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8028 Views 6 Replies Latest reply: May 27, 2009 2:03 PM by William Lloyd
Currently Being ModeratedMar 4, 2009 8:14 PM (in response to Richard21)Multipathing should "just work" as of 10.5.2.
That said, the last time I tried connecting an Xserve to a NetApp over fibre there were issues -- mainly because the NetApp performance was not good (this was 6 shelves of 14 fiber drives). The NetApp insisted on doing "housekeeping" every 45 seconds or so and as such could not support uncompressed SD without dropping frames.8-Core Mac Pro, Mac OS X (10.5.5)
Currently Being ModeratedMar 10, 2009 5:00 AM (in response to William Lloyd)You are quite right, it does "just work", but it appears to work in a different way from most other implementations.
I have found through experimentation that when multiple paths are presented to the same disk array controller port, then OS X does indeed multipath the LUNs. But when multiple paths are presented that go through different controller ports, then the LUN appears once for each controller port. So if you have connected in 2 controller ports, the LUN appears twice, 3 controller ports, you get 3 LUNS etc. Therefore, it looks like OS X virtualises the target and not the LUN.
This is very irritating, to multipath correctly in OS X, this means that the disk array you buy has to support controller virtualisation. The NetApp ones do through the "Single Image" mode where all controllers appear as 1 device (a single WWN). It would be good if OS X virtualised the LUN like most other multipathing solutions.MacBook 4.1, Mac OS X (10.5.6)
Currently Being ModeratedMar 10, 2009 5:46 AM (in response to Richard21)Hello Richard,
your are right with your conclusion. Leopard is not using a LUN-Multipathing and therefore the same LUN appears twice if the second storage-controller has his own WWNN. You would need to run with the same WWNN or with a different HBA/driver.Mac OS X (10.5.6)
Currently Being ModeratedMar 24, 2009 6:17 PM (in response to urendels)Proper multi pathing is NOT possible with automatic fail over with the Promise Raids and OSX.
According to the Promise Web site
“ Please have in mind the following: we present unique WWNN (World Wide Node Name) per controller. We do LUN based as apposed to Target based implementation;”
From the Apple Dev web site
Mac OS X provides multipathing support on a per-target basis. Multipathing at the LUN level is not currently supported.
This dates back to 10.3.5 and has not changes since.
BRETTMac OS X (10.5.6)
Currently Being ModeratedMay 27, 2009 2:03 PM (in response to Ofer Arbeli)They should just appear. You don't have any zones set on a switch? Try rebooting the host.
Note: This is really a threadjack, as your question has little to no relation to the post at hand.8-Core Mac Pro, Mac OS X (10.5.7)