IO (or I/O) is an abbreviation for input/output, most commonly referring to disk input/output.

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How can I optimize the Windows file cache so flushing a file is faster?

I have a third-party, object-oriented database server running on a Windows Server 2003 x64 machine with 24 GB of RAM. Except for some system processes and monitoring tools, the database server is the ...
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810 views

KVM IO leads to high system load, WD Caviar Green (EACS)

I have Ubuntu 12.04 host running Linux 3.2.0-24-generic, libvirt 0.9.8-2ubuntu17, qemu-kvm 1.0+noroms-0ubuntu13. Host uses elevator=deadline, guests use elevator=noop. All KVM guests use virtio, no ...
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483 views

Multiple ip to single interface

i'm using openstack, but i think this is a more general problem. Actually i've a dedicated which comes with 1 ip address, i bought another one, and added using openstack's nova-manage cli. So now ...
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57 views

How can I decide up the nature of performed IO?

I am using Linux (3.2.12-3.2.4). I have few "syncer" processes which updates lots and lots SQLite db files in a loop. The database sizes vary from 1 MB to few GB. I have a "searcher" process which ...
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544 views

Heavy disk write on a Debian VPS gives “ata1: lost interrupt (Status 0x50)”

I have a new Debian VPS that appears to fail almost every time I run a heavy disk write test on ext4 filesystem. The filesystem goes to read-only mode and "ata1: lost interrupt (Status 0x50)" is ...
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2k views

Amazon RDS: What are IO Requests?

I have an RDS instance that is costing me a lot of money. From my account activity on amazon I see that the instance has had about 800,000,000 IO requests over the past 7 days. To give you a little ...
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3answers
703 views

I/O rate and CPU Eating up Server making terribly slow site

My server (Ubuntu 10.04 Lucid LAMP Stack) on linode (1024MB ram, 40 GB storage, 400 GB Transfer) is loading terribly slow. My site (WordPress) is relatively small (1.5 Gigs of mysql) and gets around ...
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896 views

How to monitor IO svctm with every 5 mins frequency using nagios?

I want to collect samples of iostat's svctm, await every 5 mins from all of my servers and store them in nagios. I want to get the values for what is happening in every 5 minutes (not since boot time, ...
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1k views

Should You Continue Polling Socket For Readiness After An EAGAIN or EWOULDBLOCK Error?

I am creating a web crawler with a multiplexed download manager using Linux epoll (Linux 2.6.30.x). I pick links from a database of over 40,000 domains (each domain having between 1 and 2000 urls), a ...
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1answer
497 views

Using ionice Over Cluster

Background: I use a computing cluster at work (4 slave nodes and 1 head node) that uses the SGE job scheduler. Recently we've been running jobs that do some heavy IO and it has been slowing down ...
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890 views

I/O intensive MySql server on Amazon AWS

We recently moved from a traditional Data Center to cloud computing on AWS. We are developing a product in partnership with another company, and we need to create a database server for the product ...
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59 views

Find out the most I/O loaded directory

Looking for ways to find out the most I/O loaded directory in windows. similar to the following in linux to pin point the problem/bottleneck directory. iostat -p 1 Thanks
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529 views

Nginx+apache2 ubuntu server crashed with several hundreds of visitors

I have Linode 768mb RAM server on Linode. And i have Wordpress blog. On my server installed ubuntu, nginx as frontend and apache2 as backend. And i have APC and memcache modules. Sometimes site is ...
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1answer
523 views

I/O and CPU differences between dedicated hosting and Amazon EC2

I'm looking to run a high population Minecraft server (150+ players online at a time). For those unfamiliar with the Minecraft server, it is a (non-multithreaded) application written in Java (some ...
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11answers
8k views

What creates CPU I/O wait but no disk operations?

I have CPU I/O wait steady around 50%, but when I run iostat 1 it shows little to no disk activity. What causes wait without iops? NOTE: There no NFS or FUSE filesystems here, but it is using Xen ...
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1answer
892 views

I/O Xen Server on disk filesystem ext4

I have a Xen Server 6.0 and one disk (2TB) report I/O error my vm is Centos 6.2 (filesystem ext4) end_request: I/O error, dev xvdc, sector 896084224 end_request: I/O error, dev xvdc, sector 896084312 ...
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1k views

monitor IO to tmpfs partition?

