If I could, I would stay with the 16 3390-3's. My reason is that the IO load is spread over more volumes. Also, if I could, I would spread the volumes over multiple CUs. That's how I look at.
Paul Feller AIT Mainframe Technical Support -----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of O'Brien, Dennis L Sent: Friday, October 03, 2008 11:11 AM To: IBMVM@LISTSERV.UARK.EDU Subject: Paging volumes, size vs. number We are sizing a new z/VM system for a Linux guest workload. We traditionally use 3390-3 size devices for paging. We determined that we need 16 3390-3's for this particular workload. Our DASD people asked if we could use 3390-9's instead. Based on space, they want to give us 6 3390-9's for paging (rounding up). Assuming we have four FICON channels, is there any performance benefit to having more than 4 paging devices? I.e. is 16 devices better than 6 on 4 channels? The system isn't built yet, so using a performance monitor isn't possible. Dennis O'Brien We are Borg of America. You will be assimilated. Resistance is futile.
