Chapter 1: System Tables

sysdevices

master database only

Description

sysdevices contains one row for each tape dump device, disk dump device, disk for databases, and disk partition for databases. There are four entries in sysdevices in the Adaptive Server distribution media: one for the master device (for databases), one for a disk dump device, and two for tape dump devices.

With Adaptive Server version 15.0, the device identification number is stored in the vdevno column and no longer as part of the high or low column. As a consequence, you may need to modify scripts and stored procedures that determine the device identification number based on the earlier schema.

Columns

The columns for sysdevices are:

Name	Datatype	Description
low	int	Not used for dump devices – block offset of virtual page in 2K bytes
high	int	Block offset of last virtual page in 2K bytes
status	smallint	Bitmap indicating type of device, default, and mirror status (see Table 1-9)
cntrltype	smallint	Controller type: Database device=0 Disk dump device or streaming tape=2 Tape dump device=3 – 8
name	sysname	Logical name of dump device or database device
phyname	varchar(127)	Name of physical device
mirrorname	varchar(127) null	Name of mirror device
vdevno	int	Device identification number
crdate	datetime null	Date on which the device was added
resizedate	datetime null	Date on which disk resize was most recently run for this device
status2	int	Additional status bits for this device (see Table 1-10)

The bit representations for the status column, shown below, are additive. For example, “3” indicates a physical disk that is also a default.

**Table 1-9: Bit representations for the status column.**
Decimal	Hex	Status
1	0x01	Default disk
2	0x02	Physical disk
4	0x04	Not used – logical disk
8	0x08	Skip header
16	0x10	Dump device
32	0x20	Serial writes
64	0x40	Device mirrored
128	0x80	Reads mirrored
256	0x100	Secondary mirror side only
512	0x200	Mirror enabled
1024	0x400	Master device is mirrored
2048	0x800	Used internally – mirror disabled
4096	0x1000	Used internally – primary device must be unmirrored
8192	0x2000	Used internally – secondary device must be unmirrored
16384	0x4000	UNIX file device uses dsync setting (writes occur directly to physical media)

Table 1-9 shows the bit representations for the status2 column.

**Table 1-10: Bit representations for the *status2* column.**
Decimal	Hex	Status
1	0x01	Direct I/O is enabled for this device

Indexes

Unique clustered index on name

View this book as PDF