HW cable configuration verification (single-path & multi-path on FAS2720)

SKHONG — Wed, 04 Jun 2025 09:43:19 GMT

Dear Sirs:

I have a single chassis of FAS2720 (two nodes with HA).

FAS2720 HW description
1. two nodes (two controllers) with HA.
2. No attached extension disk shelf.
3. no SAS-extension port (0a,0b) cable connected. For empty status on each 0a,0b SAS-ports.

When I check the sysconfig -a on admin mode, the output is shown as "Single-Path".
Of course, there is no cross-connection between controller_A and controller_B on base system chassis's SAS ports.

The SAS path redundancy is single-path.
if there is a disk shelf installed on this FAS2720, the SAS path redundancy should be Multi-Path.

I think that the backend of the chassis connection is connected with controller A/B.

Question 1. Is it normal or abnormal status?

Question 2. if there is controller failover/takeover operation, is there another issue with the loss of the disk path because of the single-path condition?

Someone told me the SAS cable should be connected between controller_A's ports and controller_B's ports under the cross-connection rule.

e.g. > Connect between controller_A's 0a and controller_B's 0b and connect between controller_A's 0b and controller_B's 0a.

Please let me know if you have any tips or formal documents.

Kind Regards!

SangKyun, Hong

Re: HW cable configuration verification (single-path & multi-path on FAS2720)

andris — Wed, 06 Dec 2023 17:01:17 GMT

A1. It is "normal" to not cross-connect the SAS ports when you do not have any external storage shelves.

See: https://kb.netapp.com/onprem/ontap/hardware/Are_SAS_cables_required_for_FAS_or_AFF_systems_with_internal_only_storage

A2: Though it is "single-path", that path is extremely reliable (since it is completely internal). If you do wish the most reliability, you can still cross-connect the SAS port - if desired.

That said, the newer FAS2820 does improve on the FAS2720 in this regard - there are two internal paths.

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HW cable configuration verification (single-path & multi-path on FAS2720)

Re: HW cable configuration verification (single-path & multi-path on FAS2720)