UNIX Configuration Guide:
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1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
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On |
On |
Off |
On |
On |
On |
On |
On |
Changing switch 3 to ON will disable the Media Recognition System, but this is not recommended.
The tape drive can be configured to operate in immediate mode and with infinite flush by setting switches 6 and 8 to OFF. This improves the drive's performance by reducing the time it takes to write filemarks and data because all commands will be treated as immediate. The drawback is that if power fails during a write operation, any data in the buffer will be lost.
The earliest version of HP-UX with which the drives can be used is as follows: The table below shows the earliest version of HP-UX from which the drives will connect:
HP-UX version |
HP SureStore Tape Products |
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If the DDS unit is correctly installed, the operating system kernel should already have the SCSI tape drivers configured. If you have any doubts, use the System Administration Manager (SAM) to check the kernel configuration.
Option |
Internal | |||
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Note: Set the value with the autoloader switched off.
For a more detailed explanation, please see Autoloader Option Switches.
Device files tell your host computer which system
hardware path to use when communicating with a specific
device and what type of device it is. The device files for
HP SureStore DAT drives are located in the directory
/dev/rmt
.
An HP-UX device file is made up of a Major Number and a Minor Number. Major Number recommendations for Series 700 workstations are as follows:
Each Major Number requires a different Minor Number
format as described below. To check the Major and Minor
Numbers on your workstation, use the lsdev
command and look for the entry for SCSI tape driver.
On a Series 700, use the following commands to create device files:
mknod
' if you are using HP-UX
9.x or below
mksf
' if you are using HP-UX
10.x
Refer to your system's online man pages for further information about these commands.
An HP-UX device file can be configured using the following parameters:
Normally the drive repositions the tape to BOT (Beginning of Tape) when the device file is closed. This is set by device file Minor Numbers using the "rewind on close" option. To prevent this repositioning to BOT, use device file Minor Numbers with the "no rewind on close" option. The no-rewind option is useful when creating and reading multiple-file tapes.
Berkeley and AT&T functional modes differ in "read only" close functionality:
In most cases, Berkeley mode should be used. It should
always be used with mt
.
Most HP SureStore DAT drives can read and write data using multiple data formats. (Note that the HP SureStore Tape 2000 does not have data compression capabilities.) Typically, different formats use different data densities. The following table shows the specific meaning of data densities with respect to DDS tapes.
Data Density: |
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Data Compression: |
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Write buffering (or immediate reporting) allows tape drives to indicate write completion as soon as data is received.This allows a tape device to achieve streaming (continuous media motion).
Device file Minor Numbers that set buffering cause write buffering (and hence streaming) to be enabled. Device file Minor Numbers that set no buffering cause write operations to be unbuffered (write completion is not indicated until the data has been written to tape).
Unbuffered mode is likely to reduce I/O performance and media capacity and cause the tape to make more passes over the tape head. This in turn reduces tape life. For this reason, the buffering option should normally be used.
Unbuffered mode is only available through device Major
Number 205
.
Data is written to tape in blocks. Device file Minor Numbers that set "variable" blocks cause data-block sizes to be determined by write system calls (each write system call causes one data block to be written to the tape). Normally, variable-length blocks are used.
Device file Minor Numbers that set fixed blocks cause data blocks of a consistent size to be written. The specific block size is determined by the tape device and the driver. In fixed-block mode, write system calls to a device file must be a specified number of bytes in length. Fixed-block mode can increase or decrease I/O performance and tape capacity (depending on the tape device and the specific fixed-block size).
Fixed-block size is only available through Major Number
205
.
Tapes usually contain a single partition (partition 0).
HP DDS tape devices support the division of a tape into two
partitions (two separate logical volumes, partition 1 and
partition 0). Media can be partitioned by using the
mediainit
command with "-p
"
option. Partition 1 is nearest to BOT (Beginning of Tape);
partition 0 is nearest to EOT (End of Tape).
If the last tape access was to Partition 0, the tape is not usually repositioned on an "open". However, device file Minor Numbers that set "partition 1" cause the tape to reposition to the beginning of partition 1 on an "open" when the tape contains multiple partitions and the last tape access was to Partition 0. If the last tape access was to partition 1, the tape is not repositioned on an "open" operation.
Tape partitioning and access to partition 1 require the
use of Major Number 54.
