More detail about fabric rebuild

[longbango]

Hi all, many thanks for reading my questions:

i have 3 san switches A, B, C; connected together as a fabric, only switch C has connected devices and the switch B is the principal one, so my questions are:

1. If i remove the switch A from the fabric (A is connected with B via E_port), will it trigger fabric rebuild event?

2. I already knew that if i set C as the principal switch by typing "fabricprincipal -p 1" and then remove B from the fabric, it will trigger a fabric rebuild event and after that, C will be the principal one, but is there a more detail log about this event? how can i get it?

3. During the fabric rebuild, are all of the data links between hosts and storage devices disrupted? And how long does it take?

4. Is there a technical documentation about fabric rebuild?

Thanks 

Long

[Martin.Sjölin · Accepted solution]

Hi Long,

Some details are covered in the following document

https://community.brocade.com/dtscp75322/attachments/dtscp75322/fibre/25322/1/Availability_LANs_SANs_GA-CB-138-00.pdf

During the 5-15 second of the BF (Build Fabric) the traffic is not interrupted if it does not pass via switch A.

Only traffic which is passing an ISL(s) or switch which is taken offline is impacted, no other traffic.

For the fabricprincipal, you could in fact move the principal by on switch C by forcing a build fabric before removing the switch

fabricprincipal -p 1 -f

which will not impact traffic at all (see attached article). Notice that then removing the switch A, you only have to deal

with the change in topology - no real traffic is going over the ISL between B and A, only switch related, I assume.

Further, I assume that iod is disable (iodset), and lossless is enabled - that is pending your switch hardware and FOS version.

To summarize:

1. yes, a BF will occur

2. look at the fabriclog CLI (fabriclog -s) on switch B and the new principal (switch C)

3. During a BF traffic is flowing (see referenced paper).  Only effect are on link taken down and potentially caused by iod setting

[longbango]

Thank you for answering my questions, that helped me a lot!

Regards

Long