I could test "OEL6 with RHEL kernel + Powerpath" vs "OEL6 with UEK2 kernel + dm-mpio", but anyway this would not give the answer whether Powerpath is faster or slower than dm-mpio by itself, since the kernels would be different.I wonder how the answer whether EMC Powerpath or DM Multipath is faster can help you? Apparently you cannot use Powerpath with the UEK2 kernel and have a certified system at the same time, at least not at this time. However there is no reason to throw the towel yet. If the use of Powerpath instead of Multipath is so critical, why not using Oracle Linux 5.7, which is certified? If you check the EMC compatibility matrix (esm_by_os), it actually shows some systems including Clariion supported for Oracle Linux 6.2 with UEK kernel. You might want to take a closer look.
mdaskalov wrote:This may be natural, but it's completely wrong: there is no similarity between the native multipathing on Windows and that on Linux, as they don't even share a common code base. So this assumption is invalid.
It is kind of natural to have a feeling that "native multipathing" is similar on operating systems. So there are some "indications" that dm-mpio might be slower than powerpath, if powerpath was available on the specific operating system.