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

learn more… | top users | synonyms

0
votes
1answer
14 views

Bytes read / written SNMP value differs from iostat

I am trying to monitor my server over SNMP and UCD-DISKIO-MIB::diskIONRead.1 gives me 1344574464 while iostat reports 9701669 kB_read. Why the discrepancy? I don't have to mention that I am monitoring ...
1
vote
0answers
10 views

LXC (proxmox) JBD high (100%) IO utilisation

We have a dedicated server running a number of smaller guest VMs containing for example, HTTP server, MySQL and some real-time applications. However we find that JBD inside the guests are often ...
0
votes
0answers
14 views

Ubuntu hangs while running make test in IO Socket ssl

Hello I am running ubuntu 14.04 and perl version 5.23.9 (compiled) When I try to build the IO::Socket::SSL module , the machine always freezes. So I installed the module manually. Download from ...
-1
votes
0answers
20 views

Proxmox give more Hdd speed

I have a cpanel in a Proxmox Guest (only being used for webmail), how can I give more IO speed to it? Some times it gets so slow that webmail gets unavailable, and I check disk IO on proxmox graphics ...
-3
votes
1answer
32 views

Serve 200 without reading the request

I have a system where Server receives large files from clients Files are unused and deleted immediately Clients cannot be updated to stop sending files There are a known number of clients (required ...
4
votes
2answers
53 views

Massive performance degradation on sustained sequential write

I'm in the process of migrating data into LUKS partitions. Now that the operating system drive is running off LUKS, I tried to start migrating the data drives. Then the server stopped responding. ...
1
vote
0answers
20 views

Gentoo virt-manager IO throttling

I have a problem with virt-manager (or qemu/libvirt) installed on gentoo. Here is My virt-manager installed on Debian Jessie: There I have IO throttling but not on my Gentoo: I tried to search ...
1
vote
1answer
28 views

Why does SSHFS I/O latency test much faster than local RAID & NFS?

SSHFS tests for server I/O latency using dd returns very surprising results, so much so that I'm worried this might be some problem either with the test method or configuration. Test 1 on local RAID ...
0
votes
1answer
15 views

How to keep md-raid from blocking IO?

I run a server with md-raid (software) level 1 (2 HDDs mirroring) and several different applications run on it. The problem arises when file-intensive jobs (e.g. extracting large archives) run while ...
0
votes
1answer
20 views

Improving I/O rates for EBS snapshot backed volumes

I'm working with a system that takes a set of 42 rotating daily EBS snapshots of each of its numerous (40) volumes for disaster recovery purposes. EBS volumes are aggregated into a RAID volume. A set ...
1
vote
1answer
33 views

How can I determine which files have high I/O in Windows?

In trying to reduce the storage bottleneck on a Windows server (2008 R2) I need to find the files that have the highest I/O over a long period of time (aka 'hot' files) so I can move those to SSD ...
1
vote
2answers
47 views

Disk IO Rate: What causes it and what does it mean to me?

I just got a mail from Linode saying that my account "has exceeded the notification threshold (1000) for disk io rate by averaging 1017.36 for the last 2 hours. " My question is just out of curious: ...
2
votes
1answer
51 views

Filesystem Performance for LUKS Encrypted Volumes?

As you can format a LUKS volume with any filesystem you want, are certain filesystems better-suited to IO performance against an encrypted filesystem? Specifically, I'm wondering about a loop device ...
1
vote
2answers
75 views

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 ...
0
votes
1answer
38 views

Check If I/O causing high load average

I wants to understand how to measure if I/O is causing load average high and how to calculate optimal and critical I/O value. Because sometime there is a load spike on my server but other ...
1
vote
0answers
75 views

How I can reduce disk IO in MySQL 5.6.26?

