My gut tells me that 2 queues to 2 devices is better then 4 queues to one device...
Seems like I saw something out there discussing this but can't find it - I will repost if I do. Scott Rohling On Tue, Oct 9, 2012 at 3:50 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/
