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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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" ...
4
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1answer
27 views

understanding lsof during long operation on big file

Background I'm running Musicbrainz Picard to update a ~11M ogg file on a 500GB NTFS disk (Transcend StoreJet) connected via USB and mounted using autofs. The connection is through docking station. ...
4
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1answer
557 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). ...
3
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1answer
148 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 ...
2
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1answer
84 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 ...
2
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1answer
109 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 ...
2
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1answer
77 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 ...
2
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1answer
312 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 ...
1
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1answer
18 views

Monitor temperature/IO of NVMe drive

Is there a way to monitor temperature or reads/writes of and NVMe drive (in this case Intel 750). hdparm, udisksctl, smartctl, and hddtemp all seem to lack this capability, google searches have been ...
1
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1answer
65 views

Desktop completely freezing on I/O operations

In my old system, I was already having desktop freezes on some heavy I/O operations like apt-get dist-upgrade and copying 4 GB video files. But now, it has become a lot worse: any apt-get install is ...
1
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1answer
44 views

Linux buffer(1) program — replacement? useful?

I used to heavily use the buffer(1) program especially in talking to tape drives. Its a program made in the 1990's to essentially use a circular shared memory buffer to speed up I/O between two piped ...
1
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1answer
209 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
151 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 ...
3
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0answers
51 views

What could cause dropping cache to be extremely slow on a large cluster?

I'm attempting to time file I/O on my disks. In order to make sure all the I/O is happening off the hard drives and not from ram, before I time any read, I run a drop cache command. Specifically, I ...
3
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0answers
828 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 ...
2
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271 views

Disk I/O latency using /proc/vmstat file

How do I calculate disk read and write latency in Linux? Is it possible to do the calculation using /proc file system? I am using iostat and vmstat command. But I do not understand how the ...
2
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124 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 ...
2
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32 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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0answers
61 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 ...
2
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0answers
394 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 ...
2
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0answers
1k 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 ...
2
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301 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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2k 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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0answers
205 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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64 views

Linux: Why do init and systemd use so much I/O?

This is probably unanswerable. But maybe someone else will have this problem and find this question, append to it, or proffer an answer. I discovered the pidstat command with its -d option, today. ...
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36 views

Storage device trouble: IO errors but no bad sectors?

I have a lightly used spinning metal drive (internal) with some VMs on it. I'm running into IO errors while running a VM and upon closer examination I have found a virtual disk file that is reporting ...
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44 views

Samba system calls for reading/writing files from/to NAS issued from Windows desktop client

Windows desktop machine is connected via 1GB Ehternet cable to personal NAS (under development) with Ubuntu on it. While reading and writing files (> 1GB size) from/to NAS strace was conducted to ...
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32 views

Restoring in-memory/swapped page state on resume from hibernation

I'm a big fan of Linux's hibernation support, which works extremely well on all the (admittedly slightly older) hardware I've tried it on. I highly prefer it to full shutdown and power up. There's ...
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110 views

iowait monitoring in top on OSX/iMac

I'm trying to monitor the performance of a process on OSX 10 (iMac), specifically whether I/O is currently a bottleneck or not. I don't use the machine, hence I need something simple that the user can ...
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162 views

Disk benchmark IO depth clear out

When I'm manipulating over some benchmark tool I/O depth, what exactly am I changing? Let's say I have SATA disk on /dev/sda. If I run hdparm: root@linaro-gnome:~# hdparm -I /dev/sda | grep Queue ...
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47 views

Find amount of IO occurring over various NFS mounts

When I run netstat | grep nfs, I get the currently mounted nfs connections for a given host in a cluster. If there is massive io happening over 1 (or 2) of the connections, how can I monitor this? Is ...
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54 views

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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100 views

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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258 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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292 views

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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2k views

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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33 views

Why does hdparm and dd show two completely different results?

I have an external hard drive (/dev/sdc1) mounted at /mount1 When running hdparm -tT /dev/sdc1 I get: /dev/sdc1: Timing cached reads: 2246 MB in 2.00 seconds = 1123.75 MB/sec Timing buffered ...
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17 views

Diagnose input/output errors on a Truecrypt container

I have been trying to get a local repository located on a usb drive working on an air-gapped machine. The repository was created with apt-mirror on the same kind of system (ubuntu i386). Currently I ...
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14 views

how qemu interacts with guest os io requests?

the Linux io stack (eg the path of an io request) is something like this: now when such a guest OS is a Linux distro in qemu, the path is the same except in this case there is no disk and scheme is ...
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34 views

Dive into qemu source code to trace io requests

I searched a lot about qemu and read its documentation but could not find any explaining its I/O stack. Specifically, I want to know about how an I/O request is created and what path it travels to ...
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39 views

dd process real vs. sys time

I have two quad core workstations. One is based on Intel Atom x86_64 architecture (WS1). Another one is based on armv7l architecture (WS2). Both are running 3.10 kernel version. Identical busybox dd ...
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29 views

Why my disk is at full speed even though very little is written or read?

Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 429.60 9.00 170.20 2.00 2479.20 71.20 29.62 10.80 67.28 ...
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36 views

LVM Logical Volume (linear) best performance

As a system administrator, one thing I do very often is increase LV's size. In most cases I have to extend first the VG, adding a new disk (we are talking about virtual machines). I have got a lot of ...
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62 views

Linux huge IOPS difference - same disks

I've been investigating for some time regarding some IOPS issues I've been experiencing.. And my mind is getting crazy! I have two servers (one bought 2 weeks ago, another 1.5 years ago) that I ...
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26 views

SSD as write target during reads

I have a real-time application which always writes data to a RAID 10 HDD configuration in a sequential manner at around ~50 MB/s. It uses mmap and writing should never be blocked due to waiting I/O. ...
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29 views

IO benchmark tools block size impact?

Many IO benchmark tools (fio, dd, etc...) provide way to set block size. Lets say that I change 4K to 64k and test read/write on mounted SATA disk. I will get higher data throughput in sequential ...
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11 views

Can suspending lead to data loss on an external HDD?

Let's assume we have an external HDD using an ext4 filesystem, powered via USB. Some write is ordered on the external drive, not synced yet. Then the user wants to suspend the system. Provided no ...
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173 views

Why cancelled_write_bytes is different size than created/removed file?

I was wondering how field cancelled_write_bytes from /proc/[pid]/io works, so I've created a file (dd) and then deleted it (rm). I was expecting to see cancelled_write_bytes ~equal to file size while ...
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0answers
43 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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297 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 ...