topic Preferred Path in Command View 6 in MSA Storage

Preferred Path in Command View 6

City_Blue — Thu, 04 Oct 2007 03:15:25 GMT

i have been trying to find a full explination of the Prefferd path/mode optuions you can choose from in command view EVA v6

there are 4 options (5 if you count no prefrence)

path A - failover only
path A - faiover/failback
path B - failover only
path B - faiover/failback

i take it Failover only means if path A becomes unavalible it will fail over to Path B and not fail back when path A comes back.

but failover/failBack means once path A comes back it will fail back over to it's prefferd path.

Cheers

SD

Re: Preferred Path in Command View 6

Uwe Zessin — Thu, 04 Oct 2007 06:15:20 GMT

It should rather read 'controller' than 'path'. If a controller fails, management responsibility of its virtual disks is transferred to the surviving controller. 'failback' means that management is reverted if the failed controller comes back, although I have never tested that myself.

I see this has a 'hint' to establish a manual load distribution of virtual disks when the EVA starts. It is not always possible to manually transfer the ownership afterwards and a host can overrule this hint and request a failover on an active/passive array.

Current active/active EVAs can automatically transfer ownership if there is too much I/O going through the proxy controller.

It might still be necessary to choose a certain path preferrence for an specific operating system/ failover component (e.g. Linux QLogic failover driver).

Re: Preferred Path in Command View 6

City_Blue — Thu, 04 Oct 2007 06:17:24 GMT

cheers Uwe