symaccess -consistent_lun

when you add sym devices to a device group it will make sure that they are mapped to the same address on the FA.

what does this option do? where exactly this helps/benefits?

Is there a way to keep the lun id consistent across the R1 vmax  and R2 vmax FA's ?

"-consistent_lun" mapped to the same address on the FA.within vmax , How can we achieve the same address across the SRDF , ? on DMX we could control this by using map file :map dev xx FA xx lin id 01 ; vmax have Auto Prov. - any idea to keep the same address across RDF ~

use -lun when you add devices to storage group.

can't think of anything else other than consistency when you run symdev show and look at device properties.

I understood that enabling consistent_lun option on initiator groups will make sure it takes the same LUN address across all FA ports in that port group.

Can you list out some benefits?

Thanks

Dino

When the lun numbers are the same it makes it very clear from a host view that you are looking at the same device.

For cascaded IG's, (when creating them for clustered hosts / ESC etc.) you will get the same Lun across each SG in the child IG's. Otherwise you can get different physical hosts seeing the same devices, but with different LUNID... confusing.

We added this option in specifically for VMware environments when autoprovisioning came out. A few ESX versions back ESX required the LUN IDs to be the same across all paths in order for multipathing to work correctly. This isnt the case any more but there are some situations like RDMs and vMotion where they still need to be the same across hosts so this option is helpful in that regard. So enabling it on VMware clusters is still a best practice and like the others said makes management easier.

no problem...

Are you guys referring to LUN ID we ll get it by the below command?

symcfg -sid xxx list -dir 8G -p 0 -addr -avail

or LUN ID we see inside a masking view for each device?

Thanks

Dinesh

It is the host LUN ID, not the FA channel address. Using the -consistent_lun option is for the benefit of the host address. Using -consistent_lun you can still see some volumes using different FA channel addresses (if the same channel address wasn't available) but the host LUN address will be consistent and that is the address that matters to the host.

This is using the Dynamic LUN Addressing feature for reference.

Thanks Aran... Got it...

I'm getting the following error while setting consistent lun on existing IG

symaccess -sid 1234 -name xxxxxxxxxxx_ig -type initiator set consistent_lun on

The operation will result in consistent lun violation

and unable to Set Consistent_lun... Please suggest how to overcome this.

have you searched ?

https://support.emc.com/search/?text=The%20operation%20will%20result%20in%20consistent%20lun%20violation