Tape Definitions

There are three configuration parameters relating to tape configuration: TapeNum, Tapen and TapeDevTypen.

The TapeNum parameter defines the number of tape drives available on this database. For example:

TapeNum=2

The available tape drives are named Tape1, Tape2 and so on. A particular tape may be defined several times: once to define the device driver for the default density; and once for each additional density supported.

Note: On Windows, the appropriate tape driver must be installed.

The parameters Tape1, Tape2, etc. define the tape density and the device driver for the associated drive as follows:

Tapen{:density}=tape-device

n The tape drive number.

density The data density. If density is omitted it is set to the default for the device. density may be used to select compression used. See examples below.

tape-device One of the following:
- The path of the required tape device on the local host.
- A remote tape device definition.
- The path of a tape image – that is, a file or named pipe that will emulate a Reality tape device.
The parameters TapeDevType1, TapeDevType2 and so on define the tape type where:

1 = ½ inch tape (UNIX only)
2 = 8mm Exabyte tape
3 = ¼ inch (QIC) cartridge
4 = reserved
5 = DLT or 4mm (DAT) cartridge
8 = remote tape device
9 = tape image

The default tape type depends on your host type.

Note: These settings can be overridden by using the T-DEVICE TCL command.

Remote Tape Device Definitions

A remote tape device definition must have the following format:

host{;port};devicePath;type{;flags}

where:

host is the DNS name or TCP/IP address of the remote host. This can be any UNIX or Windows host that supports Reality (Reality does not need to be installed) and must be accessible via a TCP/IP LAN. It must also be running the Reality Remote Tape Server – this can be installed from the Reality CD (for details, refer to the Reality Client Components Installation Guide).

port is an optional port number to be used on the remote machine – default: 52001.

devicePath is the full path to the device on the remote host. Note that the device path must include any modifier required by the remote host (for example, no rewind, density).

type is the Reality tape type number of the drive on the remote machine.

flags Optional Reality Remote Tape specific flags:

A Asynchronous mode (default).

S Synchronous mode.

Data Encryption

If required, you can specify that the data you save should be encrypted by Reality, by appending :kencryptionKey to the tape device definition. encryptionKey is the item-id of an encryption key item in the REK file. For example:

/user1/daveh/image.rti:kMYENCKEY

encrypts the data in the tape image file /user1/daveh/image.rti using the encryption key item MYENCKEY.

Notes:

The block size used with encrypted tape devices must be a multiple of 8.
When restoring data that was saved using an encrypted tape drive, you must first load the source database's REK file (see LOAD-REK) and create an encrypted drive using the encryption key that was used when saving the data.

Tape Images

A tape image is an ordinary file or named pipe that is used to emulate a Reality tape device. This provides a method of saving Reality data to disk. Any file name may be used, but it is recommended that the .rti extension is used so that tape images can be easily identified. For compressed images, you could use the extension .rci.

Data Compression

If required, you can specify that the data in a tape image should be compressed, by appending :c{level} to the file name, where level is the required compression level. The compression level must be a number from 0 to 9, where 0 is no compression and 9 is maximum compression. The level parameter is optional; if omitted, compression level 2 is used. The recommended compression level, optimising compression and performance, is 2.

For example, /tmp/filsave.rti:c8 sets the compression level to 8 for the file /tmp/filsave.rti.

The CompressTapeImage parameter sets the default compression level for the database.

Note: For remote tape definitions, you can specify that compression should be performed remotely, by appending the compression level to the remote file name, or locally by appending it to the complete tape definition. for example

shadowfax;/tmp/filsave.rti:c8;9

compresses the data once it is received by the remote host, while

shadowfax;/tmp/filsave.rti;9:c8

compresses the data before transmission to the remote host.

File Size Limit

If necessary, you can specify a maximum size for your tape image file. When the maximum size is reached, a new file is started, thus dividing the tape image into multiple files. This might be necessary if:

The host file system has a maximum file size; for example, Windows FAT file system, which has a maximum file size of 2 Gigabytes.
The files will be archived on a medium with a limited capacity; for example, CDROM, which has a maximum capacity of 650 Megabytes.

