PRB: Sp_helpdevice Shows Multiple Devices with Device_number 0

ID Number: Q75546

1.10 1.11 4.20

OS/2

docerr

Summary:

SYMPTOMS

In the section for adding database devices (page 64 for version

1.11 and page 36 for version 4.2), the "Microsoft SQL Server System

Administrator's Guide" states that "VDEVNO" must be unique among

database devices and dump devices; running sp_helpdevice displays

multiple devices with the "device_number" equal to 0 (zero) (which

is reserved for the master device).

CAUSE

Unlike DISK INIT, which is used to create database devices, dump

devices are created with the stored procedure sp_addumpdevice,

which does NOT require a device number as a parameter. The stored

procedure sp_helpdevice calculates the "device_number" by dividing

the "low" column in sysdevices by 16777216. Because "low" (the

starting virtual page number) for dump devices is always 0 (zero),

this computation will yield 0 (zero).

For this reason, the master database device and all dump devices

have a device_number equal to 0 (zero) when running sp_helpdevice.

Additional reference words: 1.10 1.11 4.20