IO (or I/O) is an abbreviation for input/output.

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Issues with Server 2012 using DFSR running on Hyper-V 2012

We have a number of Server 2012 systems, all of which run virtualised on Hyper-V 2012 server. We are having problems with two such virtual instances, both of which are used as file servers, whereby ...
3
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1answer
2k views

Strange high CPU I/O wait on postgresql server

I'm really struggling with a performance issue currently, where all my database queries takes up to a 1000 times more than normally, when my database server is under "heavy" load. I have a server ...
5
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1answer
2k views

High I/O latency with software RAID, LUKS encrypted and LVM partitioned KVM setup

I found out a performance problems with a Mumble server, which I described in a previous question are caused by an I/O latency problem of unknown origin. As I have no idea what is causing this and how ...
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3answers
3k views

iostat shows 100% utilization - what can be done to improve performance?

I have dedicated web server with CentOS. Recently, I get very high server load, probably caused due to IO bottleneck. iostat -mx 3 shows: avg-cpu: %user %nice %system %iowait %steal %idle ...
0
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2answers
154 views

Does php function move_uploaded_file() cause disk io?

The /tmp dir and the destination dirs are on the same file system. If its handling large files (over 1GB), does this create any overhead in term of disk io? Would it be better to simply have php put ...
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0answers
48 views

Chrooted from LiveCD: Bad IO performace

my Ubuntu Server installation is broken, so I grabbed a Ubuntu Desktop CD, mounted my Ubuntu installtion on my hard disk and chrooted into it. But now my IO performance is really bad: # time dd ...
0
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1answer
338 views

Proxmox VE Logical Volume in RAW format?

I added a Volume group in Proxmox VE as Storage for KVM VMs. A new Logical Volume will be created for each VM, but in Proxmox VE under The Defined Storage which shows list of created Logical Volumes I ...
1
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1answer
408 views

high disk usage = io-bound on an apache + postgresql web server?

I have a server running apache, postgresql, and a lot of sites, and my graphs from my hosting provider indicate basically constant disk thrashing. 10k/s disk usage. This seems like a bad idea, but I'm ...
0
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1answer
354 views

I/O limits in FreeBSD

I am searching for a method to implement per Jail I/O limits in FreeBSD, as linux have from a long time now. During my research I stumbled upon: http://info.iet.unipi.it/~luigi/geom_sched/ My ...
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3answers
2k views

RAID10 without write-back cache = horrible write performance?

I have just provisioned a dedicated server on singlehop. I'm running it through some tests to know what to expect performance-wise. On the I/O side (with 4 1TB disks in RAID 10) I get: write-cache ...
2
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2answers
1k views

How iostat figures out to take CPU idle time to consider as %idle or %iowait?

I was going through iostat man page. According to it, %iowait Show the percentage of time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request. %idle ...
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2answers
486 views

Testing a production hard hard / debugging high I/O Load

I've been getting a lot of high load lately on this server more so then it should for what little is on this system. Seems like just the simplest stuff using the disk like a YUM update will spike the ...
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3answers
212 views

How to arrange 2 SSD with 2 SATA? [closed]

I like to have best io performance as well as good capaciyy and reliability out of a server that hosts a busy forum, which involves loads of static files download. I am wondering what is the best plan ...
3
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0answers
44 views

How can I measure disk cache churn on Linux? [duplicate]

Possible Duplicate: Is there a way to get Cache Hit/Miss ratios for block devices in Linux? I have a file server which serves out large (25GB-1TB+) files over the network from local ...
0
votes
1answer
515 views

How to check which processes are deleting files without using inotify or auditd? [closed]

I'm trying to figure out which processes are deleting files from a specific directory on my CentOS server. I looked at inotify, but all this does is to tell me how many file deletions are occurring; ...
2
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2answers
325 views

How to figure out which processes are deleting files from a specific directory?

I'm trying to figure out which processes are deleting files from a specific directory, so I want to set up and run auditd on my system. I've set up the following rule in audit.rules: -w S unlink -S ...
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1answer
407 views

What buffer size should I use to maximize disk I/O bandwidth? (16Kb, 32Kb, 64Kb, etc.) [closed]

I am trying to write a file as fast as I can through a buffered FileChannel similar to a BufferedOutputStream. I am wondering what is the optimum chunk of data I should use per write call to maximize ...
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0answers
502 views

I/O error on non-existent device?

