Download - M_14_1.00 Scalability And High Availability with demos and labs.pdf

7/27/2019 M_14_1.00 Scalability And High Availability with demos and labs.pdf

1/18

Module 14:

Scalability and HighAvailability


2/18

Overview

Key high availability features available in Oracle andSQL Server

Key scalability features available in Oracle and SQLServer


3/18

High Availability

High availability ensuring database and data areaccessible for the maximum amount of time

Initialization parameters or configuration options inOracle and SQL Server

Logical (add, remove, rename columns) and physical(rebuild, move, change storage parameters) structure oftables

Online index operations

SQL Server partitioning option


4/18

Clustering

Both Oracle and SQL Server offer Active/Passive (single instance)and Active/Active (multi-instance failover clustering) options inclustering. In Oracle, it is called Failsafe and Real ApplicationClusters (RAC); SQL Server refers to it as Failover Clustering

For Active/Passive clustering, Failsafe and Failover clustering areboth based on Microsoft Cluster Services (MSCS) containing asingle set of non-shared disks

For Active/Active clustering, Failsafe and Failover clustering utilize amulti-node configuration where each node has its own instanceconnecting to shared disks. However, the database can be openedby only one node at a time

Oracles RAC can also provide Active/Active clustering in a shared-everything architecture where multiple instances cansimultaneously access data from the same database


5/18

Standby Database

Both offer standby database which can be used foravailability and disaster recovery

In Oracle, Data Guard

In SQL Server, AlwaysOn, Database Mirroring, and Log Shipping

Standby databases are updated using archive logs inOracle and transaction logs in SQL Server

Shipping of logs to a standby server and theirapplication can be controlled to provide scope for

recovery from user errors in the primarySnapshots of mirrored database in SQL Server andlogical standby database in Oracle can be used for read-only purposes such as reporting, analysis, DSS


6/18

Database Mirroring

Software solution for increasing the availability of aspecific database

Consists of principal server, a mirror server, andoptionally a witness server

Witness server enables automatic failoverCan operate in either Synchronous or Asynchronousmode

Use views such as sys.database_mirroring,

sys.dm_db_mirroring_connections to monitor databasemirroring


7/18

Demonstration: Database Mirroring

In this demonstration you will learn to:

Prepare Database on Instances

Configure Database Mirroring

Execute Failovers Between Instances

Utilize the Mirror for Read-OnlyProcessing with Database Snapshots

Monitor Activity Between Instances


8/18

SQL Server 2012 AlwaysOn

NEW high availability and disaster recovery solutionAchieving required 9s

Availability Groups on multiple databases

Multi-subnet clustering supportHardware utilization and performance

Active secondaries (reporting, backup)

Reduced planned downtime

Windows Server Core support

Rolling upgrade support


9/18

SQL Server 2012 AlwaysOn Details

Failover Cluster Instances:

Flexible failover policy for cluster health detection

Indirect checkpoints

Availability Groups:Asynchronous or synchronous modes

Listeners for fast application failover

Flexible failover policy

Automatic page repair against page corruption

Encryption and compression for security and high

performance transport


10/18

SQL Server 2012 AlwaysOn Tools

T-SQL DDL statementsWizards

New Availability Group

Add database to Availability GroupAdd replica to Availability Group

Failover Availability Group

AlwaysOn Dashboard for Availability Group health view

Object Explorer Details for Availability Group info

PowerShell cmdlets for automation


11/18

Demonstration: AlwaysOn

In this demonstration you will learn to:Implement AlwaysOn Availability Groups


12/18

Replication Objects

Replication is a specialization of the distributed database conceptwhere copies of an object can be kept in multiple databases

Unlike clustering and standby databases, replication encouragessharing and distribution of individual objects rather than entiredatabases

Both Oracle and SQL Server provide multiple types of replicationbased on whether the replicas are read-only or updatable

Replicas are refreshed in full or updated using discrete transactionseither synchronously (multi-master) or asynchronously (all others)

Oracle Streams offers replication in three forms:

Multi-master replication multiple peer-to-peer updatable replicas

Materialized views each replica has a master site with variouspolicies on updating the replicas

Hybrids of replication and materialized views


13/18

Replication Types

SQL Server offers the following types of replication: Snapshot replication used mostly as read-only copies which are

completely refreshed periodically

Transactional replication kept up-to-date with immediate or

deferred updates from the master site. Copies are used mostly as

read-only and occasionally updated. Updatable subscribers

(immediate and queued), and peer-to-peer transactional replication

support updates at subscribers.

Merge replication similar to Oracles multi-master replication

where the autonomous sites are synchronized at regular intervals

Oracle and SQL Server offer sophisticated algorithms for conflictresolution among updatable replicas


14/18

Demonstration: Replication

In this demonstration you will learn to:Define the Roles of Replication

Define the Publication and Articles

Implement Peer-to-Peer Replication

Use the new Configure Peer-to-PeerTopology Tool


15/18

Scalability

Scalability is the ability to support very large databases (VLDB)and/or large volume OLTP

Memory areas in Oracle and SQL Server are dynamically resizedwithout restarting. The process is performed either automatically orby the DBA in Oracle, where it is automatically performed by theDBMS in SQL Server.

Oracle uses parallel query slaves and SQL Server uses workerthreads to provide interoperation and intra-operation parallelism inthe execution of DML and DDL. Both optimizers are parallel-aware.

Oracle and SQL Server scale well in the handling of userconnections through the use of shared server processes

Oracle and SQL Server offer many types and features for speedyaccess to large volumes of data. Examples are many types ofindexes, advanced I/O techniques and caching.

SQL Server supports NUMA and Hot Add CPU


16/18

Scalability and HA in Backup and Recovery

MTTR targets can be set for instance recovery by controlling the

checkpoint process in Oracle using FAST_START MTTR_TARGET

and in SQL Server using recovery interval option

The RMAN features available in SQL Server backup and restore

utilities are:

Parallelism in backup and recovery operations Incremental backups

Multiple granularities in backup and restore to reduce the amount ofrecovery needed

Point in time recovery

Choice of backup media and devices

Duplicating or cloning databases

Moving of data in logical units of tablespaces using transportable

tablespaces across multiple platforms in Oracle is found in SQL

Server through the attach and detach features for databases


17/18


18/18

Review

We defined high availability and the role it plays inmodern day businesses

We covered all the important high availability features inOracle and SQL Server. The major ones being failoverclustering, standby databases and replication.

We learned the meaning of scalability with respect toVLDB and OLTP environments

We examined several scalability features found in Oracleand SQL Server such as dynamic memory management,

parallel SQL, query rewrite