We're about to upgrade Brocade IBM FLEX FC5022 switch (should be equal to brocade 6547) from version 7.0.0_pha3.
Our destination version is 7.4x
1. Assuming we'll upgrade to 7.1, then 7.2, then 7,3 then 7.4 should the warm upgrade caues to any loss of paths / some kind of disruptions during the upgrade ?
2. Assuming going directly from 7.0. to 7.2 and from 7.2 to 7.4 - should it be disruptive by design?
yes, the FC5022 is equal 6547
It is not recommended to jump beetwen TWO release by Upgrade.
since you are on 7.0.0_pha3, I believe if I remember correct, you need a Intermediate FOS 7.x release before you can proceed with other upgrade.
I would suggest to open a TAC with IBM.
from Release Notes 7.2.0a
--->>>Support merged to FOS v7.2: 5431, 6547, M6505
in order to upgrade from current 7.0.0_pha non-disruptive to 7.2.x you need first to upgrade tpo any intermediate release.
for this reason, you would suggest to open a TAC with the vendor in such case IBM.