The HP-UX 10.0 device file naming convention is a generalized scheme that permits flexibility in specifying the format of data written to tape for several different tape technologies.
For DDS drives, however, the format in which data is written to the tape is restricted and determined by the combination of device type and DDS cartridge type, rather than by the format specified in the device filename. Hence a drive will write to and read from a tape in a format compatible with the tape; for example, a DDS-2 cartridge in a DDS-3 drive will be recorded and read as a DDS-2 cartridge.
An HP series 700 workstation running HP-UX 9.x should use Major Number 121 for which the Minor Number format is:
0xBBBTLD
Where the parameters are as follows:
BBB |
Type of SCSI bus; for example: | |
201 |
Core SCSI | |
207 |
Fast/Wide (F/W) SCSI | |
4S0 |
EISA SCSI ( | |
T |
Target (SCSI ID) | |
0-6 |
Valid range is 0 to 6. Set the target to the same SCSI ID as the hardware. The default SCSI ID is 3. Make sure that this does not conflict with other peripherals on the same SCSI bus. | |
7 |
Invalid (reserved for the host system or initiator) | |
L |
LUN (Logical Unit Number) and partition | |
0 |
LUN 0, partition 0 | |
1 |
LUN 1, partition 0 | |
8 |
LUN 0, partition 1 | |
9 |
LUN 1, partition 1 | |
D |
Device type-specific configuration parameters: | |
6 |
Berkeley, rewind on close, non-compressed | |
7 |
Berkeley, no rewind on close, non-compressed | |
E |
Berkeley, rewind on close, compressed | |
F |
Berkeley, no rewind on close, compressed |
% mknod /dev/rmt/3hcn c 121
0x20130F
This command line creates a device file the following options:
For HP-UX 10.x, use mksf (make special file) to create the device files for the tape drive. The mknod command is not recommended because it selects configuration options by directly setting bits in the Minor Number. With HPUX 10.0 and above, there are more configuration options than will fit in the device files Minor Number, so this direct set method is no longer possible. Use SAM to create device files using the Tape Device section of the Peripherals function.
To accommodate the additional configuration options available in HPUX10.x, the Minor Number contains a base set of options, while extended options are stored in a table of configuration properties. The Minor Number contains an index to this property table. The index is maintained by the tape driver and is not directly visible to the user.
The mksf command sets the Minor Number and modifies the property table as necessary. If the device configuration requirements are limited to the base set of options, the default property table should be correct. The base set of options is as follows:
See Device Configuration Parameters for more details of these.
All other configuration options are extended options that result in use of the property table.
You must put tape device files using extended
configuration options in the /dev/rmt
directory. This is necessary for proper maintenance of the
property table.
Note: Use the rmsf
command to clean
up the unused device files, otherwise the property table may
overflow and cause the mksf
command to fail.
For conventions in naming device files, see Device Filenames: HP-UX 10.0
54
, 121
Ideally, device filenames correspond to a devices instance and its properties, as shown below. However, some common tape backup applications have built-in default device names, and you may need to ignore the standard naming convention for device filenames in this case. The standard convention is:
Device File Type |
Standard Name |
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|
|
|
|
tar default |
|
mt default |
|
Where:
BBB |
Type of SCSI bus; for example: | |
201 |
Core SCSI | |
T |
Target (SCSI ID) | |
0-6 |
Valid range is 0 to 6. Set the target to the same SCSI ID as the hardware. The default SCSI ID is 3. Make sure that this does not conflict with other peripherals on the same SCSI bus. | |
7 |
Invalid (reserved for the host system or initiator) | |
L |
Logical Unit Number (LUN) | |
0 |
LUN0, partition 0 | |
1 |
LUN1, partition 0 | |
8 |
LUN0, partition 1 | |
9 |
LUN1, partition 1 | |
D |
Density | |
l |
low density (non-compressed) | |
m |
medium density (non-compressed) | |
h |
high density (compressed) | |
c |
very high density (compressed) | |
P |
Partition | |
omitted |
Partition 0 | |
p |
Partition 1 | |
C |
Close convention | |
omitted |
AT&T-style close | |
b |
Berkeley-style close | |
N |
Rewind mode | |
n |
no rewind on close | |
(omitted) |
automatic rewind on close |
205
The naming conventions defined in this section indicate the options used with each device. You can, however, create device files with names of your own choice.
