High Availability Guide : High Availability Guide
  
High Availability Guide
The solidDB®High Availability (HotStandby) component increases the reliability of your database system, reducing downtime. HotStandby uses a “hot standby” approach, in which a second database server runs in parallel with the primary server and keeps an exact up-to-date copy of the data. If the primary database server fails, the High Availability Controller (HAC) makes a switch over to the secondary, transparently to applications and with no loss of committed transactions, and with minimal performance impact. Switchover times can be quite fast — as short as a couple of hundred milliseconds, depending upon the characteristics of your hardware and software environment.
This guide contains information specific to the HotStandby component only. For general administration and maintenance information about solidDB® databases, see solidDB® Administrator Guide.
This guide assumes the reader has general database management system (DBMS) knowledge, and familiarity with SQL and solidDB®.
Illustration conventions
This document contains several server diagrams depicting different scenarios in the HotStandby environment.
The table below provides an illustration key for the server diagrams:.
Symbol
Description
The rectangle represents the executing program, that is, the database server (engine) itself.
The cylinder represents the data, generally stored on disk. Alternatively, some or all may be stored in memory.
This symbol represents the transaction log (Txn Log), which is used in both database recovery and HotStandby.
A rounded rectangle represents a complete server with data and Txn Log. If the phrase Secondary server or Primary server is inside the rounded rectangle, then the server is a HotStandby server.
For simplicity, in some cases the cylinder that represents the data in the database is omitted. In some cases, the symbol is simplified even further to show just the rounded rectangle. Both icons are simplified representations of a server.
Typographic conventions
solidDB® documentation uses the following typographic conventions:
Format
Used for
Database table
This font is used for all ordinary text.
NOT NULL
Uppercase letters on this font indicate SQL keywords and macro names.
solid.ini
These fonts indicate file names and path expressions.
SET SYNC MASTER YES; COMMIT WORK;
This font is used for program code and program output. Example SQL statements also use this font.
run.sh
This font is used for sample command lines.
TRIG_COUNT()
This font is used for function names.
java.sql.Connection
This font is used for interface names.
LockHashSize
This font is used for parameter names, function arguments, and Windows registry entries.
argument
Words emphasized like this indicate information that the user or the application must provide.
Administrator Guide
This style is used for references to other documents. New terms and emphasized issues are also written like this.
File path presentation
Unless otherwise indicated, file paths are presented in the UNIX format. The slash (/) character represents the installation root directory.
Operating systems
If documentation contains differences between operating systems, the UNIX format is mentioned first. The Microsoft Windows format is mentioned in parentheses after the UNIX format. Other operating systems are separately mentioned. There may also be different sections for different operating systems.
Syntax notation conventions
solidDB® documentation uses the following syntax notation conventions:
Format
Used for
INSERT INTO table_name
Syntax descriptions are on this font. Replaceable sections are on this font.
solid.ini
This font indicates file names and path expressions.
[ ]
Square brackets indicate optional items; if in bold text, brackets must be included in the syntax.
1
A vertical bar separates two mutually exclusive choices in a syntax line.
{ }
Curly brackets delimit a set of mutually exclusive choices in a syntax line; if in bold text, braces must be included in the syntax.
...
An ellipsis indicates that arguments can be repeated several times.
. . .
A column of three dots indicates continuation of previous lines of code.