Disk formats

FDDRL supports disks with the formats KEY, NK2 and NK4.

FDDRL only ever copies or restores onto a disk which has the same format as the original disk, i.e. from KEY disks only to KEY disks, from NK2 disks only to NK2 disks, and from NK4 disks only to NK4 disks. In other words, FDDRL does not convert one format to another.

Before copying or restoring, FDDRL checks whether the format of the output disk matches that of the input disk. If the formats do not match, FDDRL proceeds as follows in accordance with the specification in the OVERWRITE-DISK operand:

• If a VSN or *SAME-VSN is specified, FDDRL rejects the output disk. The copy/restore run will not be started or will be aborted. You can then convert the output disk to the correct format by means of the VOLIN utility routine (see the “Utility Routines” manual [2]).

• If an MN or *SAME-UNIT is specified, FDDRL formats and initializes the disk automatically before it is used again.

• If *BY-OPERATOR is specified, FDDRL offers another mount option.

When accessing a disk to be processed, FDDRL automatically recognizes what format it has. It is therefore not necessary to specify the format.

There are various different allocation units, depending on the format. An allocation unit is the smallest possible unit of storage space that the system makes available when creating or extending a file. The following allocation units are supported for the formats KEY, NK2 and NK4 in BS2000:

Format	Allocation unit
KEY	6
NK2	6, 8, 64
NK4	8, 64

FDDRL always assigns the output disk the same allocation unit as the input disk.

If the output disk deviates from the input disk with regard to the DMS PAM keys or the allocation unit, the operator is requested to confirm the change. If no confirmation is given, the copy/restore run will be aborted or, if the output disk was requested with OVERWRITE-DISK=*BY-OPERATOR, FDDRL offers another mount option.

The format of the disk must be distinguished from the definition which was specified when the disk was initialized with VOLIN using the FORMAT operand (KEY, NK2, NK4). This is independent of whether or not space is provided on the disk for writing a PAM key. It is therefore perfectly feasible for a disk to be defined for use by DMS as an NK disk even if the formatting of the disk allows a PAM key to be written.