The use of multiple tape images is transparent to the Reality tape commands (see Tape Operation and Commands).

To specify a maximum file size, appending :ssize to the filename, where size is the required maximum size. You can specify size in bytes or, by appending the appropriate suffix (K, M or G), in Kilobytes, Megabtyes or Gigabytes. For example, /tmp/filsave.rti:s650M sets the maximum size to 650 Megabytes for the file filsave.rti.

When you specify a maximum file size, the file name is used as a template for a series of names, as follows:

If your file name includes one or more question marks (?), these are replaced by a sequence number. For example, if you specify C:\temp\img??.rti, the file names used will be

C:\temp\img01.rti
C:\temp\img02.rti
C:\temp\img03.rti
etc.
If your file name does not include any question marks, the first file will use the name you have specified, and subsequent files will have sequence numbers appended to this file name. For example, if you specify C:\temp\img.rti, the file names used will be

C:\temp\img.rti
C:\temp\img.rti2
C:\temp\img.rti3
etc.

Tape Images on Windows

On Windows, tape images should preferably be saved on a local hard drive on the Reality host. If you need to save to a remote host, there are two methods you can use:

The preferred method is to use remote tape. You must install the Remote Tape Server on the remote host.
Alternatively, you can save to a Windows network share. However, this can normally only be done when running Reality from the command prompt. For it to work for remotely connected Reality users, the share must be configured as follows:
1. Log in to Reality using telnet (for example, use RealLink for Windows or the Windows telnet command).
2. Use the SYS TCL command to obtain a Windows command prompt.
3. Use the Net use command to create a networked drive for the remote share (see Windows help for details). For example, to map the share \\financial\letters to drive E:, enter:
```
net use e: \\financial\letters /persistent:yes
```
  Note the inclusion of the persistent option; this specifies that the drive should be reconnected at logon – that is, whenever a user logs on remotely.

Typical Configuration

The following shows a typical tape configuration entry for a Solaris host with a 4mm DAT drive, 2 x 8mm Exabyte drives, and a pointer to a remote 8mm tape drive on a host called shadowfax:

TapeNum=4
#
Tape1:800=/dev/rmt/0lbn
Tape1:1600=/dev/rmt/0mbn
Tape1:3200=/dev/rmt/0mbn
Tape1:6250=/dev/rmt/0mbn
TapeDevType1=5
#
Tape2:800=/dev/rmt/1lbn
Tape2:1600=/dev/rmt/1mbn
Tape2:3200=/dev/rmt/1hbn
Tape2:6250=/dev/rmt/1hbn
TapeDevType2=2
#
Tape3:800=/dev/rmt/2lbn
Tape3:1600=/dev/rmt/2mbn
Tape3:3200=/dev/rmt/2hbn
Tape3:6250=/dev/rmt/2cbn
TapeDevType3=2
#
Tape4=shadowfax;/dev/rmt/0hbn;2;A
TapeDevType4=8

Examples

A number of example configuration file entries are given below.

Solaris

½ Inch Tape

Tape1:800=/dev/rmt/0lbn
Tape1:1600=/dev/rmt/0mbn
Tape1:3200=/dev/rmt/0hbn # Actually 6250
Tape1:6250=/dev/rmt/0cbn # Compressed mode if supported
TapeDevType1=1

8mm (Exabyte)

Tape1:800=/dev/rmt/0lbn  # 2 Gbyte format
Tape1:1600=/dev/rmt/0mbn # 5 Gbyte format
Tape1:3200=/dev/rmt/0hbn # 5 Gbyte compressed
Tape1:6250=/dev/rmt/0cbn # 5 Gbyte compressed
TapeDevType1=2

Note: The mapping of ½ inch densities to 8mm densities is arbitrary and customer definable.

