>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.
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. IBM also mentioned multipathing only really true in Linux (when configured), not in EDEV. I also had a link to the following IBM report: http://www.vm.ibm.com/perf/reports/zvm/html/520lxd.html "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. Our research for this was back on z/VM 5.3, maybe 12-18 months ago. -----Original Message----- From: Linux on 390 Port [mailto:[email protected]] On Behalf Of Adam Thornton Sent: Wednesday, February 18, 2009 10:12 AM To: [email protected] Subject: Re: Size of Linux DASD under Z/VM? On Feb 18, 2009, at 10:02 AM, Stewart Thomas J wrote: > We had an IBM consultant come in and told us to never use EDEV for > Linux guests. That's fascinating. What were the reasons given? Adam ---------------------------------------------------------------------- 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 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
