dt-usersguide.t

Linux磁盘测试的源代码,测试磁盘的读写性能

systems.  By default, the test file created is deleted before exiting,
but sometimes you may wish to keep this file for further examination,
for use as a pattern file, or simply for the read verify pass of another
test (e.g., reading the file via memory map API).
.EX
    Syntax:
        dispose=mode     Set file dispose to: delete or keep.
.EE
.nh 2 Dump Data Limit \&"\fIdlimit=\fP\&" Option.
This option allows you to specify the dump data limit used when data
compare errors occur.  The default dump data limit is 64 bytes.
.EX
    Syntax:
        dlimit=value     Sets the data dump limit to value.
.EE
.nh 2 Device Size \&"\fIdsize=\fP\&" Option.
This option allows you to specify the device block size used.  On
Tru64 Unix, the device block size is obatined automatically by an
OS specific IOCTL.  For all other systems, random access devices
default to 512 byte blocks.  You'll likely use this option with
C/DVD's, since their default block size to 2048 bytes per block.
.EX
    Syntax:
        dsize=value      Set the device block (sector) size.
.EE
.nh 2 Device Type \&"\fIdtype=\fP\&" Option.
.nh 2 Input Device Type \&"\fIidtype=\fP\&" Option.
.nh 2 Output Device Type \&"\fIodtype=\fP\&" Option.
These options provide a method to inform \fIdt\fP of the type of device
test to be performed.  Without this knowledge, only generic testing is
possible.
.HS
Special Notes:
.bu
On Tru64 UNIX systems, these options are not necessary, since this
information is obtained via the DECIOCGET or DEVGETINFO IOCTL's:
.bu
Although the program accepts a large number of device types, as shown
below, specific tests only exists for "disk", "tape", "fifo", and
"terminal" device types.  Others may be added in the future.
.bu
In the case of "disk" device type, \fIdt\fP reports the relative block
number when read, write, or data compare errors occur.
.bu
Also for "disk" devices, \fIdt\fP will automatically determine the
disk capacity if a data or record limit is not specified.  This is
done via a series of seek/read requests.
.bu
On each operating system supported, string compares are done on well
known device names to automatically select the device type.
For example on QNX, "/dev/hd" for disk, "/dev/tp" for tapes,
and "/dev/ser" for serial lines.
.bu
The device type gets displayed in the total statictics.
.LP
.EX
    Syntax:
        dtype=string    Sets the device type.
        idtype=string   Sets the input device type.
        odtype=string   Sets the output device type.
.HS
    The Valid Device Types Are:
        audio     comm      disk      graphics  memory
        mouse     network   fifo      pipe      printer
        processor socket    special   streams   tape
        terminal  unknown
.EE
Note:  Although \fIdt\fP does not provide specific test support for
each of the devices shown above, its' design makes it easy to add new
device specific tests.  Specific support exists for disk, fifo, pipe,
tape, and terminals. Support for "ptys" may be added in the future
as well.
.nh 2 Error Limit \&"\fIerrors=\fP\&" Option.
This option controls the maximum number of errors tolerated before the
program exits.
.HS
Special Notes:
.bu
The default error limit is 1.
.bu
All errors have a time stamp associated with them, which may be useful
for characterizing intermittent error conditions.
.bu
The error limit is adjusted for read, write, or data compare failures.
This limit is not enforced when flushing data, or for certain AIO wait
operations which are considered non-fatal (perhaps this will change).
.bu
A future release may support an "\fIonerr=\fP" option to control the
action of errors (e.g., loop, ignore (continue), or exit).
.LP
.EX
    Syntax:
        errors=value     The number of errors to tolerate.
.EE
.nh 2 File Limit \&"\fIfiles=\fP\&" Option.
This option controls the number of tape files to process with tape devices.
.HS
Special Notes:
.bu
During the write pass, a tape file mark is written after each file.  After
all files are written, 1 or 2 file marks will be written automatically by
the tape driver when the device is closed.