I was using MySQL version 5.1.52 for my application but recently I have updated it to 5.6.26, but now I am facing very high disk IO. Following are system configuration: OS : Linux 2.6.39.4 RAM : ...
3
votes
2answers
178 views

Acceptable I/O speeds for 6 x 250GB SSDs in RAID 10

I'm running CentOS 7 (XFS filesystem) on a dell server with a PERC H700 raid controller. Inside this server I have 6 x Samsung 850 Evo 250GB SSDs (yes they are consumer drives however, this is a home ...
1
vote
0answers
121 views

KVM bad IO sync performance in Linux guest

I'm setting up virtualized Ubuntu 15.10 guest inside Ubuntu 15.04 server using libvirt and KVM. Storage in host system: # mount | grep ext4 /dev/sda1 on / type ext4 ...
0
votes
0answers
45 views

How to find the bottleneck for slow rsync

I want to find the bottleneck for a slow rsync. I see these parts (on byte flow order): IO on source CPU on source Network CPU on destination IO on destination How can I debug this?
0
votes
0answers
28 views

collectl vs strace - reported block io read/write size

I've got an xfs mount with standard settings (it's an AWS host): [root@host ~]# xfs_info /dev/xvda1 meta-data=/dev/xvda1 isize=256 agcount=4, agsize=524224 blks = ...
1
vote
0answers
15 views

Long Response Times for Reads via FCoE

We're getting some intriguing performance with our new FCoE environment, and I was hoping that people could let me know if what we're seeing is expected behaviour. Our switching environment consists ...
0
votes
0answers
73 views

How can I debug: iostat shows 100 util but there's 0 read or write in iotop

The server is an AWS EC2 instance. Ubuntu 14.04.2 LTS. I have an EBS (xvdf is the device name) mounted to the instance. And this is the problem drive. From iostat I see that drive is 100% utilized ...
1
vote
1answer
50 views

How to check what is causing performance issue

[Edit] This question is different than what is suggested by the moderator, I am trying to find out what could have caused the API to become slow because of the few lines of codes. I am not trying to ...
0
votes
1answer
40 views

How to ensure that I/O requests have returned to a normal rate?

On Amazon Web Services I am using a t2.small EC2 instance as a VPS serving a few websites on a LAMP (PHP) stack. I was just hit with a bill which almost triples my usual bill. I see that my I/O ...
0
votes
0answers
131 views

Starting PHP session sometimes take very long time

Sometime ago we have came upon interesting problem. Sometime (not everytime, lets pretend nearly each 100-200 hit) session_start() takes very long time. Up to 60 seconds. (longest one was 63, ...
1
vote
1answer
32 views

How many milliseconds of await is considered to be high? [closed]

How many milliseconds of await is considered to be high? i have 800ms and 600ms iostat -x avg-cpu: %user %nice %system %iowait %steal %idle 1.28 0.00 0.22 0.90 0.00 ...
0
votes
1answer
16 views

Get NewRelic to respect ionice'd processes

On our web server, we perform an incremental backup of our files every 4 hours using rsnapshot. To perform the actual copying of files, I've configured it to use a custom script, cp-nice that has the ...
1
vote
2answers
56 views

Most side effect-free way to archive a large file while it is being modified

I am looking after an application that generates a large amount of data in a log file (about 5G a day) on a Red Hat server. This process runs for 24 hours during the week, so there is no point in the ...
1
vote
0answers
94 views

Redis parent process smashing disk despite appendfsync = no

We are seeing loads of IO from redis-server despite our save operations being set to occur once every 15 minutes only. The workload is a "full page cache"; we store blobs of compressed HTML. The HTML ...
0
votes
1answer
54 views

Ubuntu 12.04 high io by root process

Ubuntu server 12.04. Installed on hdd disk. There is postgresql database on server runing on other ssd disk. The problem is in high io by some root process on hdd disk. iotop shows 2 processes with ...
-1
votes
1answer
64 views

Ubuntu CPU I/O Rate Spike

Getting really crazy spikes today on a Ubuntu server for CPU / IO. CPU Chart is showing as much as 210% CPU usage - no idea how that is possible. IO has gone as high as 11912. (Usually well under ...
0
votes
1answer
335 views

Finding correct IOPS to set limit with ESXi 5.5u2 and vSphere

We're running an ESXi 5.5u2 hypervisor that has a mirror of 2 15k SAS drives with a couple of VMs inside and we noticed some services become briefly unreachable if another VM is using all the IO. So ...
0
votes
0answers
94 views

DRBD high iowait every 65 seconds

I have a peculiar problem: simple INSERT queries to MySQL slow down and appear in my slow q logs every 65 seconds exactly. My stack looks like: mysql56u (IUS) on CentOS over ext4 over drbd over ...
1
vote
1answer
41 views

Sustained io testing linux

I wish to hammer the io of some disks for an extended period of time and become aware whenever I can't read from a block (or some other symptom letting me know of an issue with backend storage). There ...
0
votes
1answer
30 views

Is “'Light-Speed' Disk Access” really a thing? [closed]

I just saw an advert for Hyve hosting on You Tube. One statement made me curious, they said they offer "'Light-Speed' Disk Access": Is this just a fancy way of saying they have optical technology, ...
0
votes
1answer
80 views

High on %wa from top command, is there any way to constrain it?

