Server Fault Stack Exchange
Server Fault Stack Exchange

Questions tagged [io]

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

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

401 questions
2
votes
2 answers

What are front merges in I/O scheduling and how can I tune this parameter?

My Linux uses the Deadline algorithm for I/O scheduling. One of the parameters is the front_merges parameter under /sys/block/sda/queue/iosched/front_merges. By default it is set to 1, which means front merges are likely to occur. One can set it to…
Ely
  • 150
  • 1
  • 9
2
votes
2 answers

No Space left on device after Jenkins installation

Is there any reason i would get a 'No space left on device" error on mkdir. I have confirmed that i have enough space left. around 68% is free. and also i have 1% iNodes consumed. This is CentOS 7 with SELinux disabled. Following is the out of df…
Saad Masood
  • 179
  • 3
  • 10
2
votes
0 answers

Benchmarking for DISK I/O Writes Per Second - ElasticSearch and MySQL

During working on our project we needed to decide should we use "ElasticSearch" or "MySQL" to record the audit/trail logs of the system. Searching speed is not an issue here, we needed to see the disk I/O performance for both platforms. I had no…
Arfeen
  • 121
  • 4
2
votes
0 answers

"Nosy Neighbor" and the CFQ scheduler

I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem. I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all processes(VMs) get fair slices of storage time? If so,…
BlackBeret
  • 123
  • 2
  • 10
2
votes
0 answers

__ticket_spinlock high cpu

We are having a strange problem on our Ubuntu 10.04 KVM infrastructure, where periodically, one of two vm webservers freaks out, with persistently high load, even if we restart the applications. (the only thing using any significant system resources…
righdforsa
  • 283
  • 4
  • 13
2
votes
1 answer

server hangs randomly without log entries

My physical server hangs randomly and I do not get any log entries during that time. So I let a script run: while true; do date >>/tmp/dates; sleep 1; done & disown After some minutes the file /tmp/dates has "holes". Sometimes the dates are…
Thorsten Staerk
  • 387
  • 2
  • 11
2
votes
1 answer

report per-process IO stats with pidstat or sar

I'm trying to track io usage of a few "suspect" processes over time. Ideally would like to make those stats available via munin, or push directly to graphite. However, as a starting point it would be great to be able to track this usage over time in…
Yoav Aner
  • 561
  • 2
  • 6
  • 13
2
votes
0 answers

Visualizing IO other then seekwatcher

Is there any other programs that can generate visuals/graphs/diagrams (movie and pictures) to visualize IO across a full device other then seekwatcher? NOTE: seekwatcher generates visuals(pic/movie) from output traces generated by blktrace. it uses…
kossboss
  • 21
  • 1
2
votes
2 answers

Simulate database I/O behaviour

I'm investigating some performance issue and I need a tool that can mock the same I/O behavior that a typical RDBMS is usually creating. I don't want to install a full blown RDBMS and mess around with configuration just in order to test this…
ApriOri
  • 325
  • 1
  • 10
2
votes
0 answers

Reason for high CPU time when executing fio

After weeks of troubleshooting some performance issues I have on my VPS running Ubuntu 12.04 LTS, I am getting closer to the conclusion that the problem is related to IO. When I have a considerable number of files that need to be access, the CPU…
jbx
  • 93
  • 1
  • 10
2
votes
2 answers

VMWare ESXi: to extend a partition or create a new drive?

Is it better to extend an existing partition or to create a new drive in a VMWare ESXi virtual machine? I'll be using LVM to put the drive in an existing volume group on my VM and to extend a SAN mount point. Which would be better to do and why?
에이바
  • 642
  • 5
  • 11
  • 34
2
votes
3 answers

Detect file update from modification time

Is there a way to see how often a file is being updated? I mean I need to see if the modification time of a file is updated in a dynamic way (same as tail shows if the file is updated in a dynamic way). I can not use e.g. tail since the contents of…
Jim
  • 335
  • 2
  • 4
  • 8
2
votes
1 answer

Poor guest I/O performance KVM Ubuntu 12.04

I have a guest VM running inside a 12.04 Ubuntu host. VM was created using the vmbuilder python script. On the host the phoronix-test-suite "aio-stress" gives a performance speed of >1600MB/s Random Write throughput. The VM (also running 12.04)…
James Smith
  • 21
  • 1
  • 4
2
votes
3 answers

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 disabled 200 MB/s read throughput 30 MB/s write…
Jamona Mican
  • 133
  • 1
  • 6
2
votes
1 answer

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…
Rasmus
  • 53
  • 1
  • 8
1 2 3
…
26 27