Questions tagged [io]
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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Monitoring disk IO on MTD devices
Is there a tool for monitoring disk IO on MTD devices? I'm using UBI on top of MTD, so could also monitor IO there if that's possible.
It seems like only an erase counter is available in UBI and ...
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What makes sfill so slow?
sfill -Illv makes a file with data from /dev/urandom until it fills the partition.
Making a large file like this takes a lot of time. iotop tells me it is writing about 1 MB/s.
Though dd if=/dev/...
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bash IO redirection, how du dup() STDERR?
Consider the following example:
exec 10>&2 # duplicate STDERR to fd 10
{ echo ok; inexistantcommand; } > /tmp/both 2>&1 10>/tmp/err
exec 10>&- # close fd 10
I expect /tmp/...
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bash IO redirection with tee, without complicated syntax, how it works?
One way to do implicit dup(2) in bash with the output in fd {10,11,12} in a real use-case and close it right after, based on this:
$ cat tags
desktop-19.9.0
foobar-1.2.3
desktop-22.9.0
mobile-24.10.0
...
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Bash IO redirection, open & close 'fd', can someone explain?
I try to understand this concept for years, with at this time some incomplete knowledge of this.
Is anyone here can make a kind of a tutorial or good explanations with examples on how to
open a new ...
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Gparted enable more logging
I cannot find a way for Gparted to produce more informative logs in the manual. What I am looking for is to find out why exactly did e cartain I/O operation fail (more details about the SCSI command ...
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I can't specify DD to overwrite a usb 2.0 at its theoretical speed limit
I'm trying to learn about filesystem and i/o operations in practice, i mean, acting in a conscious way and my task is to overwrite a USB 2.0 flash drive with the dd command in a Linux. But as dd is ...
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cgroup v2 io.max limit not applied
I can't seem to be able to apply io.max limit through cgroups v2 on Rocky Linux 9.
Setup:
# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
...
├─nvme0n1p5 259:5 0 444.9G 0 part
│ └─...
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How to get disk I/O activity by files and processes?
On Red Hat 8 I sometimes get huge disk I/O operations.
I can see disk I/O activities by using sudo iotop -oP command.
Output is:
PID | USER | DISK READ | DISK WRITE
---- ------ ----------- -----------
...
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How do I calculate the disk IO utilization percentage using the data from /proc/diskstats?
1 major number
2 minor mumber
3 device name
4 reads completed successfully
5 reads merged
6 sectors read
7 time spent reading (ms)
...
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Isolating I/O issue with NVME or hardware?
Hardware:
Samsung 980 PRO M.2 NVMe SSD (MZ-V8P2T0BW) (2TB)
Beelink GTR6, with the SSD in the NVMe slot
Since the hardware arrived, I've installed Ubuntu Server on it as well as a bunch of services (...
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Is there a GUI linux application that shows per mounted disk i/o transfer rate in a graphic?
Is there a GUI linux application that shows per mounted disk i/o transfer rate in a graphic?
(Like gnome-system-monitor do for the swap mount but for each mounted drive)
I'm looking for an application ...
user330163
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host hangs after cat /dev/null > bigfile.log
I found a big log file(2.7 TB) on my disk, so I decided to empty it with the following command:
cat /dev/null > bigfile.log
After I executed this cmd, I lost my ssh connection. When I logged in ...
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input redirection to common commands like userdel [duplicate]
Is it possible to use users.txt a file that contains some users to redirect the input to
userdel
like this
userdel < users.txt
my question applpies to these common commands not only userdel.
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Limit write speed on disk based on remaining free space (on linux)
Is there a way to limit the overall write speed on a disk based on its remaining free space?
For example, if it is 99% full limit the speed such as filling the remaining space would require an entire ...
luca
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What is the impact of different Linux I/O APIs on performance benchmarking of NVMe SSDs? (libaio vs SPDK vs io_uring)
I am benchmarking NVMe SSDs on my Linux server, with the aim to achieve the IOPS, BW and Latency values as mentioned in the product specifications.
