That will be inaccurate because of cache... stuff written to disk just gets shoved into memory until the disk's ready. 30 gigs would probably fill the cache, but still, there's better ways that don't involve waiting for 30 gigs of data to be written.
Linux usually has the hdparm command. It has read tests that take just a few seconds:
There's no equivalent write-speed test but, for a traditional hard disk, read speed and write speed should be about the same.
If a file size increases in Linux/UNIX to say in GB's then will there be a decrease in write speed.
I mean will it take more time to write to a large file then to a small one??
Please clarify?
Thanks in advance (2 Replies)
I analysed disk performance with blktrace and get some data:
read:
8,3 4 2141 2.882115217 3342 Q R 195732187 + 32
8,3 4 2142 2.882116411 3342 G R 195732187 + 32
8,3 4 2144 2.882117647 3342 I R 195732187 + 32
8,3 4 2145 ... (1 Reply)
Hi,
We have smb client running on two of the linux boxes and smb server on another linux system. During a backup operation which uses smb, read of a file was allowed while write to the same file was going on.Also simultaneous writes to the same file were allowed.Following are the settings in the... (1 Reply)
Would simply like to write data (no audio) to a CD/RW disk. The disk drive states CD/RW on the front but don't know for sure if the software is configured to recognize it as a writable disk. I can read/move data from the disk to the hard drive with no issue from the disk. Any help in this... (4 Replies)
I am now on Kernel 2.6.32-26
For me 16x CD write speed is okay.
I have old hardware which was able to write DVDs at 1x, back in previous linux version.
Now, I dont get speed of less than 4x.
Tested on k3b, xfburn, and brasero. But all start at bottom 4x write speed. k3b forced back to... (0 Replies)
Hi,
I went to a computer store and the salesman sold me a SATA cable and told me that all SATA cables are the same. Another salesman at a different store told me a cable rated for SATA 2, which I bought, MIGHT work as well as one rate for SATA 3 but it is not guaranteed. I decided to run a... (3 Replies)
hi all:
as we know , when usb flash disk plug in and aotu mounted , the default permission of the usb flash disk is 700. that means others have no permission . the question: how to make others have read/write permission when the aotu mounted usb flash disk pluge in ? thanks !! (0 Replies)
Hi,
We have two servers in scenario (vmsoldot01 is Oracle VM with Linux and tldtppod15 is physical Linux server). One NAS share is mounted on both servers with similar permissions and access. But READ speed is too bad on virtual in comparison to physical server.
While trying to diagnose this, I... (2 Replies)
Hello All,
I am building a real time parser for a log file in my application.
The log file is continuously written at a very fast pace and gets rolled over every 10 minutes.
I have measured the speed and observed that around 1000 lines are written to it every second, each line about 30-40... (7 Replies)
Discussion started by: cool.aquarian
7 Replies
LEARN ABOUT SUSE
sg_raw
SG_RAW(8) SG3_UTILS SG_RAW(8)NAME
sg_raw - sends an arbitrary SCSI command (with an optional data phase) to a device
SYNOPSIS
sg_raw [OPTIONS] DEVICE CDB0 CDB1 ...
DESCRIPTION
This utility sends an arbitrary SCSI command (between 6 and 16 bytes) to the DEVICE. For the optional data phase, data can either be read
from a file and sent to the DEVICE or received from the DEVICE and then displayed or written to a file.
The SCSI command may be between 6 and 16 bytes long. Each command byte is specified in plain hex format (00..FF) without a prefix or suf-
fix. See EXAMPLES section below.
The commands pass through a generic SCSI interface which is implemented for several operating systems including Linux, FreeBSD and Windows.
OPTIONS
Arguments to long options are mandatory for short options as well.
-b, --binary
Dump data in binary form, even when writing to stdout.
-h, --help
Display usage information and exit.
-i, --infile=IFILE
Read data from IFILE instead of stdin. This option is ignored if --send is not specified.
-k, --skip=LEN
Skip the first LEN bytes of the input file or stream. This option is ignored if --send is not specified.
-n, --nosense
Don't display SCSI Sense information.
-o, --outfile=OFILE
Write data received from the DEVICE to OFILE. The data is written in binary. By default, data is dumped in hex format to stdout. If
OFILE is '-' then data is dumped in binary to stdout. This option is ignored if --request is not specified.
-r, --request=RLEN
Expect to receive up to RLEN bytes of data from the DEVICE. RLEN may be suffixed with 'k' to use kilobytes (1024 bytes) instead of
bytes. This option and --send are mutually exclusive.
-s, --send=SLEN
Read SLEN bytes of data, either from stdin or from a file, and send them to the DEVICE. This option and --request are mutually
exclusive.
-t, --timeout=SEC
Wait up to SEC seconds for command completion (default: 20). Note that if a command times out the operating system may start by
aborting the command and if that is unsuccessful it may attempt to reset the device.
-v, --verbose
Increase level of verbosity. Can be used multiple times.
-V, --version
Display version and license information and exit.
EXAMPLES
sg_raw /dev/scd0 1b 00 00 00 02 00
Eject the medium in CD drive /dev/scd0.
sg_raw -r 1k /dev/sg0 12 00 00 00 60 00
Perform an INQUIRY on /dev/sg0 and dump the response data (up to 1024 bytes) to stdout.
sg_raw -s 512 -i i512.bin /dev/sda 3b 02 00 00 00 00 00 02 00 00
Showing an example of writing 512 bytes to a sector on a disk is a little dangerous. Instead this example will read i512.bin
(assumed to be 512 bytes long) and use the SCSI WRITE BUFFER command to send it to the "data" buffer (that is mode 2). This is a
safe operation.
sg_raw -r 512 -o o512.bin /dev/sda 3c 02 00 00 00 00 00 02 00 00
This will use the SCSI READ BUFFER command to read 512 bytes from the "data" buffer (i.e. mode 2) then write it to the o512.bin
file. When used in conjunction with the previous example, if both commands work then 'cmp i512.bin o512.bin' should show a match.
EXIT STATUS
The exit status of sg_raw is 0 when it is successful. Otherwise see the sg3_utils(8) man page.
AUTHOR
Written by Ingo van Lil
REPORTING BUGS
Report bugs to <inguin at gmx dot de>.
COPYRIGHT
Copyright (C) 2001-2008 Ingo van Lil
This software is distributed under the GPL version 2. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR-
POSE.
SEE ALSO
sg_opcodes sg_vpd(sg3_utils), hdparm(hdparm), sgdiag(scsirastools)
sg3_utils-1.26 May 2008 SG_RAW(8)