Restoring Data

When restoring data which was created in a Pick compatible environment, or on any other D3 or Advanced Pick platform, special options may be required to restore that data to D3. Some of the considerations are listed below.

Tape Labels

Some systems create tapes with a label consisting of 80 bytes, some with 512 bytes, and some with no labels at all. Label size and format may be device and D3 version dependent.

Labels contain a variable number of characters up to 47, depending on the length of the Timedate stamp and Platform ID.

In D3 version 7.1.0, the label size for 8mm tape was changed from 512 to 80 bytes. Tapes created on earlier releases of D3 7.2.1 or AP can be read using this release by setting the label to 512 bytes.

To read D3 tapes on other platforms using an earlier release of D3 or Advanced Pick, the label size must be adjusted to 80 bytes.

Where n is the device number:

Tape Format

D3 uses two different device drivers when writing to tape:

For example: A 4mm tape may have been written using a 1/4" device driver. The system on which D3 is loaded must be capable of using alternate device drivers. The pick0 configuration file, from which you are migrating, must be modified in the tape lines to show usage of alternate drivers.

Blocking Factors

If a tape is not readable, consider whether the source and target systems use the same UNIX blocking factors. If the tapes were created with a fixed block size, or variable-length block size, they must be read in the same way.

For 4mm and 8mm tape, it is highly recommended that the default block size always be set to variable block size mode (0) because  you can only perform a file restore when the block size is set to 0 .

WARNING

Using the wrong tapes or blocking factors can destroy your file system. 

Restore Options

Tape compatibility restore options are:

Save Options

To restore accounts into D3, it may be necessary to generate a tape on the source system using source-specific options:

End-of-File Marks

There may be a difference between D3 and the source system with the End-of-File and End-of-Data marks on the tapes.

Frame Size

D3 uses a frame size of 4 KB for all UNIX platforms. If the frame size is not the same as that of the source system, restore options should include the frame size of the source system.

Examples:

The command below restores from a tape where the originating system had a frame size of 2 KB, for example a D3 7.3.x system.

restore-accounts (F2000

The command below restores from a tape where the originating system had a frame size of 1024. If this is not done, then potentially twice as much disk space (or more) will be allocated as is necessary.

restore-accounts (F1000

For mvEnterprise, mvPro, SEQUOIA Pro, and SEQUOIA Pick tapes, use:

restore-accounts (FQ4000

See Also

Migration Tips

Compatibility Settings