®

IBM Software Group

© 2005 IBM Corporation

Informix High Availability Features

John F. Miller III

IBM Software Group

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Overview

Backup and Restore New & Recent Features

Backup Options

Restore Options

Best Practices

High Availability Data Replication

Archive Validation

New and Recent HA Feature

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Recent Backup & Restore Features Point in Time Restore of a table from a backup Ontape improvements

No tape size Large file support in ontape Backup/restore using STDIO Support of External Backup & Restore New option to salvage log using ontape

Onbar Improvements More accurate space calculation for onbar backup Reading and dumping logical log using onbar Improved messages in bar activity log Better handling of command line options in onbar Sync Emergency boot file and sysutil database (onsmsync) Progress Feedback

Re Directed Restore Backup Verification Parallel Log Cleaning

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Backup Types

Serial Backup Archives the entire system at a single point in time using only one data

stream

Parallel Backup Archives the requested dbspace one at a time to N data streams

External Backup Allows a third party application to backup the database server while

maintain logical consistency

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Physical Backup

Level 0 (Full Backup) Backup of all used pages

Level 1 (Incremental Backup) Backup of all modified pages since last level-0 backup

Level 2 (Delta Backup) Backup of all modified pages since last level-1 backup

Level 1 and 2 backup is not supported using EBR

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Overview

Backup and Restore New & Recent Features

Backup Options

Restore Options

Best Practices

High Availability Data Replication

Archive Validation

New and Recent HA Feature

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Restore Options

Cold Restore Restoring the server when the database engine is offline

Warm Restore Restore of dbspaces which occur while the database engine is online

Mixed Restore A cold restore of set dbspaces followed by a warm restore of other dbspaces

Logical Restore Follows physical restore

Required

After onbar restore from parallel backup

Warm Restore

After cold whole system restore it is optional

Parallel logical recovery ON_RECVRY_THREADS

OFF_RECVRY_THREADS

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Restore Options Point-in-time Table and/or column Level Restore

Imported Restore Transferring an archive taken on one computer and restoring it on a

second computer

Point-in-Time Restore Restoring the entire system to a single point in time

Suspended Restore Ability to continue the restore if a restore client fails

Restartable Restore Allows the DBA to pickup the restore from the failure point

Re-Directed Restore Allows chunk pathnames to be changed while doing the

restore

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Backup and Restore Tools

ontape

On-Bar

External Backup and Restore

archecker

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Point in Time Table Level Restore (PITTLR)

Provide the customer with the ability to easily extract a set of tables, a table or a portion of a table from a level 0 archive to a user specified point in time.

The extracted data can be placed in an external table or on a table on the server of the user’s choice regardless of server version or machine type as long as the database server is listed in the sqlhost file.

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Benefits

Extract a table or set of tables

Filter the retrieved data

Retrieve just a subset of columns

Repartition the data

Data may be placed in the same version database or on a different database version with a different machine architecture

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Recovery of Lost Table

Extracts a table called test1:tlr from the most recent backup of dbspace1 and places the data in table test1:tlr

database test1;create table tlr (

a_serial serial, b_integer integer, c_char char(20), d_decimal decimal ) in dbspace1;

insert into tlr select * from tlr;

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Using External Tables

Extracts a table called dl:source_tab from the most recent backup of dbspace1 and sends the data in ASCII format with fields delimited to the file named /TMP/PIPE.

database d1;create table source_tab (cola int) in dbspace1;

create external table target_tab (cola int) USING (‘/TMP/PIPE’,

‘DELIMITED’);

insert into target_tab select * from source_tab;

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Distributed Restore

Extracts a table called test:source_tab from the most recent backup of dbspace1 and places the data on the database server rem_srv in the table target_dbs:tlr_1

database target_dbs;create table target_tab ( columns );

database test;create table source_tab ( columns ) in dbspace1;

insert into target_dbs@rem_srv.target_tab select * from source_tab;

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Ontape Features Backup at the Server level

