LUN ID

[saranraj456]

Hi All,

Does LUN id in netapp filer is used for any reference purpose ?.if so,how it would refer.

Is it been going to have any influence on host end?

Cheers,

Saran

[jacint]

Hi,

the host identifies the LUN by the LUN ID:

"A LUN must have a unique identification number (ID) so that the host can identify and access the

LUN."

cheers,

Jacint

[arunchak]

Yea, Lun id is always used to differentiate the LUNs uniquely.

Hey we can also use the info in this file "/proc/scsi/scsi" to find whether the LUN is from NetApp or whether it is from other vendors with their specific LUN id's (as we were discussing in the post http://communities.netapp.com/message/61532#61532):

[root@warspite ~]# cat /proc/scsi/scsi

Attached devices:

Host: scsi0 Channel: 00 Id: 00 Lun: 00

  Vendor: IBM-ESXS Model: CBR036C31210ESFN Rev: DFQG

  Type:   Direct-Access                    ANSI SCSI revision: 04

Host: scsi0 Channel: 00 Id: 01 Lun: 00

  Vendor: IBM-ESXS Model: ST336607LC    FN Rev: B25H

  Type:   Direct-Access                    ANSI SCSI revision: 03

Host: scsi0 Channel: 00 Id: 08 Lun: 00

  Vendor: IBM      Model: 25P3495a S320  1 Rev: 1

  Type:   Processor                        ANSI SCSI revision: 02

Host: scsi3 Channel: 00 Id: 00 Lun: 00

  Vendor: NETAPP   Model: LUN              Rev: 7330

  Type:   Direct-Access                    ANSI SCSI revision: 04

Host: scsi3 Channel: 00 Id: 00 Lun: 01

  Vendor: NETAPP   Model: LUN              Rev: 7330

  Type:   Direct-Access                    ANSI SCSI revision: 04

Host: scsi3 Channel: 00 Id: 00 Lun: 03

  Vendor: NETAPP   Model: LUN              Rev: 7330

  Type:   Direct-Access                    ANSI SCSI revision: 04

Thanks,

  Arun

[saranraj456]

Do we need to have the same LUN ID across ,when we are using LUNs to cluster servers?

[jacint]

hi,

when you provision a LUN for a Cluster, usually you create an igroup which contains the FC or iSCSI address of the HBAs from all the Cluster nodes. When you provision the LUN and select the appropriate igroup, you'll select the LUN ID, which will be the same for all cluster nodes in this way.

[saranraj456]

here i had a seperate igroup for each node in cluster

[jacint]

I'd recommend to use a single igroup. Here's what SAN Administration Guide says:

"Typically, you want all of the host’s HBAs or software initiators to have access to a LUN. If you are using multipathing software or have clustered hosts,

each HBA or software initiator of each clustered host needs redundant paths to the same LUN. "

[saranraj456]

the recommendations are, invidual igroup in my case to map a new LUN should i have to maintain same LUN ID ?

[arunchak]

Hi,

LUN id is used to identify the LUN uniquely in the mapped Host. What exactly are you trying to achieve here? If you are mapping two LUNs to the same host then do not have same LUN id.

[saranraj456]

Arun,

We have a 2 node cluster (active /passive) server with two igroups separately ,in regards to LUN id do we need to do have the same  ID for both igroups.If it is not be the same what would be  impact.

Saran