Getting started with terms

Cluster

A cluster is a pair of NetApp gFiler heads (or nodes) that are connected through an interconnect adapter and cables and are configured so that both gFiler heads share access to a set of Fibre Channel disks, subnets, and tape drives to provide fault tolerance. In most cases, the clustered nodes are two physically separate nodes. However, with the GF270c, a cluster consists of two internal gFiler heads that reside in the same appliance.

When one gFiler in a cluster undergoes a system failure and cannot reboot, the partner gFiler in the cluster can take over the failed gFiler functions and serve data. This process is known as a takeover.

In addition to enabling automatic takeover, you can also force a takeover at any time. You can cause a clustered gFiler to immediately halt and be taken over by its partner, allowing scheduled maintenance to be performed on the gFiler. Alternatively, you can cause a gFiler to halt while preventing its partner from taking over.

LUN

This guide uses the term LUN (Logical Unit Number) to describe an area on the storage subsystem that is available for a gFiler or non-gFiler host to read data from or write data to. You might be accustomed to hearing a different term to describe this area; the term varies among vendors and sometimes among platforms for the same vendor. See the Gateway Series Getting Started Guide for your storage subsystem for the specific term used for your platforms.

RAID protocols supported

gFilers support storage subsystems that use the RAID-1, RAID-5, and RAID-10 protocols, although the gFilers do not themselves use RAID-1, RAID-5, or RAID-10. The following illustration provides a conceptual view of RAID-0 used on the gFiler and the RAID-1, RAID-5, and RAID-10 storage subsystems.

The gFiler stripes across LUNs in RAID-0, thereby maximizing performance because it is using more spindles. Another benefit of the gFiler using RAID-0 for striping across LUNs is that you can add LUNs to a NetApp volume.

There is no need for the gFiler to provide disk protection. The LUNs are already protected with the redundancy provided by RAID-1, RAID-5, and RAID-10 on the storage systems.

Note
The filer uses the RAID-4 protocol for disk protection. RAID-4 protocol is not needed for gFilers because the storage subsystems provide disk protection. Most of the disk information in the Data ONTAP documentation does not apply to the gFiler because it is about RAID-4.

Volume

In Data ONTAP, volumes are the primary means of organizing and managing data. From the perspective of Data ONTAP, a volume is an identified collection of disks comprising a filesystem. From the perspective of a storage subsystem, a volume is an identified collection of LUNs on the storage subsystem. You manage data storage by managing volumes.

You can define more than one volume on a gFiler. You could, for example, create additional volumes to accommodate your users if they speak more than one language. For example, you could create one volume for files in French and another for files in German. See Chapter 6, Managing Volumes, RAID Groups, and LUNs for more information about creating and managing volumes.