.bu
During reads, each file is expected to be terminated by a file mark and
read() system calls are expected to return a value of 0 denoting the end
of file.  When reading past all tapes files, an errno of ENOSPC is expected
to flag the end of media condition.
.bu
Writing tape file marks is currently not supported on the QNX Operating
System.  The release I currently have does not support the mtio commands,
and unfortunately the POSIX standard does \fBnot\fP define this interface
(the mtio interface appears to be a UNIX specific standard).  Multiple
tape files can still be read on QNX systems however.
.LP
.EX
    Syntax:
        files=value      Set number of tape files to process.
.EE
.nh 2 Terminal Flow Control \&"\fIflow=\fP\&" Option.
This option specifies the terminal flow control to use during testing.
.HS
Special Notes:
.bu
The default flow control is "xon_xoff".
.bu
When using XON/XOFF flow control, you must make sure these byte codes
(Ctrl/Q = XON = '\\021', Ctrl/S = XOFF = '\\023), since the program does
not filter these out automatically.  Also be aware of terminal servers
(e.g., LAT), or modems (e.g., DF296) which may eat these characters.
.bu
Some serial lines do \fBnot\fP support clear-to-send (CTS) or request-to-send
(RTS) modem signals.  For example on Alpha Flamingo machines, only one port
(/dev/tty00) supports full modem control, while the alternate console port
(/dev/tty01) does not.  Therefore, if running loopback between both ports,
you can not use \fIcts_rts\fP flow control, the test will hang waiting for
these signals to transition (at least, I think this is the case).
.LP
.EX
    Syntax:
        flow=type        Set flow to: none, cts_rts, or xon_xoff.
.EE
.nh 2 Record Increment \&"\fIincr=\fP\&" Option.
This option controls the bytes incremented when testing variable length
records.  After each record, this increment value (default 1), is added
to the last record size (starting at "\fImin=\fP", up to the maximum record
size "\fImax=\fP").
.HS
Special Notes:
.bu
If variable length record testing is enabled on fixed block disks and
this option is omitted, then "\fIincr=\fP defaults to 512 bytes.
.LP
.EX
    Syntax:
        incr=value       Set number of record bytes to increment.
    or  incr=variable    Enables variable I/O request sizes.
.EE
.nh 2 I/O Direction \&"\fIiodir=\fP\&" Option.
This option allows you to control the I/O direction with random access
devices.  The default direction is forward.
.LP
.EX
    Syntax:
        iodir=direction  Set I/O direction to: {forward or reverse}.
.EE
.nh 2 I/O Mode \&"\fIiomode=\fP\&" Option.
This option controls the I/O mode used, either copy, test, or verify modes.
The copy option was added to do a byte for byte copy between devices, while
skipping bad blocks and keeping file offsets on both disks in sync.  I've
used this option to (mostly) recover my system disk which developed bad
blocks which could not be re-assigned.  A verify operation automatically
occurs after the copy, which is real handy for unreliable diskettes.
.LP
.EX
    Syntax:
        iomode=mode      Set I/O mode to: {copy, test, or verify}.
.EE
.nh 2 I/O Type \&"\fIiotype=\fP\&" Option.
This option controls the type of I/O performed, either random or sequential.
The default is to do sequential I/O.
.HS
Special Notes:
.bu
The random number generator used is chosen by defines: RAND48 to
select srand48()/lrand48(), RANDOM to select srandom()/random(), and if
neither are defined, srand()/rand() gets used by default.  Refer to your
system literature or manual pages to determine which functions are supported.
.LP
.EX
    Syntax:
        iotype=type        Set I/O type to: {random or sequential}.
.EE
The seeks are limited to the data limited specified or calculated
from other options on the \fIdt\fP command line.  If data limits are
not specified, seeks are limited to the size of existing files, or to
the entire media for disk devices (calculated automatically by \fIdt\fP).
If the data limits exceed the capacity of the media/partition/file under
test, a premature end-of-file will be encountered on reads or writes, but
this is treated as a warning (expected), and not as an error.
