I view port as a part of the path. I may have been a little loose on my terms. I am describing paths that enter different ports on the device - not the paths through the same port that you describe. Could be 1 adapter to a switch with 2 switch connections to 2 ports on the target; or 2 adapters, each with an independent path to a different port on the device. Relative to a single port on the device - I agree with you. Simple reservations only allow one initiator access. With multiple ports on the device, each which may be on different and independent "bus", simple reservation isn't sufficient. (yes - I'm using "bus" loosely - it may be an independent Parallel SCSI bus, or a independent fabric/zone, etc). -- James > -----Original Message----- > From: Mike Anderson [mailto:andmike@xxxxxxxxxx] > Sent: Thursday, January 29, 2004 1:31 PM > To: Smart, James > Cc: 'James Bottomley'; Philip R. Auld; 'Patrick Mansfield'; Simon > Kelley; SCSI Mailing List; dm-devel@xxxxxxxxxxx > Subject: Re: Is there a grand plan for FC failover? > > > Smart, James [James.Smart@xxxxxxxxxx] wrote: > > > > > > > -----Original Message----- > > > From: James Bottomley [mailto:James.Bottomley@xxxxxxxxxxxx] > > > > > > On Thu, 2004-01-29 at 09:49, Philip R. Auld wrote: > > > > It needs to be known to the pathing layer if you've got > > > load balancing. > > > > It has to know which path has the reservation and only > use that one. > > > > > > Well, yes, but your multiple active path implementation > just collapsed > > > back down to single path in the face of reservations, so it would > > > probably be better simply to use failover in the face of > reservations > > > and clustering. > > > > Why do you imply that you're down to a single path ? With > multiple port > > devices, and the T10 unclarity on multiport support, simple > reservations > > didn't bring you down to the single port access you are > describing. Some > > devices may have implemented it this way, but the standard > didn't say they > > had to or even that they should. > > > > And this picture changes significantly with the use of Persistent > > Reservations and the use of keys. > > > > It appears you are mixing port and path. If you have multiple > paths to a > port created by multiple adapters connecting to this port > through a bus, > fabric, etc. then simple reservations should restrict you to only one > path to this port. Is there a device that implements simple > reservations > and allows multiple initiators access? > > -andmike > -- > Michael Anderson > andmike@xxxxxxxxxx >