>I tried Mark Post's recommendation that I CMS format the volume but skip >the CMS reserve, and that did in fact allow me to install a new instance. >As a matter of fact, I have tried this a few times to make sure that the >first time was not a fluke, and apparently the CMS reserve step needs to be >skipped if installing to PAV enabled DASD. >If there are detailed instructions for actually making use of PAV with LVM >in SLES8, I would still be interested in seeing those. >I can even offer my services as a guinea pig if someone needs to test with >our specific hardware/software combination.
I thought I understood how PAV works and it was my impression that the i/o subsystem knew the addresses belonged to a PAV and would/could drive simultaneous i/o to the phys device. If so ... then the dasd driver would register a single disk with the block layer. Which means that lvm1 would not know about the multiple PAV addresses used by the i/o subsys ... only seeing a single disk. However, coming in through scsi, with multiple interfaces out to the storage, you would indeed see multiple disks registered with the block layer ... all of them mapped to the same phys disk. This is a situation in which I think you'd use lvm1 with its support for multi-paths. MD has also introduced multi-path support by adding an mp personality. Its job is to aggregate the multi-path disks and present them as a single md volume. This is real interesting stuff and I hope others can comment on it. -Don
