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Questions tagged [iowait]

72 questions
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Iowait on single HDD drive slows/blocks operations on all other (SSD) drives on a DELL R620 w/ PERC H310 Mini Mono controller

As the Dell forums are a veritable disaster I'm trying here in case somebody has some hints for me here :) We have a system with 3 drives: SSD for the OS SSD containing a ZFS pool backing LXD containers A "backup" storage HDD drive The system is…
Arni J
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iowait Bound Server - Load Calculations & Process Scheduling

I have a script I'm writing that runs badblocks against a disk shelf full of drives and I'm trying to understand the server load that develops and at what point the server load is critical in this usecase. I have generally held to the general…
Zenonk
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glusterfsd Ubuntu 18.04 high iowait issues

We're running gluster on two hypervisors running Ubuntu. When we upgraded from Ubuntu 14.04 to 18.04, it upgraded gluster from 3.4.2 to 3.13.2. As soon as we upgraded and since then, we've been seeing substantially higher iowait on the system, as…
kartik_subbarao
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Tool to generate IOWaits

In order to test our monitoring infrastructure, I'd like to generate enough IOs to trigger an alert. As the alert is based on IOWaits, I should find a way to 'overload' the IOs. I found an article about that using dd: dd if=/dev/zero…
E. Jaep
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CPU wait state (RAM) stats?

As far as I understand, the wa % stat displayed by top is the I/O wait (i.e. hard drive). Is there a way to get similar wait stats, but for when the CPU is waiting for memory? My server is pretty much always 0.0 wa, because I've got an NVMe SSD, and…
BenMorel
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Linux ext4 timeout in KVM guest

Both the host OS and the guest OS are Debian 8 amd64. The guest is a raw disk image stored at /srv/machines/web.img. The host has a backup script scheduled each night at 1:55am. Here is my backup…
Lucio Crusca
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Linux high iowait without block device activity

I'm having a hard time figure out the reason cause high iowait on my server. top: %Cpu(s): : 30.0 us, 5.4 sy, 0.0 ni, 53.9 id, 10.1 wa, 0.0 hi, 0.7 si, 0.0 st iostat: Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz…
forke
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Apache not serving static content concurrently

When tried to open multiple pages from Codeigniter based custom CMS on different tabs, the first tab loads, while the subsequent tabs wait for the first tab to complete, then sequence follows randomly, which is in synchronous. How do I bring in…
nuthan
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High iowait despite small amount of write/read

I'm not sure how to interpret this or the next steps, but why is IOWait so high when I have not written/read much from any devices? Background: I am a developer trying to find why the DB seems to be slow on a particular environment. iostat -tm 60…
Will
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Full core of iowait with no actual IO load

I'm having an issue with a box that is "randomly" gaining an entire core worth of iowait -- and as far as I can tell there isn't any IO load to go with it, as illustrated by iostat: avg-cpu: %user %nice %system %iowait %steal %idle …
zebediah49
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iowait high when uncompress file in EC2 instance (AWS)

this 2 days, i faced very weird problem. When i'm doing uncompress big file, the iowait become very high, more than 70% I do iotop and the result got 3 process with high IO gzip -d filename [flush-202:1] [jbd2/xvda1-8] when the process run, the…
runix
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Tracing down High Linux Load - HDD at fault or too many interrupts ? (ksoftirqd Time 437:44.13)

Server Stats: "cat /proc/version" Output Linux version 2.6.18-308.24.1.el5 (mockbuild@builder17.centos.org) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-52)) #1 SMP Tue Dec 4 17:43:34 EST 2012 ethtool eth0 Output: Settings for eth0: Supported…
Analog
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Why load increase ,ssd iops increase but cpu iowait decrease?

There is a strange thing on my server which has a mysql running on it. The QPS is more than 4000 but TPS is less than 20. The server load is more than 80 and cpu usr is more than 86% but iowait is less than 8%. The disk iops is more than 16000 and…
mq44944
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mysqld causing machine to lockup with high iowait

I've inherited a LAMP server running centos, which randomly hangs from time to time despite low web traffic. I've installed Server Density to monitor what's going on, and have found during a hang the following happens: There is a spike in iowait to…
Twelve47
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JVM hangs with 100 IO wait on Ubuntu Maverick (AWS EC2 xlarge instance)

Asked this question on on stackoverflow, reposting: Have an xlarge instance in AWS running 9 Tomcats with heaps from 256M to 4G. With Ubuntu 10.04 the box sporadically hangs for a few hours with huge run queue (30-40), and nothing on CPU, then…
Leon
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