I/O is an acronym for Input/Output, which refers to the mechanism or process for the transfer of information between one system or component and another.

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dd command: Finding read/write throughput of a flash/SD?

I am running petalinux from sd card. And trying to find data copying rate from Sd card and from QSPI flash that is there on the Xilinx Zynq board. As suggested here , I am doing like this: ...
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129 views

Can you throttle the bandwidth to a tmpfs based ramdisk?

I created a ramdisk using tmpfs as follows: sudo mount -t tmpfs -o size=1024m tmpfs /myramdisk I was looking into cgroup blkio subsystem bandwidth limits "read_bps_device" and "write_bps_device" ...
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503 views

GNU/Linux, IO performance problems

I have some problems with my system performance. As I was adviced here, I used sar: $sar -u 5 and found out that the problems are caused by a low HDD performance, as I supposed (high %iowait). ...
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103 views

Artificially prime buffer cache?

Is it beneficial to artificially prime the buffer cache when dealing with larger files? Here's a scenario: A large file needs to be processed, line by line. Conceptually, it is easy to parallelize ...
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37 views

pipe speed benchmark with machine readable output

I'm looking for a tool similar to pv which is producing machine readable output. And i cant believe that nobody did it bevore... I looked at the manpages of pv, pipemeter, dd and cpipe but all these ...
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1answer
90 views

How to customize or reprogram function of specific keys on my keyboard and the LED on my laptop

When I disable bluetooth on my laptop, the light does not go off and the blinking of the Wi-Fi LED is starting to bother me. Since I sometimes use my laptop in a poor lighting condition an illuminated ...
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66 views

Getting IO privileges in Linux

I have installed flashrom software. When i try to run sudo flashrom command it gives me "Could not get I/O privileges (Operation not permitted). You need to be root" error. Also I tried su command to ...
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244 views

CONFIG_GPIO_SYSFS makes /sys/class/leds disappear

I have an embedded Linux board I'm working on, with a button and a couple LEDs. By default, I can control the LEDs via /sys/class/leds/redled/brightness However, I have no way to monitor the ...
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24 views

Set ionice for a multi-threaded application

I have a program that spawns multiple threads, all of which do fairly intensive IO, running on the background. I want to set the scheduling class to idle so that it doesn't clog up the system; ...
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1answer
57 views

Very slow file operation

I recently rebuild a machine with Centos 5.8 with a brand new disk. This machine is old and has been running 5.8 for a long period with no issues so the only thing which changed recently is the new ...
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1answer
115 views

Strange problem with IO or file system or what?

On a SLES 11 SP2 32-bit system I'm seeing a strange problem. It's as if the OS can not open a file from the beginning of the file. Say I have a file that is 200 lines. If I cat or more or vi the ...
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1answer
147 views

Determine how much a process is using each disk?

How do I tell how much load a particular process is contributing to each of several available volumes/mounts? It seems that dstat only shows aggregate stats across all processes per disk, and iotop ...
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476 views

Unable to close a Luks partition

For backup purposes, I have "snapshotted" a LVM partition. This partition was crypted so I have opened this Luks partition (snapshot) in order to do my backup. The problem is that I have forgotten to ...
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55 views

View syscalls/kernel activity for I/O from a running process

I'd like to be able to view syscalls or kernel activity for a process...I'm not actually sure of the terminology I need here! Specifically I'm looking for the difference between I/O going to local ...
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0answers
24 views

Linux sound lags while copying from USB key

Why did I experienced sound skipping while copying a big file from my USB key onto my computer's drive? I monitored the system during this I/O operation: music was playing from Internet on the ...
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37 views

IO throughput lower when only a single process using the disk?

I am running a busy cacti server on centos and sometimes the rrdtool process is painfully slow when writing to disk, in HTOP the IO Column would display something between 100-300. I a polling cycle ...
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82 views

How to calculate blkio shares in cgroups?

Currently I'm trying to setup a test scenario with the use of Debian Wheezy with its default kernel 3.2.60-1+deb7u3 and the cgroups blkio controller. The calculation of blkio.weight is not working for ...
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212 views

/dev/sda not appearing after secure erase

I decided to wipe my SSD with a secure erase before installing Arch Linux, since the Arch wiki said that it would improve performance. I followed the instructions listed on the wiki, but now when I ...
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606 views

`crontab -e` sometimes fails with “Creation of temporary crontab file failed”

From time to time crontab -e fails on me on a Ubuntu box. It is the same for all users including the root and crontab -eu <user> under the root. Goes like this on a regular basis, a success here ...
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188 views

jbd2 journal constant i/o

iotop reports a constant i/o about 3% of [jbd2/vda1-8], I think this is the journal manager for ext4. my fstab is: UUID=X / ext4 defaults,noatime,nodiratime 1 1 tmpfs /dev/shm ...
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1k views

find ount what [flush-8:0] is writing

Using iotop, I found out that [flush-8:0] is doing a lot of hard disk activity, which explains the annoying slowdowns. However, I can't figure out what's the actual cause behind this flushing. No ...
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160 views

Shorter timeout on I/O errors MacOS X

How do you set a shorter timeout value for read/write I/O errors on MacOSX? We tend to get a few semicrashed disks and want to rsync the contents to a secure location, but when the file subsystem ...
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Inherit IO redirections from a script to another

When I redirect the output of a script within a script, I expect the redirection to be applied to the called script as well as the program called within it. A: ./B 2>> error.log B: ...
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Linux Mint keyboard and mouse take a long time to work after boot

I turn my computer on, select my linux harddrive, and then I end up at the Linux mint encryption password area. I have to wait about 1 minute just for my keyboard and mouse to actually light up and ...
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192 views

IOMMU causing freezes, disabling causes USB to not work

I'm somewhat new to linux, but I'm running a Xubuntu machine that I recently built. Since I started it up, I had noticed frequent freezes, where both the screen (if plugged in) and any SSH session ...
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How different is I/O handling of hard disk in AIX and Redhat Linux?

I am running a hadoop I/O workload in redhat linux and have ran that in IBM AIX as well with same underlying hardware, disk and disk configuration. With the default settings on the os redhat linux is ...
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How to set up ZFS with ZIL and L2ARC SSD?

I have been considering bcache and flashcache. However my friend suggested me something called ZFS. In fact it says that formating disk with ZFS can actually do the exact same thing without kernel ...
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30 views

stdin read notification

I want to detect when/if an application issues read(stdin, ...). Is it possible to use unbuffered I/O so that I could wait on write in external process? The problem: Some commands require user input ...
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148 views

Journal commit I/O error for Seagate Expansion external USB hard drive

I am using Debian 7.6 (amd64) and for some reason when I am trying to read or write to my Seagate Expansion 1TB external USB drive, I am getting input/output errors ... Here is what the output of ...
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44 views

Can ramdisk improve performance when stats show low wait and system cpu use?

I have jobs that do I/O of rates peaking around 200mb/s. On high load (over twice cpu cores) I tried to copy large file and got only few mb/s. Gathered dstat show single digits in wai and sys category ...
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188 views

Is swapping the cause of high IO on my box?

I'm running a LAMP stack on an Amazon EC2 micro instance with 616 MB of memory. This seems sufficient to be able to run a few small websites with Apache, MySQL and PHP. I have one Wordpress site ...