Although I have been working as a storage admin for many years, I have to admit that I'm a noob when it comes to cabling. I seriously need a help on cabling as I don't have much experience with cabling. We do have FAS 3140 and 7 * DS4243 attached to it and I have to be able to hot-add 7 additional DS4243.
I'm attaching a config advisor for your review. I truly appreciate the community's help in advance.
Unfortunately, current cabling does not meet cabling rules described in Universal SAS cabling guide. Recommended action is to fix current cabing first, but if there are no free SAS ports on each controllers, you need to shutdown filer then recabling it.
If you are to sort this out without fixing cabling, we have to understand how each ports in controller and shelves are cabled exactly. Please attach "sysconfig -a" and "environment status" of each controller.
You can add new disks into existing aggregates regardless of physical cabling as far as there are recognized by Data ONTAP.
Following to cabling guide, port of opposite side of stack must be different. But, for example, shelf 5 is cabled to b ports. I have never heard any issue except cabling alert ASUP by insufficient port selection so far. As wrote above, it works so far, but it may have potential issue. If you have odd issue in storage subsystem, you will be instructed to fixit first by tech support.
This appears to be your config 2b/3b 1 disk shelf 2d/3b 4 disk shelves 2a/3a 2 disk shelves
I believe the max shelves in a stack is 9. You can hot add the additional seven shelves, you can spread them out across the various connection or you can start in new stack on 2a/3c which appears to be unused. You need to make sure you don't saturate each loop and consider how you are going to layout the aggregate.
NetApp has some good manuals on cabling. Most time you purchase additional equipment installation from NetApp is included.