Tom, I agree 100% with you, in many cases, using LVM (with stripes) and PAV, we improve 100% of I/O capacity for a I/O intensive workload (eg. Oracle Database).
One critical point in some cases, is that the LVM architecture is not fully supported by vendors (eg. Oracle RAC using LVM volumes in cluster filesystem based on ASM technology is not supported by RedHat, Oracle or SuSE). At this point, the best way is use only PAV technologies (HyperPAV, Dynamic PAV, Static PAV, etc..) with a large number of "alias" volumes and MDISK's on z/VM directory (to use a parallel access on these volumes). But, considering the I/O capacity and the facility to manage, I suggest the use of SCSI/FCP volumes, of course, if you want this option. Regards, Fernando 2012/10/10 Duerbusch, Tom <[email protected]> > Just speaking to LVM... > > Striping the data across multiple volumes (which in modern dasd is already > stripped in the Raid array), would give you the best performance. > Especially if you can strip across multiple DS8000 (or other dasd > subsystems). > > But you can also use LVM as a pool of DASD, with no striping involved. > > In case 1, if you need to expand the LVM pool, it is a hassle. It might > mean backing up, reformatting and reloading the data. In any case, it > involves a knowledgeable person and most likely, downtime. > > In case 2, if you need to expand the LVM pool, you can just add disks to it > on the fly (and even easier with VM). No downtime. I add dasd to my LVM > pool in minutes. > > The trade off is normally (well isn't it always), performance vs man power. > If you find you really don't need the "BEST" performance, then make the > job easier. > > But then, I you know the requirements of your application. > > Tom Duerbusch > THD Consulting > > On Tue, Oct 9, 2012 at 5:50 PM, Brad Hinson <[email protected]> wrote: > > > Hi folks, > > > > What are the best practices for HyperPAV and LVM striping? I assumed > that > > if you have HyperPAV enabled, you don't need to stripe the data. Is this > > true, or if not, what is the best practice for optimum performance? > > > > I have lots of mod-9 ECKD with HyperPAV enabled, so I want to use LVM. > So > > my two choices are standard LVM, or LVM striping. If I stripe across the > > disks I spread the I/O across the physical volumes, but my gut tells me I > > shouldn't have to do this, since HyperPAV is moving around aliases > > dynamically. For example, say I have 2 PVs and 4 HyperPAV aliases. If I > > send some heavy I/O through the Linux (device-mapper) block device, then > I > > would assume: > > > > - #1, for the case with LVM striping enabled, LVM will spread the I/O to > > both PVs, and HyperPAV will assign 2 aliases to each PV since I'm banging > > on them both. > > - #2, for the case without LVM striping, HyperPAV will assign 4 aliases > to > > the first PV since that's the only one in use. > > > > In either case, it seems I'm using all 4 aliases, so seems like I would > > get the same performance. Please correct me if I'm wrong. And if so, > > which of these configs is better? > > > > Lastly, is there a presentation or doc that talks about how to enable > > HyperPAV in Linux, or is bringing the HyperPAV aliases online enough to > > trigger the dasd driver to do the right thing? > > > > Thanks as always, > > -Brad > > > > -- > > Brad Hinson > > Solution Architect, Red Hat > > +1 (919) 360-0443 > > > > > > > > > > ---------------------------------------------------------------------- > > 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 more information on Linux on System z, visit > > http://wiki.linuxvm.org/ > > > > > > -- > > ---------------------------------------------------------------------- > 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 more information on Linux on System z, visit > http://wiki.linuxvm.org/ > ---------------------------------------------------------------------- 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 more information on Linux on System z, visit http://wiki.linuxvm.org/
