Adaptive Server 15.0 greatly extends the allowable number of disk devices and the allowable number of 2K blocks for each device.
In pre-15.0 releases of Adaptive Server, a virtual page is described internally in a 32-bit integer: the first byte holds the device number (vdevno) and the succeeding three bytes describe the page offset within the device in units of 2K bytes (the virtual page number). This architecture limits the number of devices to 256 and the size of each device to 32 gigabytes—for a maximum storage limit of 8 terabytes in the entire server.
With Adaptive Server 15.0, the device number and the page offset are stored in separate 32-bit integers. The new architecture allows you to create up to 2,147,483,647 disk devices, each of which can be as large as 2,147,483,648 2K blocks or 4 terabytes.
Because of schema changes to the sysdevices and sysusages system tables,
you may need to modify scripts and stored procedures that access
these tables. The device identifier must now be obtained from the vdevno columns
of sysdevices and sysusages.
The high, low, and vstart columns
of these tables no longer store the device and virtual page number—they
store only the virtual page numbers.
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