Swapping to vdisk on z/vm 5.1 is to your advantage, more so even than what you have heard for z/vm 5.2. on z/vm 5.1, there are below the 2gb storage line constraints. So I/O to a linux swap volume then contends for important storage. vdisk is page I/O, and not impacted by below the line constraint. so any installation with 2gb constraints on z/vm 5.1 will notice additional benefit by using vdisk instead of real disk. especailly if storage constrained. On z/vm 5.2, there is not this added constraint, so the benefit can be slightly less noticable. but still very significant. We've yet to see any valid measurements proving swap to real disk has ever been better than swap to vdisk. Maybe as soon as folks start to measure, the benefit they thought they were seeing with swap to real disk goes away????
Bennie Hicks wrote:
All, looking for comments (situation below) on VDISK implementation for linux swap. After having read all the recent posts on use of VDISK (including layers) which we intend to do, mainly interested in timing of same? 1. "proceed vs. wait" with implementing VDISK swap space for RHEL guests running on z/VM Version 5 Release 1.0, Service Level 0601 (64-bit). We have had zVM5.2 on standby awaiting a DASD subsystem replacement (now zVM5.3 is available :-) ) & no space for 2nd level installation/testing. Current LPAR's (on redundant z9's) are not currently storage constrained - 1st at 40% of 12G & 2nd at 60% of 8G (each defined less 1G as XSTORE). Note: aware of many Conference Presentations indicating much better memory management (ie. above 2G line) with 5.2 or above; hence wanting advise/opinions on proceeding at 5.1 vs. waiting. We had hoped to have the DASD subsystem upgraded in Jan, but still waiting - and best guess would be late April early May before VM upgrade could be done, so wondering if I would have any negative affects of proceeding with VDISK swap areas at 5.1? Opinions please! Thanks -- [EMAIL PROTECTED] ITS/CS Network Systems Programmer State of North Carolina Office of Information Technology Services
---------------------------------------------------------------------- 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
begin:vcard note:If you can't measure it, I'm just not interested version:2.1 end:vcard
