sg_test_rwbuf(8) [suse man page]
SG_TEST_RWBUF(8) SG3_UTILS SG_TEST_RWBUF(8) NAME
sg_test_rwbuf - Tests the SCSI host adapter by issuing write and read operations on a device's buffer and calculating checksums. SYNOPSIS
sg_test_rwbuf [--addrd=AR] [--addwr=AW] [--help] [--quick] --size=SZ [--times=NUM] [--verbose] [--version] DEVICE or an older deprecated format sg_test_rwbuf DEVICE SZ [AW] [AR] DESCRIPTION
sg_test_rwbuf writes and reads back SZ bytes to the internal buffer of DEVICE (e.g. /dev/sda or /dev/sg0). A pseudo random pattern is writ- ten to the data buffer on the device then read back. If the same pattern is found 'Success' is reported. If they do not match (checksums unequal) then this is reported and up to 24 bytes from the first point of mismatch are reported; the first line shows what was written and the second line shows what was received. For testing purposes, you can ask it to write AW or read AR additional bytes. OPTIONS
Arguments to long options are mandatory for short options as well. -r, --addrd=AR Read an additional AR bytes (than indicated by SZ) from the data buffer. Checksum is performed over the first SZ bytes. -w, --addwr=AW Write an additional AW bytes (than indicated by SZ) of zeros into the data buffer. Checksum is generated over the first SZ bytes. -h, --help Print out a usage message the exit. -q, --quick Perform a READ BUFFER descriptor command to find out the available data buffer length and offset, print them out then exit (without testing with write/read sequences). -s, --size=SZ where SZis teh size of buffer in bytes to be written then read and checked. This number needs to be less than on equal to the size of the device's data buffer which can be seen from the --quick option. Either this option or the --quick option should be given. -t, --times=NUM where NUM is the number of times to repeat the write/read to buffer test. Default value is 1 . -v, --verbose increase verbosity of output. -V, --version print version number (and data of last change) then exit. NOTES
The microcode in a SCSI device is _not_ modified by doing a WRITE BUFFER command with its mode set to "data" (0x2) as done by this utility. Therefore this utility is safe in that respect. [Mode values 0x4, 0x5, 0x6 and 0x7 are the dangerous ones :-)] WARNING: If you access the device at the same time (e.g. because it's a hard disk with a mounted file system on it) the device's buffer may be used by the device itself for other data at the same time, and overwriting it may or may not cause data corruption! HOWEVER the SPC-3 draft standard does state in its WRITE BUFFER command: "This command shall not alter any medium of the logical unit when data mode ... is specified". This implies that it _is_ safe to use this utility with devices that have mounted file systems on them. Following this theme further, a disk with active mounted file systems may cause the data read back to be different (due to caching activity) to what was written and hence a checksum error. EXIT STATUS
The exit status of sg_test_rwbuf is 0 when it is successful. Otherwise see the sg3_utils(8) man page. AUTHORS
Written by D. Gilbert and K. Garloff COPYRIGHT
Copyright (C) 2000-2006 Douglas Gilbert, Kurt Garloff This software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR- POSE. sg3_utils-1.23 January 2007 SG_TEST_RWBUF(8)
Check Out this Related Man Page
SG_WRITE_BUFFER(8) SG3_UTILS SG_WRITE_BUFFER(8) NAME
sg_write_buffer - send a SCSI WRITE BUFFER command SYNOPSIS
sg_write_buffer [--help] [--id=ID] [--in=FILE] [--length=LEN] [--mode=MO] [--offset=OFF] [--raw] [--skip=SKIP] [--specific=MS] [--verbose] [--version] DEVICE DESCRIPTION
Sends a SCSI WRITE BUFFER command to DEVICE, along with data provided by the user. In some cases no data is required, or data can be read from the file given in the --in=FILE option, or data is read from stdin when either --raw or --in=- is given. Some WRITE BUFFER command variants do not have associated data to send to the device, for example "activate_mc" ("activate deferred microcode"). OPTIONS
Arguments to long options are mandatory for short options as well. -h, --help output the usage message then exit. If used multiple times also prints the mode names and their acronyms. -i, --id=ID this option sets the buffer id field in the cdb. ID is a value between 0 (default) and 255 inclusive. -I, --in=FILE read data from file FILE that will be sent with the WRITE BUFFER command. If FILE is '-' then stdin is read until an EOF is detected (this is the same action as --raw). -l, --length=LEN where LEN is the length, in bytes, of data to be written to the device. If not given (and length cannot be deduced from --in=FILE or --raw) then defaults to zero. If the option is given and the length deduced from --in=FILE or --raw is less (or no data is pro- vided), then bytes of 0xff are used as fill bytes. -m, --mode=MO this option sets the mode field in the cdb. MO is a value between 0 (default) and 31 inclusive. Alternatively an abbreviation can be given. To list the available mode abbreviations give an invalid one (e.g. '--mode=xxx') or use the '-hh' option. -o, --offset=OFF this option sets the buffer offset field in the cdb. OFF is a value between 0 (default) and 2**24-1 . It is a byte offset. -r, --raw read data from stdin until an EOF is detected. This data is sent with the WRITE BUFFER command to DEVICE. The action of this option is the same as using '--in=-'. -s, --skip=SKIP this option is only active when --in=FILE is given and FILE is a regular file, rather than stdin. Data is read starting at byte off- set SKIP to the end of file (or the amount given by --length=LEN). If not given the byte offset defaults to 0 (i.e. the start of the file). -S, --specific=MS MS is the mode specific field in the cdb. This is a 3-bit field so the values 0 to 7 are accepted. This field was introduced in SPC-4 revision 32 and can be used to specify additional events that activate deferred microcode (when MO is 0xD). -v, --verbose increase the level of verbosity, (i.e. debug output). -V, --version print the version string and then exit. NOTES
If no --length=LEN is given this utility reads up to 8 MiB of data from the given file FILE (or stdin). If a larger amount of data is required then the --length=LEN option should be given. The user should be aware that most operating systems have limits on the amount of data that can be sent with one SCSI command. In Linux this depends on the pass through mechanism used (e.g. block SG_IO or the sg driver) and various setting in sysfs in the linux lk 2.6 series (e.g. /sys/block/sda/queue/max_sectors_kb). Downloading incorrect microcode into a device has the ability to render that device inoperable. One would hope that the device vendor veri- fies the data before activating it. If the SCSI WRITE BUFFER command is given values in its cdb (e.g. LEN) that are inappropriate (e.g. too large) then the device should respond with a sense key of ILLEGAL REQUEST and an additional sense code of INVALID FIELD in CDB. If a WRITE BUFFER command (or a sequence of them) fails due to device vendor verification checks then it should respond with a sense key of ILLEGAL REQUEST and an additional sense code of COMMAND SEQUENCE ERROR. All numbers given with options are assumed to be decimal. Alternatively numerical values can be given in hexadecimal preceded by either "0x" or "0X" (or has a trailing "h" or "H"). EXIT STATUS
The exit status of sg_write_buffer is 0 when it is successful. Otherwise see the sg3_utils(8) man page. AUTHORS
Written by Luben Tuikov and Douglas Gilbert. REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>. COPYRIGHT
Copyright (C) 2006-2011 Luben Tuikov and Douglas Gilbert This software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR- POSE. SEE ALSO
sg_read_buffer(sg3_utils) sg3_utils-1.33 August 2011 SG_WRITE_BUFFER(8)