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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
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Running a process within a limited amount of resources, in Linux

Is there a way to run a process (e.g. ls, du, find .. etc) within a strictly limited amount of resources (i.e. cpu, memory, I/O) aside from using nice & ionice, as I didn't find them effective enough in my case. I have a production server, that has…
yalu
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Limited I/O Performance in Dell T410

We have a small number of Dell T410 and T710 systems. Each has a Dell SAS 6iR controller with 6 SATAII disks, 1x160GB OS and 5x3TB DATA disks. We have been having disk access speed issues all along, each disk giving little more than 100MB/s…
TomS
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Poor KVM guest IO performances

I've a DOM0 packed with two 3TB hard drives configured as a software RAID1, also sporting 16GB of memory. The DOM0's Linux distro is a CentOS 6.3 and the hypervisor is a libvirt-managed KVM. I'm experiencing performances degradations between the…
Cristiano Paris
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Linux buffer memory always stays at zero

One of my hosted server is a Xen guest running Debian and linux kernel 2.6.32 then 2.6.38. It has been running fine for quite some time (more than a year) but I recently noticed something weird. For a few months, the part of the memory allocated…
Lætitia
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2 answers

Determining cause of high NFS/IO utilization without iotop

I have a server that is doing an NFSv4 export for user's home directories. There are roughly 25 users (mostly developers/analysts) and about 40 servers mounting the home directory export. Performance is miserable, with users often seeing…
Matt
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Quantifying the effects of partition mis-alignment

I'm experiencing some significant performance issues on an NFS server. I've been reading up a bit on partition alignment, and I think I have my partitions mis-aligned. I can't find anything that tells me how to actually quantify the effects of…
Matt
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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 Show the percentage of time that the CPU or CPUs…
pradeepchhetri
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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 drive well in 10LA when it runs well under 1.…
Tiffany Walker
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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 truncate -S ftruncate -a exit,always -k…
Tola Odejayi
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2 answers

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 will go back down and everything returns to…
Dean Harding
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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 innodb tables are fairly large, 20+ gigs in…
Tom G
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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 selection is proving challenging. In comparing the…
HikeOnPast
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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 only thing running on this machine. I has open…
PersonalNexus
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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 caching, io mode default, and LVM logical volumes…
Tader
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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 we'll release. I have been using Amazon Web Services…
rhossi
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