How can I monitor the write speed to a tmpfs partition. It does not appear in the output of vmstat or iostat. I am running several python processes that are writing heavily to tmpfs and contributing ...
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174 views

Sendmail greatly increases value of Total DISK WRITE

Sendmail is installed on the server. It sends an average of 6 emails at 3K per second and writes 18 files in /var/spool/mqueue-client. Because of this high disk writes iotop: Total DISK WRITE: ...
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1answer
259 views

How can I determine the specific file referenced by fs_usage, which is listed by block

I was investigating a problem on a Mac OS X 10.6.8 Server, where users were complaining of access slowdowns. Network throughput slowed to a crawl. It felt like the server was overburdened. System ...
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2answers
358 views

Detecting Disk Writes Linux

my webserver running centos 5.7 is showing quite a lot of disk write activity which I cannot explain really. I run a few websites on this server with the help of nginx and php-fpm and xcache. On the ...
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3answers
655 views

IOs reads writes per file

My target is to equally separate mysql database across the number of drives, using symbolic links on tables. Now I can not seem to find the way to check IOs, reads, writes per table on mysql. So now ...
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242 views

configuration for max read throughput on ssd: pcie vs sata vs raid

I'm looking to configure a storage setup, using ssd's, that will deliver the fastest read throughput on large (2+ GB) files on a 24 core (12 physical core) system. The data is static for the most ...
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862 views

Why does a CP command on linux consume CPU?

I just run a copy command for two large directories with a small number of huge files and I see my cp process is consuming around half a core in top: 51116 root 20 0 110m 876 688 D 43.9 ...
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1k views

Resource monitor and how to spot if you have disk I/O problems?

I have an application server which runs pervasive SQL and app using it. Last weeks the users are complaining about poor performace of the app and I suspect disk I/O problems because CPU and RAM ...
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155 views

wait rate very high due to mysql server activity

Sometimes the server is very slow and needs a lot of time for serving the requests. iotop shows a disk read rate of 1-2 M/S on average for some minutes (which is not that much actually), after that ...
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Is there a way to delete 100GB file on Linux without thrashing IO / load?

I have a huge log file I need to delete on a production web server. I'm worried it'll bring the system to a crawl if I rm it on Linux. Any brilliant ideas? Update: Filesystem: ext3 Partition: /var ...
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Logging hurts MySQL performance - but, why?

I'm quite surprised that I can't see an answer to this anywhere on the site already, nor in the MySQL documentation (section 5.2 seems to have logging otherwise well covered!) If I enable binlogs, I ...
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Is a 'high' IO rate healthy?

I do a lot of work with my Linode that currently hosts a site, but every now and then (usually once every two months or so) - I'll get a warning about my IO rate being too high (Usually just higher ...
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3k views

Reducing IO caused by nginx

I have a lot of free RAM but my IO is always 100 %util or very close. What ways can I reduce IO by using more RAM? My iotop shows nginx worker processes with the highest io rate. This is a file server ...
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1answer
203 views

Delay before download starts when serving files using nginx

I am currently using nginx to serve downloads off my website. Users sometimes need to wait about 5 seconds before their download starts after clicking a download link. I'm not sure if I need to start ...
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962 views

Try to delete files used by IIS

I got a service coded in c# whoes deleted somes web site files hosted on iis, before an update. But sometime when i delete the files, they stay there. If I try to delete them manually, via explorer, ...
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831 views

DB Server Disk I/O utilization

I have a Linux server that I use to run the DB of my application (MySql), the server have 8GB Ram and 4 cores. there are no other applications running on the server besides the MySql. Most of the ...
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monitoring disk i/o via wmi

I'm using WMI to monitor Windows Server 2003 and Windows Server 2008 hosts. I got all the info I wanted but the disk I/O performance. I've tried quering the ...
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1k views