Getting the following in /var/log/messages: Sep 17 10:38:53 server1 kernel: end_request: I/O error, dev sde, sector 0 Sep 17 10:38:53 server1 kernel: end_request: I/O error, dev sde, sector 63 Sep 17 ...
4
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3answers
1k views

Linux utility to record IO statistics (random/sequential, block sizes, read/write ratio)

As part of provisioning our new server (see other SF) I'd like to find out the following: ratio of random to sequential reads & writes amount of data read & written at a time (pref in ...
2
votes
1answer
991 views

Debian: nginx using an extreme amount of disk I/O

We're currently haveing an issue with one of our nginx servers. It's using an extreme amount of disk I/O. It's the / (root - cciss/c0d0) partition that's being abused. See picture of iotop here: ...
0
votes
1answer
134 views

replacement drive cage for power edge R710

Hi I'm performance tuning a DB server its a Dell R710 there is a very significant I/O bottleneck. Unfortunately the server was purchased with the 6 x 3.5 inch sata configuration which doesn't give me ...
2
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1answer
416 views

Limit linux buffer usage by process

We have a production server running different process which take advantage of existing linux buffers to improve their performance, such as a mysql server. This server has exhaustive IO load. On this ...
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1answer
67 views

Partitioning disk I/O on linux

I have a server that runs two different workloads: heavy, linear write (stores all network traffic as pcaps); and a transactional DB workload where IDS alerts are written to (frequent inserts) and ...
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2answers
3k views

Very high load, apparently caused by pdflush

I have a server that's running CentOS 5, and it will periodically (a couple of times a day) have enormous spikes in load, and the whole server will grind to a halt. After a couple of minutes, the load ...
2
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3answers
308 views

Analysing Disk IO Traffic

I am running a web server (Ubuntu 11.04) that exhibits unexpected high write traffic. When the server is not supposed to write at all, the amount of write traffic is comparable to the read traffic. ...
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2answers
1k views

Can fragmented MySQL innodb tables cause I/O issues? “task hung for 120 seconds” crashes?

Large innodb databases with load spikes seem to be causing random crashes with "task hung for 120 seconds" in the console. There are no logs being written to the system during these crashes. The ...
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6answers
1k views

Linux I/O bottleneck with data-movers

I have a 24 core machine with 94.6GiB RAM running Ubuntu server 10.04. The box is experiencing high %iowait, unlike another server we have (4 cores) running the same types and amounts of processes. ...
2
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2answers
706 views

How does I/O performance on Intel E5 procs change with and without QPI

I am in the process of specifying a low-mid range server (which we will purchase multiples of). The application is essentially a software router, so it is very NIC-based I/O intensive. Processor ...
6
votes
1answer
135 views

How to prevent IO Load under Linux for Video serving?

I'm currently serving videos of conferences via Nginx on 3 servers; 4 cores, enough memory (no swap used) and RAID-10 with 8 drives per server. Unfortunately iostat -xd 1 gives me 100% on all 3 ...
0
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1answer
402 views

NFS exports priority on server

I've got a server with several directories shared in exports. One of these exported directories holds home directories, others hold some random data. Is it possible somehow to prioritize i/o coming ...
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3answers
417 views

Extremely High Hard Disk Reading Usage

My VPS configuration is as follows: H.D.D = 25GB RAM = 256MB OS : CentOS 5.5 I received an email from server provider showing that my VPS H.D.D read usage is 137GB in one day. I have installed ...
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1answer
1k views

What are some options for acquiring a free realtime Linux distribution? [closed]

By realtime I mean something that can help with fast network I/O; Low-latency and high-throughput.
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2answers
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Can I run iostat on a Synology?

I have a Synology RS812RP+ which I'm using for a little bit of departmental testing. I've stuffed a bunch of SSD disks in it, and I'm curious about monitoring the disk IO. iostat doesn't come ...
2
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2answers
57 views

Fastest security check of file tree on NFS

I am currently experiencing very bad performance using the following on an NFS network folder: time find . | while read f; do test -L "$f" && f=$(readlink -m $f); grp="$(stat -c %G $f)"; ...
2
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0answers
280 views

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 ...
3
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1answer
771 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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2answers
464 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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2answers
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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0answers
502 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 ...
6
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2answers
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
618 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 ...
0
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1answer
825 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, ...
0
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1answer
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 ...
2
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1answer
454 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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3answers
820 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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1answer
57 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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2answers
513 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 ...
2
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1answer
498 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 ...
12
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11answers
7k 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
817 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 ...