On 2/18/09 1:52 PM, "Stewart Thomas J" <stewartthom...@johndeere.com> wrote:
>> From my notes, feel free to correct any errors. > > EDEVICE can be used to emulate ECKD on FBA. We did some testing with this and > were able to format the disk for use as z/VM minidisks. The setup was pretty > easy and once defined were controlled mostly the same as regular ECKD disk. > Per one of our IBM calls - Performance issues, not recommended at all. Nobody > else doing it that way. Poppycock. It is slower, however there are certainly people doing it. I know of at least two sites that are all-FCP, no ECKD at all, and are perfectly happy. > EDEVICE - Is this not recommended in any configuration, even low I/O servers? > Is that the plan 'forever', or just until anything might change relating to > performance improvements with newer versions of z/VM. > No, stick with ECKD or Linux owned FCP. See my earlier comments. It is a manageable problem if you get good performance data. > "Absent from this study is an evaluation of Diagnose X'250' with emulated FBA > DASD." - that was another question IBM could never answer at the time we > consulted them, basically how that might speed up the overhead of using an > EDEV. Or even what versions of z/VM and Linux would support that. Not directly Linux experience, but OpenSolaris certainly makes extensive use of that capability and it seems acceptable at a pretty good load. I'm sure others will chime in with their opinions. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