I'm using FIO as workload generator, and used libaio ...
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How to write a one-page file to disk in one flush?
Say I have 4096 bytes of data that I want to save in a file. It should take exactly one page and can be flushed only once. However, if I do it using multiple calls to kernel i.e. write piece by piece, ...
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in linux, system is slowed very much and CPU 100% when I copy from (non-system-based) usb HDD to another usbHDD. Why?
in linux, system is slowed very much and CPU 100% when I copy from (non-system-based) usb HDD to another usbHDD. Why?
My CPU is 100%. I was told that CPU can be 100% without system be slowed down....
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Soft link will pass filename as 1st parameter to target?
https://github.com/adurbin/iotools
Original usage is:
./iotools rdmsr x xxxxx
when I doing:
ln -sf iotools rdmsr
then I can do:
rdmsr x xxxxx
Why??
because when doing soft linking, it will pass the ...
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When io util is relatively high, will Linux read and write hard disks return EIO?
When input/output util is relatively high, will Linux read and write hard disks return EIO?
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How to best control variability in fio for a reliable filesystem benchmark?
for a work project, I am tasked to create a benchmarking tool to measure the read/write performance of a physical device, which acts much like a database server. Currently I am focused on the ...
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why top command in linux shows high us and low wa while cp many large files simultaneously?
I am copying 10 large files(which may costs 1 hour) simultaneously, and I used top command to check the cpu usage, but I found out 100.0 us and 0.0 wa. shouldn't it be IO-bound instead of CPU-bound? I ...
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(Manjaro) My HDD is giving me I/O errors, smartctl isn't working, and I can't mount my encrypted root
Before my HDD unmounted during operation, I made a symbolic link to two folders on my NVMe, not touching the HDD at all. Not sure how relevant that is, but it's what I can think of happening shortly ...
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Why top is not reporting high %wa on too many write sys calls
My HTTP application suddenly started taking extra time to start up. During this phase, it loads the data from the disk to the in-memory data structure.
I doubt it is due to the extensive logging ...
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Is it possible to disable page caching on Ubuntu?
I am running an application on Ubuntu 20.04 which requires me to clear the page cache everytime I run it. Currently, I just run echo 1 | sudo tee /proc/sys/vm/drop_caches everytime before I run the ...
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Determine DISK IO for a specific process in linux
I have an application that I am working on a sorting algorithm for a large data set. I want to calculate the effect of I/O in this algorithm.
Does counting the number of reading and writing operations ...
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How to read the "Report I/O and transfer rate statistics" from sar in sysstat?
CONTEXT. Rhel 8.6, sysstat 11.7.3
GOAL. I need to obtain readable statistics in kb, MB or GB, of the data transferred in bandwidth from a website.
WHAT AM I DOING. The server where the website is ...
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SSD performance different results in dd and gnome-disk
I wanted to measure my SSD read/write performance and found some recommendations for using dd and gnome-disks. (from my understanding, hdpart is not relevant since it's not using the disk itself but ...
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How does the --bsize option in fio work?
Since fio is a benchmarking tool that for each run, should simulate a real I/O workload, how does the --bsize option fit with that? My understanding is that the filesystem has a set block size for ...
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Why not always use 'oflag=direct' in 'dd'?
Using oflag=direct in dd seems always to make operations much faster than either not using it, or using pv etc. to do the operation instead.
Under what circumstances might I not want to use oflag=...
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How to access virtual address via terminal in Ubuntu?
i'm trying to read & write to register by using the busybox devmem command.
I printed its base address from the driver's source code and received the following address:
0xffffff800bdd0000
I ...
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Debian 11 - How can i lower the load on my server?
I'm currently running a Debian 11 with a load average of 4.
I want to lower this load - But i don't really know where to start, like a first step on at least the analisis part...
It's a Docker Server, ...
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Is there an equivalent to /dev/stdout for file descriptors 3-255?
I know that one can often trick command line utilities that expect a file to pipe into stdout out by passing /dev/stdout as the file name.
