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Introduction to the Teradata® RDBMS for UNIX® Version 2 Release 2.1 - NCR

NCR Introduction to the Teradata® RDBMS for UNIX® Version 2 Release 2.1 - NCR, 1998. - 315 p.
Download (direct link): inntroduktionteradata1998.pdf
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Introduction to the Teradata RDBMS for UNIX

9-7
Fault Tolerance Table Rebuild Facility

Table Rebuild Facility

This topic introduces the table rebuild facility available for the Introduction Teradata RDBMS.

The table rebuild utility is used to recreate a table, database, or Table Rebuild Facility 9 entire disk on a single AMP under the following conditions:

• Table structure or data is damaged because of a software problem, head crash, power failure, or other malfunction.

• Affected tables were enabled for fallback protection.

Table rebuild can create all of the following on an AMP-by-AMP basis:

• Primary or fallback portions of a table

• Entire table (both primary and fallback portions)

• All tables in a database

• All tables on an individual AMP

This utility is usually run by a System Engineer, Field Engineer, or Restrictions 9 System Support Representative.

The facility rebuilds a table only if fallback protection is enabled for that table.

9-8

Introduction to the Teradata RDBMS for UNIX
Fault Tolerance

Hardware Fault Tolerance

Hardware Fault Tolerance

The Teradata RDBMS provides several facilities for hardware fault

Introduction 9 tolerance. These are:

• Dual BYNETs
• RAID disk units
• Multiple channel and LAN connections
• Isolation from client hardware defects
• Battery backup
• Redundant power supplies and fans
• Hot swap capability for node components
• Cliques

Multinode Teradata RDBMS servers are equipped with two Dual BYNETs BYNETs.

Interprocessor traffic is never stopped unless both BYNETs fail. Within a BYNET, traffic can often be rerouted around failures.

Teradata RDBMS servers use Redundant Array of Independent Disk RAID Disk Units 9 (RAID) units configured for use as either RAID1 or RAID5 arrays.

JBOD is not a supported option.

RAID1 arrays offer mirroring (identical copies of data are maintained).

RAID5 arrays protect data from single disk failures with a 25 percent increase in disk storage to provide parity.

Multiple Channel and LAN Connections

In a client-server environment, multiple channel connections between mainframe and network-based clients ensures that most processing will continue even with one or several connections between the clients and server not working.

The migrating vproc feature is a software feature supporting this hardware issue.

Isolation From Client Hardware Defects

In a client-server environment, a server is isolated from many client hardware defects and can continue processing in spite of client defects.

Battery Backup

All cabinets have battery backup in case of building power failures.

Introduction to the Teradata RDBMS for UNIX

9-9
Fault Tolerance

Hardware Fault Tolerance

Redundant Power Supplies and Fans

Each cabinet in a configuration has redundant power supplies and fans to ensure failsafe operation.

Hot Swap Capability for Node Components

The following components are all offered with hot swap capability:

• RAID disks

• Fans

• Power supplies

Cliques

The clique is a feature of multinode systems that physically groups nodes together by multiported access to common disk array units. Internode disk array connections are made by way of SCSI buses. Shared SCSI-II paths enable redundancy to ensure that loss of a processor node or loss of a disk controller does not decrease data availability.

The nodes do not share data, only access to the disk arrays. Figure 9-4 illustrates a four node system.

Figure 9-4 Four node clique

Cliques are the physical medium that supports the migration of vprocs during times of node failure. If a node in a clique fails, then its vprocs migrate to another node in the clique and continue to operate while recovery occurs on their home node.

9-10

Introduction to the Teradata RDBMS for UNIX
Fault Tolerance

Hardware Fault Tolerance

PEs for channel-attached hardware cannot migrate. because they are dependent on the hardware that is physically attached to the node they are assigned to.

PEs for LAN-attached connections do migrate when a node failure occurs, as do all AMP vprocs. Figure 9-5 illustrates vproc migration during recovery from node failure.

Figure 9-5

How Vprocs Migrate After a Node Failure

To ensure maximum fault tolerance, do not locate any of the nodes in a clique within the same cabinet. For most purposes, this is an unnecessary precaution because of the battery backup feature, but if you want maximum fault tolerance, plan your cliques so the nodes are never in a common cabinet.

Introduction to the Teradata RDBMS for UNIX

9-11
Fault Tolerance

Hardware Fault Tolerance

The Administrative Workstation AWS provides a single system Single AWS System View view for 5100M (multinode) environments.

9-12

Introduction to the Teradata RDBMS for UNIX
Fault Tolerance

For More Information

For More Information

For more information on the topics presented in this chapter, see the following Teradata RDBMS manuals.
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