EMC Storage Product Knowledge Sharing

There is available WWN decoder tool for EMC but I am going to discuss how to decode manually?
Each Symmetrix SAF port, RAF port, EF ficon port or DAF port (DMX only) has a unique worldwide name (WWN). The WWN is associated with the Tachyon chip on the director. It was intended to remain unique per director so that the director can be accessed on a storage area network. The Symmetrix SAF/RAF/DAF/EF WWN is dependent on the Symmetrix serial number, the director number, the processor letter, and the port on the processor. When the SAF/RAF/DAF is inserted into the Symmetrix, it discovers the Symmetrix serial number and slot number and the WWNs are set for the ports on the director.

Symm 4/4.8/5 (2-port or 4-port) Fibre Channel front directors, the WWN breakdown are as follows:

For Symm DMX product family (DMX-1/2/3), the WWN breakdown are as follows:

The director WWN (5006048ACCC86A32) can be broken down (in binary) as follows:

There are different type of SAN like IP SAN, NAS over SAN etc... We will discuss about Fibre Channel SAN. It gives you more option in order to manage and minimize downtime means reducing company cost.

In general if you think storage environments, physical interfaces to storage consisted of parallel SCSI channels supporting a small number of SCSI devices. With Fibre Channel, the technology provides a means to implement robust storage area networks that may consist of 100’s of devices. Fibre Channel storage area networks yield a capability that supports high bandwidth storage traffic on the order of 100 MB/s, and enhancements to the Fibre Channel standard will support even higher bandwidth in the near future.

Depending on the implementation, several different components can be used to build a Fibre Channel storage area network. The Fibre Channel SAN consists of components such as storage subsystems, storage devices, and server systems that are attached to a Fibre Channel network using Fibre Channel adapters. Fibre Channel networks in turn may be composed of many different types of interconnect entities. Examples of interconnect entities are switches, hubs, and bridges.

There are various type of SAN implementation so lets discuss little bit about physical view and logical view of SAN.

The physical view allows the physical components of a SAN to be identified and the associated
physical topology between them to be understood. Similarly, the logical view allows the relationships and associations between SAN entities to be identified and understood.

Physical View

From a physical standpoint, a SAN environment typically consists of four major classes of components. These four classes are:
· End-user platforms such as desktops and/or thin clients;
· Server systems;
· Storage devices and storage subsystems;
· Interconnect entities.
Typically, network facilities based on traditional LAN and WAN technology provide connectivity between end-user platforms and server system components. However in some cases, end-user platforms may be attached to the Fibre Channel network and may access storage devices directly. Server system components in a SAN environment can exist independently or as a cluster. As processing requirements continue to increase, computing clusters are becoming more prevalent.

We are using new term cluster. this itself is big topic to cover but we will have brief idea about cluster. A cluster is defined as a group of independent computers managed as a single system for higher availability, easier manageability, and greater scalability. Server system components are
interconnected using specialized cluster interconnects or open clustering technologies such as the Fibre Channel - Virtual Interface mapping. Storage subsystems are connected to server systems, to end–user platforms, and to each other using the facilities of a Fibre Channel network. The Fibre Channel network is made up of various interconnect entities that may include switches, hubs, and bridges.

Logical View

From a logical perspective, a SAN environment consists of SAN components and resources, as well as their relationships, dependencies and other associations. Relationships, dependencies, and associations between SAN components are not necessarily constrained by physical connectivity. For example, a SAN relationship may be established between a client and a
group of storage devices that are not physically co-located. Logical relationships play a key role in the management of SAN environments. Some key relationships in the SAN environment are identified below:

· Storage subsystems and interconnect entities;
· Between storage subsystems;
· Server systems and storage subsystems (including adapters);
· Server systems and end-user components;
· Storage and end-user components;
· Between server systems.

As a specific example, one type of relationship is the concept of a logical entity group. In this case, server system components and storage components are logically classified as connected components because they are both attached to the Fibre Channel network. A logical entity group forms a private virtual network or zone within the SAN environment with a specific set of
connected entities as members. Communication within each zone is restricted to its members.
In another example, where a Fibre Channel network is implemented using a switched fabric, the Fibre Channel network may further still be broken down into logically independent sections called sub-fabrics for each possible combination of data rate and class of service. Sub-fabrics are again divided into regions and extended-regions based on compatible service parameters.
Regions and extended regions can also be divided into partitions called zones for administrative purposes.

You have two fabrics running off of two switches. You'd like to make them one fabric. How to do that? For the most part, it's simply connecting the two switches via e_ports.

Before doing that, however, realize there's several factors that can prevent them from mergingg

1. Incompatible operating parameters such as RA_TOV and ED_TOV
2. Duplicate domain IDs.
3. Incompatible zoning configurations
4. No principal switch (priority set to 255 on all switches)
5. No response from the switch (hello sent every 30 seconds)

To avoid the issues above:

1. Check IPs on all Service Processors and switches; deconflict as necessary.
2. Ensure that all switches have unique domain ids.
3. Ensure that operating parameters are the same.
4. Ensure there aren't any zoning conflicts in the fabric (port zones, etc).

Once that's done:

1. Physically link the switches
2. View the active zone set to ensure the merge happens.
3. Save the active zone set
4. Activate the new zone set.