sg_stream_ctl - send SCSI STREAM CONTROL or GET STREAM STATUS command
sg_stream_ctl [--brief] [--close] [--ctl=CTL] [--get] [--help] [--id=SID] [--maxlen=LEN] [--open] [--readonly] [--verbose] [--version] DEVICE
SG_STREAM_CTL(8) SG3_UTILS SG_STREAM_CTL(8)
NAME
sg_stream_ctl - send SCSI STREAM CONTROL or GET STREAM STATUS command
SYNOPSIS
sg_stream_ctl [--brief] [--close] [--ctl=CTL] [--get] [--help]
[--id=SID] [--maxlen=LEN] [--open] [--readonly] [--verbose] [--version]
DEVICE
DESCRIPTION
Sends a SCSI STREAM CONTROL or GET STREAM STATUS command to the DEVICE.
These commands, together with WRITE STREAM(16 and 32) and several
fields in the Block Limits Extension VPD page [0xb7] support the
streams concept. The stream commands were added in SBC-4 draft 8 (Sep-
tember 2015).
Both STREAM CONTROL and GET STREAM STATUS commands expect data from the
DEVICE (referred to as 'data-in'). In the case of STREAM CONTROL only
the 'open' (STR_CTL<--0x1) actually needs the data-in as it contains
the "Assigned stream id" if the open was successful. The assigned
stream id should be used by subsequent WRITE STREAM commands and ulti-
mately by the STREAM CONTROL close (STR_CTL<--0x2). Valid stream ids
are between 1 and 65535 inclusive.
OPTIONS
Arguments to long options are mandatory for short options as well.
-b, --brief
this option reduces the output of the GET STREAM STATUS command
to just one number (in decimal) per line sent to stdout. Those
numbers are the currently open stream ids. If an error occurs
then -1 is sent to stdout and error related messages are sent to
stderr. The default is to print more words (and fields) from the
GET STREAM STATUS response.
-c, --close
selects the STREAM CONTROL command and sets STR_CTL<--0x2 (i.e.
'close'). The --id=SID option should also be given because it
defaults to 0 which is not a valid stream id.
-C, --ctl=CTL
CTL is the value placed in the STR_CTL field of the STREAM CON-
TROL command (cdb). It is a two bit field so has 4 variants: 0
and 3 are reserved; 1 opens are new stream and 2 closes the
given stream id. '--ctl=1' is equivalent to '--open' while
'--ctl=2' is equivalent to '--close'.
-g, --get
selects the GET STREAM STATUS command. If the --id=SID option is
also given the the response starts lists open stream ids from
and including SID. If the --id=SID option is not given (or SID
is 0) then all open stream id will be returned in the response
(data-in) as long as the allocation length (defaults to 248
bytes which can be overridden by the --maxlen=LEN option) is
long enough. This is the default action of this utility (i.e.
GET STREAM STATUS command) if no "selecting" options are given.
-h, --help
output the usage message then exit.
-i, --id=SID
SID is a stream id, a value between 1 and 65535. It is used by
STREAM CONTROL (close) to identify the stream to close. It is
used by the GET STREAM STATUS command as the starting stream id
(from and including); so stream ids that are less than SID will
not appear in the response.
-m, --maxlen=LEN
LEN is the maximum length the response can be. It becomes the
ALLOCATION LENGTH field in both commands. The default (in the
absence of this option) is 8 bytes for STREAM CONTROL and 248
bytes for GET STREAM STATUS.
-o, --open
selects the STREAM CONTROL command and sets STR_CTL<--0x1 (i.e.
'open'). If the --id=SID option is given then it is ignored.
The user should observe the response as the "Assigned stream id"
is printed on stdout if the open is successful, if not '-1' is
sent to stdout and error messages are sent to stderr. If the
--brief option is also given then the only thing sent to stdout
is a number of the assigned stream id (1 to 65535 inclusive) or
'-1' if there is an error.
-r, --readonly
this option sets a 'read-only' flag when the underlying operat-
ing system opens the given DEVICE. This may not work since oper-
ating systems can not easily determine whether a pass-through
command is a logical read or write operation on the media (or
its metadata) so they take a risk averse stance and require
read-write type permissions on the DEVICE open irrespective of
what is performed by the pass-through.
-v, --verbose
increase the level of verbosity, (i.e. debug output).
-V, --version
print the version string and then exit.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+--------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+--------------------------+
|Availability | system/storage/sg3_utils |
+---------------+--------------------------+
|Stability | Pass-through uncommitted |
+---------------+--------------------------+
NOTES
There are no special read commands for streams. This implies that "nor-
mal" READs (6, 10, 12, 16 or 32) can be used. Note that when a stream
is closed, all resources associated with that stream id are removed,
apart from the data in the written LBAs. To make sure the reading back
data is not delayed too much by error recovery (in the presence of
media errors) the user may set the RECOVERY TIME LIMIT field (RTL,
units for non-zero values: milliseconds) in the 'Read-write error
recovery' mode page. This can be done with the sdparm utility.
The SCSI WRITE STREAM (16 and 32) commands can be found in the
sg_write_x utility in this package.
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from http://sg.danny.cz/sg/p/sg3_utils-1.46.tgz.
Further information about this software can be found on the open source
community website at http://sg.danny.cz/sg/sg3_utils.html.
EXIT STATUS
The exit status of sg_stream_ctl is 0 when it is successful. Otherwise
see the sg3_utils(8) man page.
AUTHORS
Written by Douglas Gilbert.
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright (C) 2018 Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO war-
ranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
POSE.
SEE ALSO
sg_vpd,sg_write_x(sg3_utils); sdparm(sdparm)
sg3_utils-1.43 March 2018 SG_STREAM_CTL(8)