combine between two active stacks

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

Hey.

I have a FAS8200 system (2 nodes) with 2 quad SAS ports slots per node.

In the system i have 4 stacks of IOM6 shelfs, so all of my SAS ports are taken,

I want to install a new shelf to the system with an IOM12.

Can I join two stacks (every stack with 4 shelfs) with aggregates on them without breaking them to free 4 ports for the new shelf?

If so, what's the procedure to do it? Even with downtime.

Re: combine between two active stacks

CHRISMAKI — Tue, 05 Dec 2023 00:58:33 GMT

Joining stacks of shelves is indeed possible provided you don't exceed the stack limits. If the shelves are DS2246 or DS4246 you'll be fine, but the HDD limit per stack is 240 devices so if the shelf type is DS4486, you can only have 5 per stack. Also, remember that your FAS8200 has miniSAS-HD ports and the IOM6 shelves have QSFP ports, so you're going to need different cables to do the procedure below. Now, assuming you're good on shelf types and cables, on to the procedure:

Abbreviations used below:

Controller A or B -> CA, CB

IOM-A or IOM-B -> IA, IB

Shelf # -> S##

You should currently have the following existing connections:

CA:0a -> S01:IA:Square

S01:IA:Circle -> S02:IA:Square

...

S04:IA:Circle -> CB:0d (remove this)

CA:0c -> S11:IA:Square (remove this)

S11:IA:Circle -> S12:IA:Square

...

S14:iA:Circle -> CB:0b

Make New Connection: S04:IA:Circle -> S11:IA:Square (Requires QSFP/QSFP cable)

Before continuing, wait a bit for SAS paths to settle.

Existing connections:

CB:0a -> S01:IB:Square

S01:IB:Circle -> S02:IB:Square

...

S14:IB:Circle -> CA:0d (remove this)

CB:0c -> S11:IB:Square (remove this)

S11:IB:Circle -> S12:IB:Square

...

S14:IB:Circle -> CA:0b

Make New Connection: S14:IB:Circle ->S11:IB:Square (Requires QSFP/QSFP cable)

Before continuing, wait a bit for SAS paths to settle.

Now the following ports should be free:

CA:0c, CB:0d, CA:0d, CB:0c

On both controllers, move the connection currently in 0b to 0d to maintain best practices.

Now the following ports should be free:

CA:0b, CB:0b, CA:0c, CB:0c

Use these for your new shelf.

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combine between two active stacks

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