# Networking Configurations

The Unified Storage Device (USD), originally called a "filer", has been since its conception a decade ago an appliance designed to be attached to the world through a network. It does most of its work over just three networked fabrics:

Ethernet, 10/100BT, GbE and 10 GbE

Fibre Channel, both out the "back end", which is where the disks and shelves are attached (optionally through a Brocade switch) and out the "front end" through FCP for use in SAN-style configurations.

SAS, from the back end only at present (2007).

There are additional connections needed for power, and for connecting two devices together into a cluster, but the simplicity of the network-attached approach has been a major selling point of USDs from the beginning.

In spite of this simplicity, network configuration issues are one of the most common sources of phone calls to technical support. Some of the most common queries are as follows:

Duplex settings. You can't get this wrong on gigabit Ethernet (it's always full-duplex). On 10/100BT, however, it frequently happens that autonegotiated settings do the wrong thing, and you end up with a full-duplex device on one end and a half-duplex device on the other. This results in truly horrible performance, about five or 10 percent of a properly configured USD. Experienced administrators usually force both ends to full duplex instead of relying on auto-negotiation.

Improper netmasks. The USD needs to do broadcasts for some operations, so the servers it needs to talk to (DHCP for example) need to be within range of the broadcast allowed by the netmask.

Old machines used as domain controllers and other servers. Because of its high performance, the USD makes significantly greater demands on these servers than you might be used to.

Poor communication paths between USDs and Domain Controllers (DC) or Active Directory (AD) servers. These should be as clean as possible. It is a good idea to have an AD server or DC as 'close' to the USD as possible to assist in speedy authentication. Poor USD/DC communications often cause poor performance and/or authentication problems for users.

The USD and Primary Domain Controller (PDC) must be on the same subnet for initial CIFS setup in an NT4 domain.

USDs that are used as a database data store should be connected 'back to back' with the database server. Failure to do so can leave the database's communications with the data store subject to network issues.

A good clean and fast network setup is necessary to effectively utilize network-attached storage of any kind. Make every effort to have a fast and well-equipped network in place to effectively use the performance the USD is capable of and to maximize the productivity of your end users. This dictum is well understood in the Fibre Channel community; it is true no matter what kind of storage network one is dealing with.

Installing a USD for the first time might bring problems to the surface that were not evident before because of its high performance. The administrator-level netdiag command is very useful for flushing out these kind of dormant misconfiguration issues.

Related Topics

- Hardware

- WAFL, Snapshot copies, and derivative software

- WAFL Storage Hierarchy

- RAID 4 and RAID 6

- Networking and Clustering

- MultiStore

- File Sharing

- Protocols

- Unified Storage

- Multiprotocol File Permissions

- Storage Resources Management

- Developing applications that talk to Unified Storage Devices