topic Half of Drives in a Shelf Use One Slot/Port, The Other Half Uses Another in ONTAP Discussions

Half of Drives in a Shelf Use One Slot/Port, The Other Half Uses Another

TMADOCTHOMAS — Wed, 04 Jun 2025 18:08:23 GMT

I am making plans to remove three unused shelves from a 7-mode system. The three shelves form a complete stack so it's pretty straightforward, however I noticed that one of the three shelves contain about half of it's disks with one slot/port and the other half with a different slot/port. I don't know if this is common or not. The other two shelves show the same slot/port on each disk.

Any thoughts/ideas? Is this a concern?

Examples:

Some disks on shelf 21 look like this: 3d.21.0, 3d.21.2, 3d.21.4

The others look like this: 5a.21.1, 5a.21.3, 5a.21.5

Re: Half of Drives in a Shelf Use One Slot/Port, The Other Half Uses Another

aborzenkov — Thu, 01 Dec 2016 07:00:14 GMT

You shelf has dual-path connection and Data ONTAP tries to balance access across two connected HBAs. So it is normal, nothing to be concerned about.

Re: Half of Drives in a Shelf Use One Slot/Port, The Other Half Uses Another

TMADOCTHOMAS — Thu, 01 Dec 2016 14:05:56 GMT

Thank you aborzenkov, that is helpful. Why would some shelves show the same slot/port for every disk in the shelf, and others like the one I'm referencing in this post?

For example, another shelf in the same stack, shelf 22, shows every disk with a similar address:

5a.22.0, 5a.22.1, 5a.22.2, 5a.22.3, etc.

Why are trays 20 and 22 like this, while tray 21 switches between 5a and 3d?