5.5GB written daily to 1.2GB root volume - 4 times previous levels

Problem: I recently revamped one of my servers, it was tested prior to use, and functions well, however, a few days ago, I noticed approximately 4 times the usual amount of writes to the root volume. ...
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3answers
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High disk I/O activity in CentOS server

I have about 16 websites in a CentOS dedicated, and I am having some problems on high traffic hours, it seems to be a high disk I/O activity causing a general slowdown. I've installed atop and this ...
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713 views

How to track a single Xen VM's I/O utilization

What is a good way to monitor I/O individually for Xen Virtual Machines (not Dom0)?
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789 views

IO utilization percent of 4920.45% - iostat -x , What's wrong?

I have seen wrong percent use of a disk IO some times on servers that have been a long time without reboot. By any means this server has significant IO. Tonight it'll be rebooted and I'm sure ...
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168 views

How to analyze system calls when your disk is in read only and strace output is “Bus error”?

We have a HW problem with the disks, that made all the mount points to be read only. Output of dmesg: end_request: I/O error, dev sda, sector 15574609 sd 0:0:0:0: SCSI error: return code = 0x00040000 ...
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Utility for Monitoring IOPS on servers

We recently ran the Dell Performance Analysis Collection kit which monitors your servers via WMI for 24 hours. You send the file off to Dell and they return a report with graphs of IOPS and MB/S disk ...
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217 views

/etc/passwd continually accessed

I'm running a server on EC2 (Cent OS, 2.6.35.14, x86_64), and I recently went over my 1 million I/Os per month quota, which is absurd, as my disk utilization shouldn't be anywhere near that. (I'm not ...
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1answer
251 views

Good SAN sequential I/O throughput

We have an EMC San - CX4-240C filled with 15k (4Gb) Fibre Channel disks setup in RAID 5. Our applications that run on this SAN do primarily Sequential read and write of large text data files. I'm ...
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159 views

Possible disk IO problem. Help to be sure.

Since some time days ago, one of my servers started crashing. Currently it is crashing almost every day. Sometimes, over once a day. Only a restart can solve. The last time the problem happend, the ...
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2k views

How does Linux handle concurrent disk IO?

When a Linux server is serving many concurrent requests to read many different files, does it: Seek to File_1, read the entire file, then seek to File_2, read the entire file, then seek to File_3, ...
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1answer
607 views

Maximizing throughput of virtual file systems

I've been using a QEMU system to build software. The problem I've been having is that the system seems to suffer from extremely slow disk access. This is not necessarily a problem as it's not really a ...
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182 views

Disk IOs spikes at set times in CentOS

I recently installed Munin on my servers. Now 2 of my machines show big spikes in DiskIO at the same time, everyday at 4am. I run Centos 5.6 (64bit). I've checked my cron logs, and I have no personal ...
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210 views

Does DFS-R actually write 100%+change to a file on the receiving server(s)?

I am analyzing DFS-R on Windows 2003 R2 and have come across a horrendous thing. It appears that when you append a small amount of data to a large (existing) file, the write cost on the server for ...
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1k views

Monitorig ZFS io with Zabbix [closed]

I need to monitor per-zpool IO stats (number of reads, number of writes, size of reads, size of writes) with Zabbix. Is there a script for that? kstat provides only agregate data (all zpools summed ...
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896 views

iotop for Linux kernel 2.6.18

So it has to come to my attention that iotop isn't availalbe for 2.6.18 since it's less than 2.6.20 and requires Python 2.6+. I've done some research and came across this article: ...
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259 views

IO Speed virtual image vs Physical?

I am planning on building a Continuous Integration Server (the existing one is too slow). My plan is to run multiple OSes for our application testing on KVM. The structure will be a single physical ...
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7k views

kernel: scsi 0:0:0:0: rejecting I/O to dead device

Yesterday, OSSEC sent me an alerting email: Jul 29 21:25:16 SVR4149 kernel: end_request: I/O error, dev sda, sector 334634969 Jul 29 21:25:16 SVR4149 kernel: sd 0:0:0:0: SCSI error: return code = ...