http://now.netapp.com/NOW/knowledge/docs/ontap/rel72/html/ontap/bsag/8cl us-f4.htm
-----Original Message----- From: Mike Ball [mailto:MBall@datalink.com] Sent: Tuesday, April 17, 2007 7:56 AM To: toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
Thanks for the responses but I am still confused about how the paths are determined. For example, lets say I have a FAS6030C (Node1 and Node2) running Data Ontap 7.2.1 with each head having 2 target ports each in a switched fibre fabric. In this fabric, I have a Windows host (running Snapdrive 4.2.1 and DSM 3.0) with a dual port fibre card. I create lun0 on Node1 from the Windows host via Snapdrive. How is the path chosen by the FAS6030C? Is there a round robin algorithm which gives out the target port on Node1 to the Windows host?
-----Original Message----- From: Paul Rosham [mailto:paulrosham@yahoo.com.au] Sent: Monday, April 16, 2007 11:26 PM To: 'Jack Lyons'; 'Nils Vogels' Cc: Mike Ball; toasters@mathworks.com Subject: RE: Information on how Netapp single_image mode works
In addition, anything with a reasonable NVRAM/Cluster interconnect setup (i.e. 3000, 6000 series) the additional latency of the request passing to the correct head via the cluster interconect is almost negligible.
-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Jack Lyons Sent: Tuesday, 17 April 2007 11:10 AM To: Nils Vogels Cc: Mike Ball; toasters@mathworks.com Subject: Re: Information on how Netapp single_image mode works
one caveat, based on my experience
the host based software will see all paths to the filer as equal, so if you hit the WWPN on the "other" head of the cluster, you will get an error message and an ASUP. It is annoying, and as far as I know, not a problem.
Jack
Nils Vogels wrote:
Hey Mike,
On 4/16/07, Mike Ball MBall@datalink.com wrote:
I am trying to find additional information on how Netapp single_image
mode works in a clustered environment as it pertains to pathing. Single_image mode pulls all the WWPN's from the Netapp cluster and presents it to the SAN as one WWNN. What I would like to know is how paths are determined from hosts to cluster nodes if no target portals
are defined?
There will be multiple paths available (at least 2, one for ClusterA, one for ClusterB) and you generally will need host-based path selection software to select the active one.
Some software selects on 'Most Recently Used', other selects on fixed path, this may vary per multipathing-software.