.nh 2 Minimum Record Size \&"\fImin=\fP\&" Option.
This option controls the minimum record size to start at when testing
variable length records.
.HS
Special Notes:
.bu
By default, \fIdt\fP tests using fixed length records of block size
"\fIbs=\fP" bytes.
.bu
This option, in conjuntion with the "\fImax=\fP" & "\fIincr=\fP" control
variable length record sizes.
.bu
If variable length record testing is enabled on fixed block disks and
this option is omitted, then "\fImin=\fP defaults to 512 bytes.
.LP
.EX
    Syntax:
        min=value        Set the minumum record size to transfer.
.EE
.nh 2 Maxmimum Record Size \&"\fImax=\fP\&" Option.
The option controls the maximum record size during variable length
record testing.
.HS
Special Notes:
.bu
If the "\fImin=\fP" option is specified, and this option is omitted,
then the maximum record size is set to the block size "\fIbs=\fP".
.bu
This option, in conjuntion with the "\fImin=\fP" & "\fIincr=\fP" control
variable length record sizes.
.LP
.EX
    Syntax:
        max=value        Set the maximum record size to transfer.
.EE
.nh 2 Logical Block Address \&"\fIlba=\fP\&" Option.
This option sets the starting logical block address used with the \fIlbdata\fP
option.  When specified, the logical block data (\fIenable=lbdata\fP) option
is automatically enabled.
.LP
.EX
    Syntax:
        lba=value        Set starting block used w/lbdata option.
.EE
.HS
Special Notes:
.bu
Please do not confuse this option with the disks' real logical block
address.  See \fIdt\fP's "\fIseek=\fP" or "\fIposition=\fP" options to
set the starting file position.
.bu
Also note that \fIdt\fP doesn't know about disk partitions, so any
position specified is relative to the start of the partition used.
.LP
.nh 2 Logical Block Size \&"\fIlbs=\fP\&" Option.
This option sets the starting logical block size used with the \fIlbdata\fP
option.  When specified, the logical block data (\fIenable=lbdata\fP) option
is automatically enabled.
.LP
.EX
    Syntax:
        lbs=value        Set logical block size for lbdata option.
.EE
.nh 2 Data Limit \&"\fIlimit=\fP\&" Option.
This option specifies the number of data bytes to transfer during each
write and/or read pass for the test.
.HS
Special Notes:
.bu
You must specify either a data limit, record limit, or files limit to
initiate a test, unless the device type is "disk", in which case \fIdt\fP
will automatically determine the disk capacity.
.bu
When specifying a runtime via the "\fIruntime=\fP" option, the data limit
controls how many bytes to process for each pass (write and/or read pass).
.bu
If you specify a infinite "\fIlimit=Inf\fP" value, each pass will continue
until the end of media or file is reached.
.LP
.EX
    Syntax:
        limit=value      The number of bytes to transfer.
.EE
.nh 2 Munsa (DLM) \&"\fImunsa=\fP\&" Option.
This option is used on Tru64 Cluster systems to specify various distributed
lock manager (DLM) options with devices or files.
.LP
.EX
    Syntax:
        munsa=string     Set munsa to: cr, cw, pr, pw, ex.
.HS
    MUNSA Lock Options:
        cr = Concurrent Read (permits read access, cr/pr/cw by others)
        pr = Protected Read (permits cr/pr read access to all, no write)
        cw = Concurrent Write (permits write and cr access to resource by all)
        pw = Protected Write (permits write access, cr by others)
        ex = Exclusive Mode (permits read/write access, no access to others)
.HS
            For more details, please refer to the dlm(4) reference page.
.HS
Special Notes:
.bu
MUNSA is an obsolete Tru64 Cluster term which meant \fIMUltiple Node
Simultaneous Access\fP.  The new term is DAIO for \fIDirect Access I/O\fP.
.LP
.nh 2 Common Open Flags \&"\fIflags=\fP\&" Option.
.nh 2 Output Open Flags \&"\fIoflags=\fP\&" Option.