Want to split a single IG to multiple IGs

this is similar to what we do with our Oracle RAC boxes, some devices are unique to each host and some devices are visible by all nodes in the cluster. So let's say we have 3 nodes in the cluster, we create 3 storage groups for each node, 3 initiator groups for each node and 3 masking views for each node. These individual groups will be used to present devices that are unique for each host. Next we create another storage group that will contain devices that are shared between the nodes, we create cascaded initiator group that consists of individual initiator groups and finally we create a masking view that ties it all together.

Initiator Groups:

ig_oracleracdev1

ig_oracleracdev2

ig_oracleracdev3

igc_oracleracdev1_2_3  (cascaded initiator group)

Storage Groups:

sg_oracleracdev1

sg_oracleracdev2

sg_oracleracdev3

sgc_oracleracdev1_2_3

Masking Views:

mv_oracleracdev1

mv_oracleracdev2

mv_oracleracdev3

mvc_oracleracdev1_2_3

in your situations i don't know how to break it up without scheduling downtime.

You have two options

1) Take a downtime and create IGs as mentioned by Dynamox (cascade them)

or

2) Present the LUN to all WWNs and disable it from the host side on which you dont want to see it..

Both options are painful..

Thanks dynamox and Saurabh.

I think it all about pre-planning the clone allocation.Every individual host should have individual IGs,SGs and Views created in starting itself eventhough not allocating individually.

I am not sure , but may be i can create empty child IGs for Host_01, Host_02 ,Host_03 and Host_04 , add to the main IG( xxxxxx01_02_03_04)  then move( remove from parent add to child ) one HBA at a time from xxxxxx01_02_03_04 to child IGs.

EMC should have added some commands to move HBA WWN from one IG to another ...

thanks

yes, move is disruptive (In backend it does unmasking and remasking of the devices) but you can try it in lab and let us know if you see different results.

regards,

Saurabh

you can remove WWN from one IG and add it another IG, you could also move devices from one SG to another SG but i have a feeling it will be disruptive on the host side. Try it on a test system and let us know

How about adding cluster devices to all  the individual Server Storage Groups( Server1_SG , Server2_SG , Server3_SG and Server4_SG )  instead of adding  to a combined group( Server_1_2_3_4_SG ) . Do we required to have SAME lun id for each devices in a cluster environment ?

thanks

i am not sure how many devices are presented to individual storage groups but you could end up with devices that are presented at different LUN IDs. For platforms like VMware it's not an issue anymore ( see this discussion https://community.emc.com/thread/130993) , i am not sure about other application like RAC. I always keep things simple and consistent, easier to troubleshoot in the middle of the night

Thanks Dynamox ,  Yes ..it is always good to keep the things simple... 

But i am not sure in some situation it is getting very difficult with Vmax allocation .

For eg: i have individual allocation groups for Server1( Server1_IG, Server1_SG,Server1_View)  and Server2 , ( Server2_IG, Server2_SG,Server2_View ) and another combined groups for cluster allocation( Server1_2_IG, Server1_2_SG,Server1_2_View ) .

Now i want to move some devices assigned to Server1 to Server1_2 . Is that will be a good way,  first adding the devices to be shared to Server1_2_SG( okay .. i have the same LUN id as in Server_1 )  and then remove the same devices from Server1_SG ..

What will be the effect of a server viewing one device through multiple Storage Groups with same LUN Id ( let us say, device AAA is in Server1_SG and Server1_2_SG  , with same LUN Id 0x50 )

i think its complicated ..

any thoughts ..

i have not tried it so i am not sure what would happen. If LUN id is the same, i imagine host will not notice a thing ..try it in on a test system first and let us know

TESTED:

We cannot add same devices both to Storage Group Server1_SG and Server1_2_SG . We need to remove the devices from Server1_SG and then add to Server1_2_SG.

you can have devices in multiple storage groups, how did you test and what errors did you get ?

Yes , you are right , we can have devices in multiple storage groups , 

But if you consider below as my existing setup, i am not able to add the device AAA also to Server1_2_SG without removing first from Server1_SG , because Server1_2_IG contains Server1_IG .

So in short,  we cannot add a device to mutiple SGs linked with Views having common Initiator groups.

What does initiator group have to do with storage group ...did you actually try this?

Sent from my Verizon Wireless 4GLTE Phone

Check if u have added the Lun Consistency enable in Initiator group.

If you have enable it … that might prevent luns /device sharing from 1 storage group to another since the LUN ID has to be unique.

@ dynamox -

Yes i tried this and got the following error.

"The operation cannot proceed because one or more device(s) is already masked within a view"

@Jackie -

Lun Consistency not enabled for the IGs.