Commonly used definitions according to Netapp (Taken from the TR-4056 – Best Practices with Exchange and Cluster Mode)
Cluster – a cluster is a group of connected nodes or storage systems that share a global namespace. The cluster can be managed as a single Vserver or multiple virtual servers, which
enhance performance and reliability, and provide scalability benefits as well
Command Line Interface (CLI) – The Cluster Mode CLI provides a command -based mechanism that is similar to the UNIX tcsh shell because it provides tab completion, advanced queries, patterns, and wildcards in UNIX style.
Epsilon – An extra partial weight configured to one node. It does not determine the master, but it helps to form a majority. The epsilon node is epsilon for the entire cluster and not just for the individual replicated database (RDB) units. It is manually configurable, but can change automatically.
To add an epsilon to a node, use the cluster modify command with –node and –epsilon parameters
HA Pair – A pair of nodes, or storage systems, redundantly configured to serve data for each other if one of the two nodes fails
High Availability – The recovery capability provided by a pair of nodes, or storage systems, called an HA pair, which are redundantly configured to serve data for each other if one of the two nodes fails
LIF – A LIF is a logical interface that is mapped to a physical port. A physical port (In 8.1.1) can have up to eight LIFs in Cluster Mode. A LIF is required to access a Vserver. The three types of LIFs include cluster management, node management, and data management for Vserver. (Also there is an Intercluster lif type)
QUORUM – A quorum is formed when a majority of the eligible nodes in a cluster are healthy and in contact with one another. There is one quorum per RDB ring at any given time. The node with the lowest site ID that is online is elected master, while the rest of the nodes are secondary RDB members
RDB – A replicated database that stores and maintains the data that manages the cluster. The operations in an RDB are transactional in nature. There are four RDBs, including VLDB, VifMgr,Management, and SpinAuth. This is the key to maintaining high-performance consistency in a distributed environment. Each RDB unit has its own replication ring.
Ring – A ring is made up of one master, which is a read/write database, and other read-only databases. The writes go to the master and are then replicated to others in the ring through the cluster network
SFO – An SFO is a storage failover. When two nodes are connected together, it makes an SFO pair. The SFO pair must be of the same controller model. It can be enabled from either node
VIF – A VIF is a virtual interface, as opposed to network ports, which are physical. There are three types of VIFs and ports, including management, cluster, and data. Four physical ports can be grouped into a single VIF.
VLDB – A VLDB is a volume location database. A VLDB contains index information about which D-blade owns a volume and serves an aggregate. VLDB content is cached on each N-blade to speed up the data path
Vserver (SVM) – A Vserver is a secure, virtualized storage server assigned to a single tenant
Blades: You’ll sometimes see the older term Blades used. This is a .com type naming to simply classify functional processes which manage different parts of the system
(From http://www.ontap8.com/clustered-ontap-basics-carry-overs-from-the-gx-lifestyle/ )
N-Blade – Network Blade
- Manage
- Network
- Protocols
D-Blade – Disk Blade
- Manage
- WAFL
- RAID
- Storage
CSM:Cluster Sessions Manager
It provides the communication between the N-blade and the D-blade. The N-blade uses the CIFS and NFS protocols on the front end and the D-blade uses FC protocol on the backend.
Their common language was a proprietary protocol called SpinNP, which is the protocol that CSM uses. A write request flows from a client;through the N-blade,CSM and the D-blade and to the disks.
(From http://www.ontap8.com/clustered-ontap-basics-carry-overs-from-the-gx-lifestyle/ )
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