4mm (DAT)

Tape1:800=/dev/rmt/0lbn  # Standard format
Tape1:1600=/dev/rmt/0mbn # Compressed
Tape1:3200=/dev/rmt/0mbn # Compressed
Tape1:6250=/dev/rmt/0mbn # Compressed
TapeDevType1=5

Note: The mapping of ½ inch densities to 4mm densities is arbitrary and customer definable.

DLT

Tape1:800=/dev/rmt/0lbn  # low density
Tape1:1600=/dev/rmt/0mbn # low density compressed
Tape1:3200=/dev/rmt/0hbn # high density
Tape1:6250=/dev/rmt/0ubn # high density compressed
TapeDevType1=5
Notes:

The mapping of ½ inch densities to DLT densities is arbitrary and customer definable.

Actual capacities depend on the cartridge type used.

QIC150

Tape1=/dev/rmt/0mbn
TapeDevType1=3

AIX

Notes:

To specify the values for low and high density, use the UNIX smit utility.

For more details about tape configuration on AIX, refer to the man page for rmt.

½ Inch Tape

Tape1:800=/dev/rmt.5 # low density, no re-tension on open, no rewind on close

Tape1:1600=/dev/rmt.1 # high density, no re-tension on open, no rewind on close

Tape1:3200=/dev/rmt.1 # high density, no re-tension on open, no rewind on close

Tape1:6250=/dev/rmt.1 # high density, no re-tension on open, no rewind on close

TapeDevType1=1

8mm (Exabyte), DLT and 4mm (DAT) are similar. Note that the mapping of ½ inch densities to 8mm, DLT and DAT densities is arbitrary and customer definable.

QIC150

Tape1=/dev/rmt/0mbn
TapeDevType1=3

Linux

4mm (DAT)

Tape1:800=/dev/nst0
Tape1:1600=/dev/nst0l
Tape1:3200=/dev/nst0m
Tape1:6250=/dev/nst0la
TapeDevType1=5

Note: The mapping of ½ inch densities to 4mm densities is arbitrary and customer definable.

Windows

TapeNum=4
#
Tape1:800=\\.\TAPE0                     # Uncompressed
Tape1:1600=\\.\TAPE0c                   # Compressed
Tape1:3200=\\.\TAPE0c                   # Compressed
Tape1:6250=\\.\TAPE0c                   # Compressed
TapeDevType1=5                          # As appropriate
#
Tape2= shadowfax;/dev/rmt/1mbn;2        # Remote tape
TapeDevType2=8
#
Tape3=c:\daveh\image.rti:c2:s650M       # Compressed tape image, max. size 650 Mbytes
TapeDevType3=9
#
Tape4=%REALTAPE%
TapeDevType4=9

Defines tape unit 1 as a 4mm (DAT) device with various tape densities and tape unit 2 as the 8mm (type 2) device on the shadowfax host. Tapes 3 and 4 are defined as tape images.

Notes:

c indicates that compression is used, if available.

The mapping of ½ inch densities to 8mm densities is arbitrary and customer definable.

Reality tape numbers start at 1; Windows tape numbers start at 0.

TapeDevType 3 uses fixed size 512 byte blocks.

The REALTAPE syntax allow you to specify a tape image file by using an environment variable. This usage has largely been superseded by the use of T-DEVICE.

Remote Tape

Tape1= shadowfax;/dev/rmt/1mbn;2
TapeDevType1=8
#
Tape2= shadowfax;/users/pauls/image.rti;9:kKEY1   # Encrypted data in remote tape image.
TapeDevType2=8

Defines tape unit 1 as the 8mm (type 2) device on the shadowfax host.

Tape Image

Tape1=/user1/daveh/image.rti
TapeDevType1=9
#
Tape2=$REALTAPE
TapeDevType2=9
#
Tape3=/users/pauls/image.rti:c2:kKEY1	# Data compressed and encrypted.
TapeDevType3=9

Note: The REALTAPE syntax enables the image file to be specified by an environment variable. This usage has largely been superseded by the use of T-DEVICE.