Does it really matter as much as it used to? The amount of cache on a dasd subsystem and overall i/o seems more relevant for paging spikes. Not that i am advocating a complete dismissal of all the normal considerations.. but since writes are done to cache.. isn't it the foremost attribute these days?
Rob Schramm On Jan 3, 2014 4:15 PM, "Ron Hawkins" <ronjhawk...@sbcglobal.net> wrote: > Art, > > Channels paths, ports, Front End Directors and ports are easy to map so > that locals can be allocated across every possible path. > > The missing part of most strategies is understanding the parallelism from > the cache to the disk and array group. There are many schema available for > RAID and wide striping, and path boundaries within the storage to take > advantage of (or tie you up). > > Spend some time with your vendor to understand exactly what you have and > how you can use it to maximize parallelism. For example on 2 chassis VSP > you have two separate set of disk paths behind each control frame, so male > sure you page datasets are spread across each chassis, either by way of the > HDP pool definition or the parity groups you use in basic volume mode. > > Sorry for the Hitachi parlance, but it stresses the fact that you have to > design for the hardware you are using. An EMC methodology will not be best > practice for a DS8800, and an ESS methodology will not work on an Hitachi. > > With the relative inactivity of page datasets, I would suggest one uniform > rule when tired storage is used would be to lock them into tier one > storage. You don't want the empty slots migrated down to SATA or external > storage when they suddenly get busy. > > Ron > > > -----Original Message----- > > From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] > > On Behalf Of Art Gutowski > > Sent: Friday, January 03, 2014 10:09 AM > > To: IBM-MAIN@LISTSERV.UA.EDU > > Subject: Re: [IBM-MAIN] Local Page dataset sizing/quantity ROT? > > > > Yes, how to maximize parallelism is the pertinent question. > > > > Let's assume for the sake of argument, DS88xx with no SSD. > > Mix of 3390-3, -9, and -27; HiperPAV enabled, with DASD defined as SHARED > > in the IODF, and some shared across Sysplex boundaries (understood this > is > > not utopian, but some customers do it, either self-managed or with the > > assistance of MIM/MII). > > > > How do you spread that 100GB across the farm, assuming you have at least > > 45 mod-3 equivalents? (If my math is not too far off, there's about > 2.2GB of > > usable page space on a mod-3). What would one avoid so as not to > handcuff > > HPAV? > > > > Regards, > > Art Gutowski > > General Motors Corporation > > > > On Thu, 2 Jan 2014 08:55:24 +0100, Vernooij, CP - SPLXM > > <kees.verno...@klm.com> wrote: > > >I agree, overall sizing is a minor issue: make sure there is enough, > what does > > 100GB more cost these days? > > >The more important issue is parallelism. Make sure ASM can do mass page > > outs if it needs to. Page in should not be >your problem I suppose. > > >This brings in the missing info: what is your storage device? > > >Why don't you have Hiperpav? > > >The DS88xx are much more flexible than the ESSs. > > > > Kees. > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to > > lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