I'm wondering whether it's possible to make a tool pipe to a ...
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How to list the I/O usage per disk?
Using iostat, I can get the processes that use up the disk and how much - but can't specify the disk
iostat -o
Using dstat, I can see usage per disk - but not the processes that use it.
dstat -tdD ...
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Is there necessarily an in-kernel copy in Linux zero-copy networking?
I see some Linux zero-copy networking example illustrations on the internet like the following ones:
The usual IO example:
Zero copy IO example:
I see it eliminates CPU copies; it also eliminates ...
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Question about transfer data between specific physical memory and NVME
I'm trying to transfer data from specific reserved physical memory to my NVME, IIUC, there are 3 steps:
In the kernel driver, the reserved-memory (specified physical address and size in dts) is ...
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Why Disk stats show many read operations when I measure NVME squance write with fio and mmap as ioengine
Here is my fio configure and report:
# cat fio-write.fio
[global]
name=fio-seq-writes
filename=test
rw=write
bs=1M
direct=0
numjobs=1
[file1]
size=1G
ioengine=mmap
iodepth=1
# fio --version
fio-3.30
...
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What is the behavior of O_APPEND with lseek: can you rewrite a file opened in O_APPEND?
The docs on man lseek say,
If the O_APPEND file status flag is set on the open file description, then a write(2) always moves the file offset to the end of the file, regardless of the use of lseek().
...
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Is this drive dead?
Frankly I don't know what to title this issue/question...
I have this one particular drive in my basic home server that is causing me headaches.
Just finished restructuring my media library (sorting ...
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device to discard browser session writes
I use the Brave browser (a fork of Chromium) which writes session state to disk every second, activity that needlessly wears my SSD.
I am never interested in restoring my browser session.Never. So I ...
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How do I make this parallel bash script more efficient?
I have a simple script involving afni command line tools that I am running in parallel from bash, but it is very disk I/O intensive and slows things down on our server (using only 2-3 out of the total ...
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commit argument in ext4 fs vs commit mount option in fstab
Target
Improve the I/O performance of ext4 file system, specifically.
Background
I got to know about noatime and commit mount options for fstab, and also a warning that the former can be a breaking ...
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How to limit IO bandwidth using systemd?
I'm trying to limit IO usage of a service (or process/command). (Limit for IO read/write on hardware device, not for network.)
I found IOAccounting from systemd:
systemd-run --scope --user -p "...
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Is there any way to achieve prioritized IO operations in Linux 5.xx?
I run a lot of long-lived and io-heavy processes in addition to interactive processes on my machine. Unfortunately, they slow the interactive operations down to a crawl despite my best efforts. I ...
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why is iotop showing "?err"
when I run iotop, the second column "PRIO" shows ?err everywhere.
What does this mean? I did not find any mention of err in the manual page.
I am using custom compiled kernel. Could it be ...
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dd: when is mandatory use bs and count together?
I am reading many tutorials about the dd command. There are some examples including the bs and count parameters. Some of them where each one is isolated over the other and other where both are used ...
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PCIE USB card not working. What's the missing "... resource 0 [io ...]" line in dmesg meaning?
Problem with 4x USB controller PCIE cards seems to be not correctly installed.
Situation: We want to use USB Vision cameras with USB adapter cards, providing as much bandwidth as possible. So we tried ...
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redirect TTY input to output without serial cable
I'm using simulation software for unix (ucsim) that runs two simulated programs that supposed to connect to each other via its own simulated serial ports.
The software provides me with these methods ...
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`rsync` deletes all after input/output error mapping
I'm running a rsync command between two servers with the following command:
rsync -auv -P --delete --delete-excluded --stats --progress -e "ssh -i ~/.ssh/$ssh_pkey -p $port -l $user" $...
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UIO instance of a device-tree subnode
I have the following device-tree node which is auto generated by Xilinx PetaLinux in a proper dtsi file (which cannot be modified):
axi_dma_0: dma@a0000000 {
#dma-cells = <1>;
...
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