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Chapter 1: Commands

disk init

Description

Makes a physical device or file usable by Adaptive Server.

Syntax

disk init 
	name = "device_name" , 
	physname = "physicalname" , 
	[vdevno = virtual_device_number ,]
	size = number_of_blocks 
	[, vstart = virtual_address 
		, cntrltype = controller_number ] 
		[, dsync = { true | false } ]
	[, directio = {true | false} ]

Parameters

name

is the name of the database device or file. The name must conform to the rules for identifiers and must be enclosed in single or double quotes. This name is used in the create database and alter database commands.

physname

is the full specification of the database device. This name must be enclosed in single or double quotes. When the physical device path is relative, disk init returns a warning.

vdevno

is the virtual device number, which must be unique among the database devices associated with Adaptive Server. The device number 0 is reserved for the master device. Otherwise, valid device numbers must be between 1 and 2,147,483,647.

To determine the virtual device number, look at the device_number column of the sp_helpdevice report, and use the next unused integer.

size

is the amount of space to allocate to the new device. The following are example unit specifiers, using uppercase, lowecase, single and double quotes interchangeably: ‘k’ or “K” (kilobytes), “m” or ‘M’ (megabytes), “g” or “G” (gigabytes), and ‘t’ or ‘T’ (terabytes). Sybase recommends that you always include a unit specifier. Quotes are optional if you do not include a unit specifier. However, you must use quotes if you include a unit specifier. If you do not provide a unit specifier, the value provided is presumed to be in megabytes.

vstart

is the starting virtual address, or the offset, for Adaptive Server to begin using the database device. The following are example unit specifiers, using uppercase, lowecase, single and double quotes interchangeably: ‘k’ or “K” (kilobytes), “m” or ‘M’ (megabytes), “g” or “G” (gigabytes), and ‘t’ or ‘T’ (terabytes). Sybase recommends that you always include a unit specifier. Quotes are optional if you do not include a unit specifier. However, you must use quotes if you include a unit specifier. If you do not provide a unit specifier, the value provided is presumed to be in megabytes.

The size of the offset depends on how you enter the value for vstart.

The default value (and usually the preferred value) of vstart is 0. If the specified device does not have the sum of vstart + size blocks available, the disk init command fails. If you are running the Logical Volume Manager on an AIX operating system, vstart should be 2. Specify vstart only if instructed to do so by Sybase Technical Support.

cntrltype

specifies the disk controller. Its default value is 0. Reset cntrltype only if instructed to do so by Sybase Technical Support.

dsync

specifies whether writes to the database device take place directly to the storage media, or are buffered when using operating system files. This option is meaningful only when you are initializing an operating system file; it has no effect when initializing devices on a raw partition. By default, all operating system files are initialized with dsync set to true.

directio

allows you to configure Adaptive Server to transfer data directly to disk, bypassing the operating system buffer cache. directio is a static parameter that requires a restart of Adaptive Server to take effect.

Examples

Example 1

Initializes 10MB of a disk on a UNIX system:

disk init 
name = "user_disk", 
physname = "/dev/rxy1a", 
vdevno = 2, size = 5120 

Example 2

Initializes 10MB of a disk on a UNIX operating system file. Adaptive Server opens the device file with the dsync setting, and writes to the file are guaranteed to take place directly on the storage media:

disk init 
name = "user_file", 
physname = "/usr/u/sybase/data/userfile1.dat", 
vdevno = 2, size = 5120, dsync = true

Example 3

Creates a device named “user_disk” that uses directio to write data directly to disk:

disk init 
name = "user_disk", 
physname = "/usr/u/sybase/data/userfile1.dat", 
size = 5120, 
directio= true

Usage


Using dsync

NoteDo not set dsync to false for any device that stores critical data. The only exception is tempdb, which can safely be stored on devices for which dsync is set to false.

Standards

ANSI SQL – Compliance level: Transact-SQL extension.

Permissions

disk init permission defaults to System Administrators and is not transferable. You must be using the master database to use disk init.

Auditing

Values in event and extrainfo columns of sysaudits are:

Event

Audit option

Command or access audited

Information in extrainfo

20

disk

disk init

  • Roles – Current active roles

  • Keywords or optionsdisk init

  • Previous value – NULL

  • Current value – NULL

  • Other information – Name of the disk

  • Proxy information – Original login name, if set proxy in effect

See also

Commands alter database, create database, disk refit, disk reinit, dump database, dump transaction, load database, load transaction

System procedures sp_diskdefault, sp_dropdevice, sp_helpdevice, sp_logdevice





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