Chapter 6: Overview of Disk Resource Issues

Commands for managing disk resources

Table 6-3 lists the major commands a System Administrator uses to allocate disk resources to Adaptive Server and provides references to the chapters that discuss those commands.

**Table 6-3: Commands for allocating disk resources**
Command	Task	See
disk init name = "dev_name" physname = "phys_name"...	Makes a physical device available to a particular Adaptive Server. Assigns a database device name (dev_name) that is used to identify the device in other Adaptive Server commands.	Chapter 7, “Initializing Database Devices”
sp_deviceattr logicalname, optname, optvalue	Changes the dsync setting of an existing database device file.	Chapter 7, “Initializing Database Devices”
sp_diskdefault "dev_name"...	Adds dev_name to the general pool of default database space.	Chapter 7, “Initializing Database Devices”
disk resize name = “device_name”, size = additional_space	Dynamically increases the size of database devices.	Chapter 7, “Initializing Database Devices”
disk mirror name = "dev_name" mirror = "phys_name"...	Mirrors a database device on a specific physical device.	Chapter 2, “Mirroring Database Devices”

Table 6-4 lists the commands used in object placement. For information about how object placement affects performance, see Chapter 6, “Controlling Physical Data Placement,” in the Performance and Tuning Guide: Basics.

**Table 6-4: Commands for placing objects on disk resources**
Command	Task	See
create database...on dev_name or alter database...on dev_name	Makes database devices available to a particular Adaptive Server database. The log on clause to create database places the database’s logs on a particular database device.	Chapter 6, “Creating and Managing User Databases”
create database... or alter database...	When used without the on dev_name clause, these commands allocate space on the default database devices.	Chapter 6, “Creating and Managing User Databases”
sp_addsegment seg_name, dbname, devname and sp_extendsegment seg_name, dbname, devname	Creates a segment – a named collection of space – from the devices available to a particular database.	Chapter 8, “Creating and Using Segments”
create table...on seg_name or create index...on seg_name	Creates database objects, placing them on a specific segment of the database’s assigned disk space.	Chapter 8, “Creating and Using Segments”
create table... or create index...	When used without on seg_name, tables and indexes occupy the general pool of space allocated to the database (the default devices).	Chapter 8, “Creating and Using Segments”

Considerations in storage management decisions

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