Table of Contents
This chapter provides information on managing the storage components of a Data ONTAP 10.0 system, including disks, storage aggregates, and storage failover.
This section describes the following storage concepts:
Data ONTAP 10.0 systems currently support FC-AL and serial ATA disks.
Disk names take one of the following forms:
Disks that are not attached to a switch are named in the form node:host_adapter.loop_ID. For disks with a LUN, the form is node:host_adapter.loop_IDLLUN. For instance, disk number 16 on host adapter 1a on node node0a is named node0a:1a.16. The same disk on LUN lun0 is named node0a:1a.16Llun0.
Disks that are attached to a switch are named in the form node:switch_name:switch_port.loop_ID. For disks with a LUN, the form is node:switch_name:switch_port.loop_IDLLUN. For instance, disk number 08 on port 11 of switch fc1 on node node0a is named node0a:fc1:11.08. The same disk on LUN lun1 is named node0a:fc1:11.08Llun1.
The same disk can have multiple disk names, depending on the connectivity of disks in the Data ONTAP 10.0 system. For example, a disk known to a node named alpha as alpha:1a.19 can be known to a node named beta as beta:0b.37. All names are listed in the output of queries and are equally valid. To determine a disk's unique identity, run a detailed query and look for the disk's universal unique identifier (UUID) or serial number.
Disks on Data ONTAP 10.0 systems can use either RAID-DP™ (DP for Double Parity) or RAID Level 4. Both types of RAID ensure data integrity within a group of disks even if one or two of those disks fails.
An aggregate is a logical grouping of physical storage. It contains a defined amount of RAID-protected physical storage that can be expanded dynamically at any time. For example, if an aggregate is made up of three disks, an additional disk can be easily added to the storage pool, and the logical size of the storage pool can be increased accordingly, without disrupting any user or process currently using that aggregate. Each aggregate has its own RAID configuration and set of assigned disks. Aggregates can include hot spare disks that hold data if one of the other disks fails.
Data ONTAP 10.0 aggregates currently support only one plex per aggregate. See the documentation for Data ONTAP 7G or earlier for information about plexes.
Storage failover (SFO) provides an additional level of security that data continues to be served in the event of a hardware failure. Advantages of storage failover include the following:
No single point of failure in the storage solution. If a component of the RAID set fails, the RAID architecture ensures that another component takes over for it. Building on that capability, if a node fails in an SFO configuration, its failover partner takes over for it. Data and all management functions remain available regardless of a failure at any point in the system.
Less need for system-administration resources. If a failure occurs, the system automatically compensates and continues to serve data; no human intervention is required.
The components of storage failover include two nodes linked together in a failover pair. In an SFO configuration, two nodes share responsibility for a particular storage aggregate. If one node fails, the other automatically takes control of its disks and continues without losing any committed data. Additionally, virtual interfaces can be configured so that if a network port fails, the virtual interfaces are migrated to another port; see Chapter 8, Managing Virtual Interfaces for more information.