st(7) DG/UX 5.4 Release 2.01 st(7)
NAME
st - access a SCSI tape drive
SYNOPSIS
/dev/rmt/st (adapname@devicecode (adapaddr[,adapid]),deviceid,d)
[compression] [density] [norewind]
DESCRIPTION
The st device driver accesses a Small Computer Systems Interface
(SCSI) tape drive. The currently supported models on your AViiON
system are:
Model # Description
6577 QIC-150 150MB 1/4" cartridge
6677 QIC-320 320MB/525MB 1/4" cartridge
6691 QIC-320 320MB/525MB 1/4" stand-alone
6590 8mm 2GB 5 1/4" helical scan SCSI tape drive
6586/6587 1600 bpi 1/2" autoload streaming reel-to-reel
6588/6589 6250/1600/800(optional) bpi 1/2" autoload streaming
reel-to-reel
6760/6761 8mm 5GB 5 1/4" helical scan SCSI-2 tape drive
6762 4mm 2GB 3 1/2" DAT SCSI-2 tape drive
7921 High capacity, high throughput SCSI-2 tape array
subsystem (CLARiiON)
The st device driver accesses these tape units via special file nodes
in /dev/rmt:
adapname The name of the SCSI adapter; currently supported
adapters are cisc, dgsc, insc, ncsc, and hada.
@devicecode The adapter's hexadecimal device code, preceded by the
@ character
adapaddr The adapter's hexadecimal address
adapid The adapter's SCSI ID (range 0-7, recommended 7 or 6).
Omit to accept the default ID 7.
deviceid The tape drive's SCSI ID (range 0-7)
d The tape drive's unit number (range 0-7)
compression For models that support data compression, c enables
and u disables compression. Compression is enabled by
default on models 6760, 6761, 6762, and 7921.
density For models that support different densities, h selects
high, m selects medium, and l selects low density
norewind n prevents the tape unit from rewinding to beginning
of tape (BOT) when closed.
See rmt(7) for a description of the character special device access
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st(7) DG/UX 5.4 Release 2.01 st(7)
method provided by st.
Model 6577 supports only fixed-length records of 512 bytes.
Attempted I/O to this model using a record size that is not a multi-
ple of 512 bytes will fail with an errno of EINVAL.
The other models support variable-length records up to 65,536 bytes.
Using Compression
Switching from uncompressed to compressed mode is allowed only when a
tape is at BOT. For example, if you disable compression for a
model 6761 tape drive and then, after a write operation, enable
compression without first rewinding the tape in the drive, you will
get an error message. Switching from compressed to uncompressed mode
is allowed without restriction.
Model 6590 and 6760/6761 Tape Exchange
The Model 6590 SCSI drive supports only low density, uncompressed
data. The Model 6760/6761 SCSI-2 drives optionally support both mul-
tiple densities and data compression. The Model 6590 drive can access
a tape that was produced in a Model 6760 or 6761 drive with low den-
sity selected and data compression turned off. Conversely, with low
density selected and data compression turned off, the Model 6760/6761
drives can access a tape produced in a Model 6590 drive.
SCSI-2 Soft Error Monitoring
Soft error reporting has been added for models 6760, 6761, 6762 and
7921. The system periodically checks the soft error rates for these
models. If the rates exceed predefined limits, one of the two mes-
sages listed below appears at the system console. The first is the
less serious. If you receive either message, try a new tape. If the
message persists, clean the heads. If the message still persists,
have the drive serviced.
Tape device at st(%s,%x,%x) encountered a high number of correctable
(soft) errors. Please observe the suggested maintenance schedule for
the drive.
Tape device at st(%s,%x,%x) encountered an unacceptably high number
of correctable (soft) errors. Please clean the tape drive and use a
known good tape. If you receive this message frequently, contact
your DG service representative.
In these messages, st(%s,%x,%x) indicates the access path of the con-
figured tape device where the problem is occurring:
st(cisc@28(FFFFF300,6),4,0) for example.
EXAMPLES
The following statement accesses any of the supported tape drives
listed above:
st(cisc@28(FFFFF300,6),4,0)
The tape drive uses SCSI adapter cisc; the adapter's device code is
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st(7) DG/UX 5.4 Release 2.01 st(7)
28; the adapter's address is FFFFF300; the adapter's ID is 6; the
tape drive's SCSI ID is 4; and the tape unit number is 0.
The following statement accepts the default adapter ID of 7, disables
data compression (u), and specifies no-rewind (n):
st(cisc@28(FFFFF300),4,0)un
FILES
/dev/rmt/*
SEE ALSO
rmt(7), cisc(7), dgsc(7), hada(7), insc(7), ncsc(7).
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