CAMDD(8) FreeBSD System Manager's Manual CAMDD(8)
NAME
camdd - CAM data transfer utility
SYNOPSIS
camdd <-i|o pass=pass_dev|file=filename,bs=blocksize,[...]>
[-C retry_count] [-E] [-m max_io] [-t timeout] [-v] [-h]
DESCRIPTION
The camdd utility is a sequential data transfer utility that offers
standard read(2) and write(2) operation in addition to a mode that uses
the asynchronous pass(4) API. The asynchronous pass(4) API allows
multiple requests to be queued to a device simultaneously.
camdd collects performance information and will display it when the
transfer completes, when camdd is terminated or when it receives a
SIGINFO signal.
The following options are available:
-i | -o args Specify the input and output device or file. Both -i and
-o must be specified. There are a number of parameters
that can be specified. One of the first two (file or pass)
MUST be specified to indicate which I/O method to use on
the device in question.
pass=dev Specify a pass(4) device to operate on. This
requests that camdd access the device in
question be accessed via the asynchronous
pass(4) interface.
The device name can be a pass(4) name and unit
number, for instance "pass0", or a regular
peripheral driver name and unit number, for
instance "da5". It can also be the path of a
pass(4) or other disk device, like "/dev/da5".
It may also be a bus:target:lun, for example:
"0:5:0".
Only pass(4) devices for SCSI disk-like devices
are supported. ATA devices are not currently
supported, but support could be added later.
Specifically, SCSI Direct Access (type 0), WORM
(type 4), CDROM (type 5), and RBC (Reduced Block
Command, type 14) devices are supported. Tape
drives, medium changers, enclosures etc. are not
supported.
file=path Specify a file or device to operate on. This
requests that the file or device in question be
accessed using the standard read(2) and write(2)
system calls. The file interface does not
support queueing multiple commands at a time.
It does support probing disk sector size and
capacity information, and tape blocksize and
maximum transfer size information. The file
interface supports standard files, disks, tape
drives, special devices, pipes and standard
input and output. If the file is specified as a
"-", standard input or standard output are used.
For tape devices, the specified blocksize will
be the size that camdd attempts to use to write
to or read from the tape. When writing to a
tape device, the blocksize is treated like a
disk sector size. So, that means camdd will not
write anything smaller than the sector size. At
the end of a transfer, if there isn't sufficient
data from the reader to yield a full block,
camdd will add zeros on the end of the data from
the reader to make up a full block.
bs=N Specify the blocksize to use for transfers.
camdd will attempt to read or write using the
requested blocksize.
Note that the blocksize given only applies to
either the input or the output path. To use the
same blocksize for the input and output
transfers, you must specify that blocksize with
both the -i and -o arguments.
The blocksize may be specified in bytes, or
using any suffix (e.g. k, M, G) supported by
expand_number(3).
offset=N Specify the starting offset for the input or
output device or file. The offset may be
specified in bytes, or by using any suffix (e.g.
k, M, G) supported by expand_number(3).
depth=N Specify a desired queue depth for the input or
output path. camdd will attempt to keep the
requested number of requests of the specified
blocksize queued to the input or output device.
Queue depths greater than 1 are only supported
for the asynchronous pass(4) output method. The
queue depth is maintained on a best effort
basis, and may not be possible to maintain for
especially fast devices. For writes,
maintaining the queue depth also depends on a
sufficiently fast reading device.
mcs=N Specify the minimum command size to use for
pass(4) devices. Some devices do not support 6
byte SCSI commands. The da(4) device handles
this restriction automatically, but the pass(4)
device allows the user to specify the SCSI
command used. If a device does not accept 6
byte SCSI READ/WRITE commands (which is the
default at lower LBAs), it will generally accept
10 byte SCSI commands instead.
debug=N Specify the debug level for this device. There
is currently only one debug level setting, so
setting this to any non-zero value will turn on
debugging. The debug facility may be expanded
in the future.
-C count Specify the retry count for commands sent via the
asynchronous pass(4) interface. This does not apply to
commands sent via the file interface.
-E Enable kernel error recovery for the pass(4) driver. If
error recovery is not enabled, unit attention conditions
and other transient failures may cause the transfer to
fail.
-m size Specify the maximum amount of data to be transferred. This
may be specified in bytes, or by using any suffix (e.g. K,
M, G) supported by expand_number(3).
-t timeout Specify the command timeout in seconds to use for commands
sent via the pass(4) driver.
-v Enable verbose reporting of errors. This is recommended to
aid in debugging any SCSI issues that come up.
-h Display the camdd usage message.
If camdd receives a SIGINFO signal, it will print the current input and
output byte counts, elapsed runtime and average throughput. If camdd
receives a SIGINT signal, it will print the current input and output byte
counts, elapsed runtime and average throughput and then exit.
EXAMPLES
camdd -i pass=da8,bs=512k,depth=4 -o pass=da3,bs=512k,depth=4
Copy all data from da8 to da3 using a blocksize of 512k for both drives,
and attempt to maintain a queue depth of 4 on both the input and output
devices. The transfer will stop when the end of either device is
reached.
camdd -i file=/dev/zero,bs=1M -o pass=da5,bs=1M,depth=4 -m 100M
Read 1MB blocks of zeros from /dev/zero, and write them to da5 with a
desired queue depth of 4. Stop the transfer after 100MB has been
written.
camdd -i pass=da8,bs=1M,depth=3 -o file=disk.img
Copy disk da8 using a 1MB blocksize and desired queue depth of 3 to the
file disk.img.
camdd -i file=/etc/rc -o file=-
Read the file /etc/rc and write it to standard output.
camdd -i pass=da10,bs=64k,depth=16 -o file=/dev/nsa0,bs=128k
Copy 64K blocks from the disk da10 with a queue depth of 16, and write to
the tape drive sa0 with a 128k blocksize. The copy will stop when either
the end of the disk or tape is reached.
SEE ALSO
cam(3), cam(4), pass(4), camcontrol(8)
HISTORY
camdd first appeared in FreeBSD 10.2
AUTHORS
Kenneth Merry <ken@FreeBSD.org>
FreeBSD 13.1-RELEASE-p6 November 11, 2015 FreeBSD 13.1-RELEASE-p6
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