one to many, IGs or SGs

You should consider this below restrictions before planning to use cascaded SG's. In case your backup host dont have exisitng luns and your intending to make all ESX cluster luns visible to this backup boxes then create cascaded IG and add them to ESX cluster IG but if you have luns on backup host and which cant be shared with ESX and vice versa some luns on ESX cant be share on backup then cascaded IG will also wont work untill you isolate one HBA and create IG of it and do some planning.

The following restrictions exist for child SGs belonging to a single parent SG:
◆ Only a single level of cascading is permitted. A parent SG may not be a child of another
SG.
◆ SGs can only contain devices or other SGs. No mixing is permitted. This covers
attempts to perform device add operations to a parent SG. This also covers attempts
to add child SGs to an SG containing devices.
◆ A parent can have up to 32 child SGs.
◆ A parent SG cannot inherit the same device from more than one child SG.
◆ A child SG may only be contained by a single parent SG.
◆ An SG associated with a FAST policy is not allowed to be a parent SG.
In addition, the following existing restrictions affect add operations:
◆ When in a view the total number of devices inherited by a parent SG cannot exceed
4096 devices.

If you want to use cascaded SG then better is make a child SG for the luns which need to be shared across both ESX cluster and backup and one SG which is for luns not to be shared and add them to a parent SG in ESX cluster and seperatly make a view with child SG and backup host IG also which needs to be shared. We started using this quater some of cascaded SG's but it needed some planning to rearrange some existing SG's.

Regards,

Mrinal Dani