not > > prohibitively so. > > > I'm seeing that as well, sites new to the mainframe using only SCSI/FCP > attached disk storage. While it's not that much more difficult to use, > having SCSI/FCP disk means that the disk storage can not be managed by > tools like DIRMAINT. > > > The amount of performance-related data that is available for SCSI > > over FCP is improving over time, but from what I understand, it still > > lags behind FICON devices. So, when it's working well, you get > > better performance, but when it's not working well, it's harder to > > figure out why. So, like most things in IT and life, it's a tradeoff > > at least for now. > > > This is true....there is no performance data coming back from the > SCSI/FCP disk drives, as that functionality is simply not architectured > into the design of those systems. Who was it that said" If you can't > measure it, I'm just not interested...."? ;-) There is certainly is architected performance data for SCSI. Check out log select, log sense, 7.2.14 Statistics and Performance log pages, 7.2.15 Cache Memory Statistics log page, etc in SPC-4. sg_logs should retrieve this data, but I'm not sure if the all of the scsi tools work on linux on z. Ray Higgs System z FCP Development Bld. 706, B24 2455 South Road Poughkeepsie, NY 12601 (845) 435-8666, T/L 295-8666 [email protected] ---------------------------------------------------------------------- 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
