Arkturas wrote:
Please could someone clarify -
in a 7400 with 4 nodes (0,1,2,3) where 0,1 are paired and 2,3 are paired. Is it possible to lose one node from each pair without loss of connectivity to vv's.
Confirmed. I have a two T800s with 4 nodes each. When they perform major version upgrades, they reboot half the nodes at one time (odds or evens), then the other half to complete the upgrade non-disruptively. However, connectivity to the VVs is USER controlled and subject to user errors in zoning and exporting.
We do simple Host to VV without further specifying or locking down which nodes or ports so that the exports will find the hosts on any port, any node.
Zoning is important to plan and audit that its being done correctly. Health checks prior and during an Inserv upgrade will check for "Vertically connected" hosts and fail if found. Since the upgrades reboot 1/2 the nodes at once, it makes sure that there are no hosts connected to just the even nodes or just the odd nodes (odds/even are physically vertically stacked in S400/800 and T400/800). Easiest way to avoid this is ensure that each host WWN is zoned to both members of a node pair. I like this method as well because it splits the hosts load across 2 ports helping to mitigate any single noisy host from single handedly saturating a Inserv port. As in a case where you host is 4g ports, and your storage is also 4g ports... by zoning the host port to 2 nodes, if the host peaks its 4g port, that only results in 2g or 50% utilization on each of the 3par ports, so that adds a soft layer of performance protection. Assuming you also have 2 sans, an A side and a B side... zoning can get pretty hairy. In our case, we have 4 nodes, and each node has 4 ports for a total of 16 storage ports, we havs an A-side and a B-Side VSAN... I chose to put all the odd ports on the A-side, and all the even ports on the B-Side resulting in every NODE having 2 connections to each side of the SAN. So in my environment where I zone each dual attached host to 4 nodes, this nets out to 4 groups of 4 ports. When we add a new host, we pick the group with the least hosts attached and this keeps things pretty balanced and symmetrical.