> Switching LUNs from one path to another is not a fast process and if > this happens during periods of heaving IO periods, significant thrashing > can result. > > I think if we want to play at the Enterprise level where there are many > servers connected up to large arrays I don't think it is a good idea to > knowingly cause disruptions to others on the SAN. Causing LUNs to > switch from one path to another is such a behavior. > I certainly don't militate for the NOSTARTONADD flag removal for all devices. I just consider it annoying for the HSG80 / HSV* family controlers : - Either they are in failover mode and there is no bouncing possible, so start_stop is harmless - Either they are in multibus mode, then not sending start_stop before READ CAPA lead to cmd failure and wrong size stored. Hence ghosts path are ununsable even when they come up. [Here, I shamely hide the device-mapper hooks on path activation could work] - Either way, these controler families are *not* high-end devices, whatever the criteria (capacity, throughput, cache, alarming, ...). The whole ghost-path notion being the best evidence. regards, -- christophe varoqui <christophe.varoqui@xxxxxxx>
