NAME

sg_turs - send one or more SCSI TEST UNIT READY commands

SYNOPSIS

sg_turs [--help] [--low] [--num=NUM] [--number=NUM] [--progress] [--time] [--verbose] [--version] DEVICE

sg_turs [-n=NUM] [-p] [-t] [-v] [-V] DEVICE

DESCRIPTION

This utility sends one or more SCSI TEST UNIT READY commands to the DEVICE. This may be useful for timing the per command overhead. Note that TEST UNIT READY has no associated data, just a 6 byte command (with each byte a zero) and a returned SCSI status value.

This utility supports two command line syntaxes, the preferred one is shown first in the synopsis and explained in this section. A later section on the old command line syntax outlines the second group of options.

OPTIONS

Arguments to long options are mandatory for short options as well.

-h, --help: print out the usage message then exit.
-l, --low: when [--progress] is not being used, this utility tries to complete the SCSI TEST UNIT READY command(s) as quickly as possible. Usually it calls a library function to do each TUR (sg_ll_test_unit_ready). With this option it uses the lower level sg_pt interface (see sg_pt.h) to save a little time on each TUR.
-n, --num=NUM: performs TEST UNIT READY NUM times. If not given defaults to 1. These suffix multipliers are permitted: c C *1; w W *2; b B *512; k K KiB *1,024; KB *1,000; m M MiB *1,048,576; MB *1,000,000; g G GiB *1,073,741,824; and GB *1,000,000,000 . Also a suffix of the form "x<n>" multiplies the leading number by <n>. Alternatively a hex number may be given, prefixed by either '0x' or has a trailing 'h'.
--number=NUM: same as --num=NUM. Added for compatibility with sg_requests and other utilities in this package. The sg_request utility has taken over the role of polling the progress indication which was originally assigned to the TEST UNIT READY command. This is a change by T10.
-O, --old: Switch to older style options. Please use as first option.
-p, --progress: show progress indication (a percentage) if available. If --num=NUM is given, NUM is greater than 1 and an initial progress indication was detected then this utility waits 30 seconds before subsequent checks. Exits when NUM is reached or there are no more progress indications. Ignores --time option. See NOTES section below.
-t, --time: after completing the requested number of TEST UNIT READY commands, outputs the total duration and the average number of commands executed per second.
-v, --verbose: increase level or verbosity.
-V, --version: print version string then exit.

NOTES

The progress indication is optionally part of the sense data. When a prior command that takes a long time to complete (and typically precludes other media access commands) is still underway, the progress indication can be used to determine how long before the device returns to its normal state. Around SPC-3 T10 changed the preferred command for polling the progress indication from TEST UNIT READY to REQUEST SENSE (see the sg_requests utilty).

The SCSI FORMAT command for disks used with the IMMED bit set is an example of an operation that takes a significant amount of time and precludes other media access during that time. The IMMED bit set instructs the FORMAT command to return control to the application client once the format has commenced (see SBC-3). Several long duration SCSI commands associated with tape drives also use the progress indication (see SSC-3).

The DEVICE is opened with a read-only flag (e.g. in Unix with the O_RDONLY flag).

Early standards suggested that the SCSI TEST UNIT READY command be used for polling the progress indication. More recent standards seem to suggest the SCSI REQUEST SENSE command should be used instead.

EXIT STATUS

The exit status of sg_turs is 0 when it is successful (e.g. in the case of a mechanical disk, it is spun up and ready to accept commands). For this utility the other exit status of interest is 2 corresponding to the "not ready" sense key. For other exit status values see the sg3_utils(8) man page.

OLDER COMMAND LINE OPTIONS

The options in this section were the only ones available prior to sg3_utils version 1.23 . Since then this utility defaults to the newer command line options which can be overridden by using --old (or -O) as the first option. See the ENVIRONMENT VARIABLES section for another way to force the use of these older command line options.

-n=NUM: performs TEST UNIT READY NUM times. If not given defaults to 1. Equivalent to --num=NUM in the main description.
-N, --new: Switch to the newer style options.
-p: show progress indication (a percentage) if available. Equivalent to --progress in the main description.
-t: after completing the requested number of TEST UNIT READY commands, outputs the total duration and the average number of commands executed per second. Equivalent to --time in the main description.
-v: increase level of verbosity.
-V: print out version string then exit.

ENVIRONMENT VARIABLES

Since sg3_utils version 1.23 the environment variable SG3_UTILS_OLD_OPTS can be given. When it is present this utility will expect the older command line options. So the presence of this environment variable is equivalent to using --old (or -O) as the first command line option.

AUTHORS

Written by D. Gilbert