are required. The IP addresses of the nodes in the cluster are utilized via the
Distributed Network Name (DNN) that is configured.
All of the nodes in the cluster are offering the same file service and therefore share
with the SoFS. There is a change in functionality between Windows Server 2012 and
Windows Server 2012 R2. In Windows Server 2012, a single SMB client connects to
only one of the nodes in the cluster simultaneously, even if establishing multiple
connections. When the SMB client initiates connections, it initially gets a list of all the
IP addresses for the hosts in the cluster and picks one of them for initiating the SMB
session. It then uses only that node, unless that node experiences a problem, in which
case it will converse with an alternate node. The exception is that the SMB client does
communicate with a second node when leveraging the witness service that I
previously discussed. Windows Server 2012 R2 introduced a rebalancing feature that
has two components:
The CSV disk ownerships are distributed evenly between all nodes in the cluster,
spreading the workload.
SMB connections are rebalanced so that clients are directed to the CSV owner,
giving the most optimal connection when used with clustered Storage Spaces.
(This rebalancing is not required when using symmetrical storage such as Fibre
Channel–connected SANs because every node has equivalent connectivity.)This means that a single SMB client could now be connected to multiple nodes in a
cluster via SMB instead of a single node.
SMB MULTICHANNEL
It is critical to avoid any single points of failure in any solution, and if SMB is being
used to access the storage containing virtual machines, there must be resiliency to
prevent a single network adapter, network cable, or network switch from failing. In
storage fabrics, technologies such as multipath I/O (MPIO) are used to provide
multiple paths to storage, and this same idea is now possible with SMB using SMB
Multichannel.
SMB Multichannel allows an SMB client to establish multiple connections for a single
session, providing protection from a single connection failure as well as adding
performance. As with most of the SMB 3 features, no manual steps are required to
utilize SMB Multichannel; it happens automatically. Once the initial SMB connection
has been established, the SMB client looks for additional paths to the SMB server, and
where multiple network connections are present, those additional paths are utilized.
This would be apparent if you’re monitoring a file-copy operation as initially only a
single connection’s worth of bandwidth. However, the bandwidth would double as the
second connection was established, and the bandwidth aggregated, then the third
connection, and so on. In the event that a connection fails, there are still other
connections to continue the SMB channel without interruption.
To see whether SMB Multichannel is being utilized from your server, use the Get-