Here's my last top info before it stucks: top - 18:26:10 up 238 days, 5:43, 3 users, load average: 1782.01, 1824.47, 1680.36 Tasks: 1938 total, 1 running, 1937 sleeping, 0 stopped, 0 zombie ...
0
votes
2answers
279 views

Does Linux, Apache HTTPD or PHP cache frequently / recently accessed files?

Let's say we have a simple index.php file that goes: <?php inclde('file1.php'); inclde('file2.php'); inclde('file3.php'); Presumably, this will ultimately result in three additional ...
0
votes
3answers
334 views

I/O and RAM limitations are important for Hadoop performance. But is disk speed related to I/O?

Hortonworks says this: "Most often performance of a Hadoop cluster will not be constrained by disk speed – I/O and RAM limitations will be more important." * How is disk speed not related to I/O ...
13
votes
3answers
2k views

Virtual machines and I/O heavy workload, is it ever sane?

I have seen on numerous virtualization services (Azure) and products (vmware,kvm,hyperv) I/O and system stalls under heavy I/O workload. My questions are: Is it ever sane to use a Virtualized ...
1
vote
2answers
454 views

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 ...
0
votes
0answers
145 views

mdadm and LVM high load and IOwait

I've got a new CentOS 6.6 server with 2 HDD with mdadm & LVM. As I've used the CentOS install CD I assume everything should be aligned properly. I've just written a KVM image to a LVM LV using dd ...
0
votes
1answer
212 views

What it means when Linux has no I/O scheduler

I have some virtual machines running Ubuntu cloud-based image 14.04-1 LTS version. I wanted to see the IO performance of different IO schedulers on the VM so I went to ...
0
votes
0answers
272 views

PHP-FPM Stuck & High IO

Actually on my mutual hosting server I'm using PHP 5.6.3 with one pool. Sometimes, my php-fpm process is stuck with 50% of WA and I can't kill it, I can't even restart my VM. I'm using 245MB/3968MB, ...
0
votes
1answer
75 views

ubuntu kvm disk io slowdown after some tyme

Host system: Ubuntu Server x64 12.04 mdadm raid 1 (/dev/sda /dev/sdb) no lvm dd bs=1M count=256 if=/dev/zero of=filename conv=fdatasync avarage ~ 40 MB/s NCQ on disks is disabled WriteCache is ...
0
votes
0answers
105 views

MySQL slow file I/O

I got a little issue with MySQL having slow file IO. When benchmarking 1k blocks (I did them on purpose that small for worst-case) I get an hdd speed of about 2MB/s. When looking at iotop while ...
0
votes
2answers
55 views

how to find the highest IO consumer on a disk? [closed]

Can some one help to find highest IO consumer on each individual disks? i.e Which process consumes the most IO on /dev/sda, the highest IO consumer on /dev/sdb etc.
1
vote
0answers
54 views

File IO being slow

I've rented this root server with a RAID1 mdadm software raid setup. Using dd to benchmark the file IO speed it achieves 230MB/s write (default blocksize). Certain tasks such as mysql are way slower, ...
0
votes
2answers
101 views

how to check if a process with heavy io usage is running properly

I am now managing a computer cluster for scientific computing. Some processes in the cluster need heavy io usage. Now I find such a process: Its state changes rapidly between DOWN and RUN and its ...
1
vote
1answer
67 views

What is the purpose of a ramdisk when fadvise exists?

My understanding is that fadvise will tell the system that the indicated files should be stored in the file system cache (RAM). What is the purpose of mounting a directory in a ramdisk when you can ...
4
votes
2answers
377 views

99% disk IO spikes with Percona

So we have a server that has seemingly random spikes in disk I/O, going up to 99.x% at random times and for no obvious reason, staying high for a while, and then going back down. This didn't use to be ...