Support for incremental backups

Manual or continuous logical log backup

Restore entire system or single dbspace

Backup is self describing

All data backup is from the archive start time or before

No longer required to set TAPESIZE

Backup & Restore using STDIO

Large file support in ontape

Support of External Backup & Restore

New option to salvage log using ontape

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Ontape

Databaseserver

Physical Log

Logical Logs

reserve pages

ontape

Backup Media

onconfigonconfig

online logonline log

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On-Bar Features Parallel backup and restore

System and dbspace level backup and restore

Support for incremental backups

Manual or automatic backup of logical logs

Instance point-in time recovery

Open interface for communication with storage managers (XBSA)

Re-Directed Restore

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OnBar Architecture

StorageManager

XBSA

onbar_d

onbar

sysutils

Databaseserver

Backup Media

onconfigonconfig

debug logdebug log activity logactivity log emergency Boot file

emergency Boot file

online logonline log

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External Backup & Restore (EBR) Features

External Backup and Restore

EBR allows administrators to make a consistent copy of their dbspaces using external tools

Used with many 3rd party backup products

Allows for both cold and warm restores

Basic Steps Block server at checkpoint Backup dbspace(s) using third party tools Unblock server

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Flash Copy

IDS

Informix Host

Storage Spaces and logs

FlashCopy Backups

IDSIDS

ISM Backup logs

on-bar

Production Server A

Requires Storage System Capability

Use EBR technique to block server for copy

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Remote copy using PPRC

Requires Storage System Capability

Uses EBR technique to block server for copy

Makes a flash copy on local storage

Establishes PPRC relationship between local and remote site

Makes multiple flash copy on remote site

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Remote Copy using PPRC

IDS

Logical Logs

Storage Spaces

ISM Logs

Informix Host

IDSIDS on-bar

Production Server A

FlashCopy B

PPRC

FlashCopy

PPRC Copy C

XBSA

FlashCopy D FlashCopy E ...

FlashCopy

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Overview

Backup and Restore New & Recent Features

Backup Options

Restore Options

Best Practices

High Availability Data Replication

Archive Validation

New and Recent HA Feature

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Best Practices

1.Planning

2.Planning

3.Planning

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What is a Successful Recovery?

“Successful” recovery is defined by your business needs

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Goals For Recovery

Determine acceptable recovery time How long can your business function without the data?

How long can your production system be down during a restore?

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Right, Fast or Cheap?

Choose Two!

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Recovery Strategy

Tune theStrategy

Analyze/Testthe Strategy

ImplementThe Strategy

SelectTools

Plan RecoveryGoals

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Overview

Backup and Restore New & Recent Features

Backup Options

Restore Options

Best Practices

High Availability Data Replication

Archive Validation

New and Recent HA Feature

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What Is HDR (High Availability Data Replication)?

Two identical servers on two identical machines

Primary server Fully functional server All database activity – insert/update/deletes, are performed on

this instance Automatically sends logs to secondary server

Secondary server Read only server : allows read only query Always in recovery mode Receives logs from primary and replay them to keep in sync with

primary

When Primary server goes down, secondary server takes over as Standard server

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HDR – Key points

Easy of administration and setup

Reduced downtime using DR switchover

Update interval

Automatic client redirection using DBPATH

Improved performance by using secondary as report server

Independent of geographic location

Indexes are locked when created on primary (till they are shipped to secondary)

No Replication of Blobspace blobs (only)

Non logged databases are not replicated

Benefits Limitations

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ontape –p / onbar –r -ponmode –d secondary Server-A

ontape –s –L 0 / onbar –b –L 0onmode –d primary Server-B

HDR Setup

B

Primary

Logs

1) Backup made of primary server2) Notify primary server identity of secondary 3) Physical restore backup on secondary server4) Notify secondary server identity of primary 5) Logical log transmission begins

Primary Secondary

A

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HDR – Normal Operations

B

Read-only

PrimarySecondary

A

Users reading and updating databaseCan be

Updated

Network LinkFor log Transmission

Running Reports

Log Buffers are transferred to

Secondary

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HDR – How it works

AcctTable

LogicalLogBuffer

Logical LogsWritten to Disk

Primary Secondary

ReceptionBuffer

RecoveryBuffer

Logical LogsWritten to Disk

AcctTable LogRecvr

drsecapply

HDR Buffer

DRINTERVALSets maximum time lag in seconds for HDR buffer transmission

Set to ‘-1’ for synchronous.

