sp_helpdevice provides information about the devices in the sysdevices table.
When used without a device name, sp_helpdevice lists all the devices available on Adaptive Server. When used with a device name, it lists information about that device. Here, sp_helpdevice is used to report information about the master device:
sp_helpdevice master
device_name physical_name description ----------- -------------- ------------------------------------------ master d_master special, default disk, physical disk, 30 MB
status cntrltype vdevno vp_low vpn_high ------ ---------- ------- ------ ------- 3 0 0 0 10239
Each row in master..sysdevices describes:
A dump device (tape, disk, or file) to be used for backing up databases, or
A database device to be used for database storage.
The initial contents of sysdevices are operating-system-dependent. Entries in sysdevices usually include:
One for the master device
One for the sybsystemprocs database, which you can use to store additional databases such as pubs2 and sybsyntax, or for user databases and logs
Two for tape dump devices
If you installed auditing, there is a separate device for sybsecurity.
The vpn_low and vpn_high fields represent the page numbers that have been assigned to the device. For dump devices, they represent the media capacity of the device.
The status field in sysdevices is a bitmap that indicates the type of device, whether a disk device is used as a default storage device when users issue a create or alter database command without specifying a database device, disk mirroring information, and dsync settings. The status bits and their meanings are listed in Table 7-2:
For more information about dump devices and sp_addumpdevice, see Chapter 11, “Developing a Backup and Recovery Plan.”
| Copyright © 2005. Sybase Inc. All rights reserved. |
|
|