For each tape device present, eight device files are automatically created for regular use when the system is initialized. (A ninth file can be created especially for use by system diagnostics.)
n
" and "b
"
options, use one of the naming conventions described
below. When the standard naming convention is used, these
four files contain the density specification
"BEST
". When the alternative convention is
used, these four files contain the density specification
"f0
".
n
" and "b
",
use the pre-HP-UX 10.0 device file-naming convention. The
names include an arbitrary number to distinguish this
tape device from others in the system, followed by the
letter "m
". They are created automatically
when the system is initialized.
Each of the files using the standard or alternative
naming conventions is linked to the corresponding device
file using the pre-HP-UX 10.0 naming convention. Thus, the
device files that use the pre-HP-UX 10.0 naming convention
typically provide the same functionality as the device files
which contain the density specification "BEST
"
or "f0
".
There are two naming conventions in HP-UX 10.0 for device special files:
/dev/rmt/c#t#d#[o] [z] [e] [p] [s[#]]
[w]<format>[c[#]] [n] [b]
mksf
command where
required.
/dev/rmt/c#t#d# [f#] [i#] [n] [b]
The options in the naming conventions are common to all
HP-UX 10.0 tape drivers. The c#t#d#
notation in
the device special filename derives from ioscan
output and is described in the man pages for
ioscan
and intro
. For options
unique to stape
go to
Driver-specific options for stape.
The options in the naming structure are as follows:
c# |
Instance number assigned by the operating system to the SCSI card | |
---|---|---|
|
Target address (SCSI ID) on a remote bus | |
|
Device unit number at the target address (SCSI LUN) | |
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Writes wait for physical completion of the operation before returning status. The default behavior (buffered mode or immediate reporting mode) requires the tape device to buffer the data and return immediately with successful status. (This option is not recommended as it increases head wear and decreases performance.) | |
|
Format used in writing data to tape. This field can have the following values: | |
BEST |
Highest capacity density or format will be used, including data compression, if the device supports compression. | |
NOMOD |
Maintains the density used for data previously written to the tape. Behavior using this option depends on the type of device. This option is only supported on DDS and 8 mm drives. | |
DDSx |
Selects one of the known DDS formats. It can be
used to specify | |
See "Tape Format" for more information. | ||
|
Write data in compressed mode on tape drives
that support data compression. If a number is
included, it specifies a compression algorithm
specific to the device. | |
|
No rewind on close. Unless this mode is requested, the tape is automatically rewound upon close. | |
|
Specifies Berkeley-style tape behavior. When the b is absent, the tape drive follows AT&T-style behavior. | |
|
Used for short filename notation only. Specifies the format (or density) value encoded in the Minor Number. The meaning of the value depends on the type of tape drive. Use 0 for the highest density on DDS drives. | |
|
Used for short filename notation only. Specifies
an internal property table index value maintained
by the tape driver, containing an array of
configuration options. The contents of this table
are not directly accessible. Use the
|
stape
(Series 700 Major Number
205
only)The following options (available only through the
property table) can be used in creating device special files
for tape drives which access the stape
driver:
o |
Suppresses diagnostic messages to console (available only through Major Number 212) |
e |
Exhaustive mode is enabled. When exhaustive mode is enabled, the driver will, if necessary, attempt several different configuration options when opening a device. The first attempt follows the Minor Number configuration exactly. If that fails, the driver attempts other likely configuration values. |
With exhaustive mode disabled (the default setting), the driver makes only one attempt to configure a device, using the configuration indicated in the Minor Number. | |
p |
Specifies tape partitioning (available only through Major Number 205) |
|
Specifies fixed-block mode. The optional number indicates the block size. If you omit the number, the driver selects a default block size appropriate to the device type. |
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For a device at SCSI card instance 1, target 2 (SCSI ID 2), LUN 0, with exhaustive mode enabled (see Driver-specific options for stape ), fixed block size of 512 bytes, DDS-1 density with compression, AT&T-style with no rewind on close, the standard device file special name would be:
/dev/rmt/c1t2d0es512DDS1Cn
For a system requiring short file names, the same device special file would be named:
/dev/rmt/c1t2d3i#n
Where #
is an index value selected by the
tape driver.
Use the lssf
command to determine which
configuration options are actually used with any device
file.