topic MCC distance between fabrics in ONTAP Discussions

MCC distance between fabrics

Leiz23 — Wed, 04 Jun 2025 09:54:11 GMT

Hi,

IHAC have multiple MCC-FC installed, now they are planning to move to MCC-IP.

They are using multiple providers for the DWDM and has possibility to face situation described in the MCC document below.

What is the reason behind this requirement? And what will happen when the distance between fabric1 and fabric2 is more than 20KM?

Thanks

Lei

Re: MCC distance between fabrics

AlexDawson — Mon, 09 Jan 2023 04:00:04 GMT

At a high level, distance = latency, which metrocluster is very sensitive to and this could cause RAID panics during disk scrubs.

That said, from my reading it seems the 20KM difference is a very conservative length limit added due to internal burt 1359947, and it is included to ensure we had a benchmark, and at a limit that you definitely won't have any problems with. Longer lengths may very well work, but you should work with your account team at NetApp to lodge an FPVR for them for the difference in length to be supported.

Hope this helps!

Re: MCC distance between fabrics

Leiz23 — Mon, 09 Jan 2023 06:24:24 GMT

Thank you, Alex.

Does that mean once burt 1359947 is fixed, this limitation will be removed? And same for the RAID panics during disk scrubs issue?

I guess there is a range instead of fixed distance. If 20km is the safest number, any idea what is the largest distance difference that we can support?

Re: MCC distance between fabrics

AlexDawson — Mon, 09 Jan 2023 08:17:56 GMT

No - the BURT ID is provided for the FPVR as it includes internal notes on the decision making process regarding the 20KM differential limit in the documentation. There is no defect to be fixed to make the limit go away.

Maximum distance for MCC-IP is 700KM

Re: MCC distance between fabrics

Leiz23 — Thu, 12 Jan 2023 03:54:05 GMT

Thank you, Alex.

I will work with account for further actions including FPVR.

Cheers

Lei