On Fri 17 May at 09:05:47 -0700 [EMAIL PROTECTED] said: >> So ... I'd -LOVE- to see multipath support on s390 that would give me the >> comfort of knowing I won't ever see multiple instances on the same physical >> disk being reported and also ... the added benefit of improved performance
>Is this any different than what happens in pretty much any OS or any of the >other linux architectures? If you have a Shark or whatever and have multiple scsi >or FC paths to its disks you get multiple sd's or hdisks or whatever that all >correspond to the same physical disk. >Patrick Mansfield just posted to the linux-scsi list the other day a patch >that pushes multipathing into the scsi mid-layer. That would allow you to >hide the multiple instances. Hi Tim, >From what I understand ... there are both differences as well as similarities. Scsi multipath support (1) only handles scsi drives (2) usually is limited to newer drives with burnt in drive ids (3) is supported in the generic scsi code i think and so scsi mp disk recognition in kept beneath the gendisk layer. 390 multipath support (1) handles any channel attached storage device (2) identifies drives by ch-cu-dev addressing (3) if supported in the io subsystem layer then the OS can't see and won't add multiple instances of the device to the gendisk list. >From recent posts ... sounds like I should be asking questions about PAV devices rather than multipath. -Don