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PrimaryDownSecondaryStandard

Read-only

HDR Availability - Failover

B

Users reading and updating database

A

onmode –d standard

Running Reports (Not Any More!!)

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Down

B

A

1) Switch Server-B to primary mode

Standard

onmode –d primary Server-A

Primary

5) Automatically transfers current logs from primary and resume

4) Possibly restore offline/backed up logs

2) Physical restore of failed system (if media failure) or restart Server-A to last checkpoint time

ontape -poninit -PHY

3) Notify Secondary server-A identity of Primary server

onmode –d secondary Server-B

Recovery ontape -lSecondary

HDR Restart with NO Downtime

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HDR Configuration Parameters

DRINTERVAL Also decides sync or non-sync configuration

DRTIMEOUT Actual value is 4 times of this

DRAUTO Controls how the secondary should changes modes

DRLOSTFOUND

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HDR Threads

Main thread Primary: dr_prsend Secondary: dr_secrecv

Ping thread Primary: dr_prping Secondary: dr_secping

Index thread Primary: dr_idx_send (dr_btsend) Secondary: dr_idx_recv(dr_btrecv)

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Overview

Backup and Restore New & Recent Features

Backup Options

Restore Options

Best Practices

High Availability Data Replication

High Availability Data Replication

Archive Validation

New and Recent HA Feature

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Validating Archives

Does not have to be run on the same computer as the archive was taken

Uses very little space ~50MB

Both onbar and ontape

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Validation

onbar -v [ other options ]

Are my backups usable? Run a verification before you need to restore

After a restore fails Get some idea why the restore failed

Perhaps the data was inconsistent

Perhaps the data was incomplete

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What is actually validated

Format of each page on the archive is check (similar to oncheck -cd)

Tape control pages are sanity check

Each table is checked ensuring all pages of the table exist on the archive tape

Reserve page format is validated

Each chunk free list is verified

Table extents are checked for overlap

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Example of Archive Validation

Backup Validationonbar -r -v (IDS 7.3)

onbar -v (IUS 9.X)

Sample Output:1999-06-28 105444 23595  23594 /spare2/9.20/bin/onbar_d -v…Successfully connected to Storage Manager.…Begin backup verification of level 0 for rootdbs (Storage Manager copy ID 102).…Completed level 0 backup verification successfully.…/spare2/9.20/bin/onbar_d complete, returning 0 (0x00)

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Overview

Backup and Restore New & Recent Features

Backup Options

Restore Options

Best Practices

High Availability Data Replication

Archive Validation

New and Recent HA Feature

IBM Software Group

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Other Recent HA Features

Fast Restart Ensure logical recovery is limited in

time

External Directives The ability to add directives to SQL

statements without modifying the program

Re-Send Index In an HDR environment copy an

index from the primary to correct a corrupted index on the secondary

Drop and Create an index online Dropping or creating an index

without locking the table while user are modifying the table

Redundant Network Listeners Multiple listener can now monitor

a single network port

Single User Mode An administration mode in which

only user informix can connect to the database

HDR setup using EBR Using External Backup and

Restore to setup HDR

ER auto resync Automatically resync or repair

tables in ER

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Other HA Features

Database mirroring

Thread suspension

Online configuration tuning

Online index checking

Dynamic lock table allocation (avoiding out of locks)

Event Alarms – automatic notification of database events

Enterprise Replication

InPlace Alter Table

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Questions