Questions tagged [io]
IO (or I/O) is an abbreviation for input/output, most commonly referring to disk input/output.
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Are there any industry standards for network timeout or / IO timeout etc? [closed]
I was reading this article about microbursts: https://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/white-paper-c11-733020.html
which can also cause traffic drops.
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What does iodepth in fio tests really mean? Is it the queue depth?
I understand queue depth which is the number of outstanding I/O requests that the storage controller can handle (https://www.tomshardware.com/reviews/ssd-gaming-performance,2991-3.html) i.e., this is ...
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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 ...
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what is the relation between block size and IO?
I have been reading about disk recently which led me to 3 different doubts. And I am not able to link them together. Three different terms I am confused with are block size, IO and Performance.
I ...
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How can I prevent high-volume filesystem writes from ovewhelming memory on my Linux system?
In several contexts, I've seen a behavior on Linux systems in which large volumes of filesystem write operations (e.g., many gigabytes of writes, very quickly) will overwhelm memory, apparently ...
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Give read operations priority over write
I'm working on a system where I have a program that outputs high quality videos for a tv connected to an HDMI (raw 1080p data for instance) and I'm having an issue that when I copy some files to my ...
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Should sector-unaligned HDD writes be slower than sector-aligned writes?
Background: I'm planning to use ZFS and I need to find the correct ashift parameter for my harddrive, which should be log2(sector_size), e.g. 9 for 512 byte sectors.
My harddrive reports a physical ...
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Mariadb 10.3 high disk write rates
With the help of some other fine people here, I have found the high loads we have been experiencing lately are related to mysqld high disk write rate seen in iotop. With a load average now 3-6 where ...
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Linux: how can I determine if an application is doing sequential or random disk I/O?
Everyone knows that databases tend to do lots of small random I/O while big data things like Kafka tend to do large sequential I/O, but if I'm approaching this as a sysadmin without making assumptions,...
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How to disable search body in dovecot?
We run mail server of 30k e-mail accounts (Maildir) with Dovecot imap server. We suffer from high IO load, especially when a user starts to search large IMAP folders. Is any way of preventing search ...
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Does ESX 5.X cache guest IO?
I am trying to find out if guest can see successful disk flush operation, but the host doesn't actually flush it to disk?
How does ESXi work with guest I/O? Are they cached by ESXi before being ...
- 111
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Determine what's causing high disk I/O
I have a problem with my VPS and disk I/O. My server is running nginx + PHP-FPM + APC. The database is located on another dedicated VPS. I have several WordPress MU sites living on the web server. The ...
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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 ...
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Disk/Controller Performance Comparison
Since 2012 Iam using the HP Proliant Dl385 G7 with Smart Array P410i.
2xAMD Opteron 2.4GHz, 24 Cores
System Disk C: 2xSAS 15k in RAID1
Some time ago I purchased a new HP Proliant Dl380 G9 with Smart ...
- 2,172
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file system corrupt in a virtual machine
I have a virtual machine hosted by vmware esxi. It has been started for over 80 days. And about ten days ago, its file system got corrupted. Although I can use fsck to fix this file system, I am ...
CommunityBot
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Troubleshooting `Buffer I/O error` on software-raid/md-device
I've got a RAID-5 mdadm array that reliably causes Buffer I/O error on dev md0, logical block 1598030208, async page read to be written do dmesg when reading that block. Of course, the read also ...
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VMWare - VM won't start - 5 (Input/output error) - failed drive
Basics:
Server with 4 drives, 2 solid state. One of the solid state drives appears to have failed. Running VMWare 5.0
We tried to distribute the VMs over several disks and using RAID, but I'm not ...
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Does ionice has any effect on NFS client?
I need to remove millions of directories recursively on a NFS share and to avoid any performance issues, I ran the command with:
ionice -c 3 -t find /dir -type f -exec rm {};
which will delete all ...
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Linux - How can I see what's waiting for disk IO
I have a server that has a really high load. Nothing is jumping out at me in terms of CPU usage, and it's not swapping.
I think it's cause some processes are waiting for disk IO, and I want to see ...
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How to determine if I/O is slow for server
I have used I/O stat to check whether my server's I/O is slow or not. The % util is high but so is the read/sec - write/sec. Can anyone help ?
Following is the output of iostat -mx command
Linux 2.6....
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Centos7 - Buffer I/O error on dev sda, logical block xxxxxxxxx, lost async page write
I have a webserver that have the content in HP MSA2040 Storage (10 tb total storage).
I keep getting error like below
Jul 31 19:06:24 xxxxxxxx*** kernel: blk_update_request: I/O error, dev sda, ...
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How to check why a write failed? [closed]
If I was to debug a service on a machine and I determined that a write was failing, how could I check why the write failed?
I know the system call in C will return -1 and then we can check what ...
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RAID6 resync with fast writes but slow reads
I'm using Debian Jessie.
# uname -a
Linux host 4.9.0-0.bpo.3-amd64 #1 SMP Debian 4.9.30-2+deb9u5~bpo8+1 (2017-09-28) x86_64 GNU/Linux
And have setup a RAID6.
# cat /proc/mdstat
Personalities : [...
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Google compute: Why persistent ssd disks are slower than persistent standard disks?
I ran several IO benchmarks and I cannot understand how pd-ssd offers a worse IO throughtput than pd-standard.
In my tests I boot a VM with a bootable disk pd-ssd of 30 or 250GB, and I still get ...
google-cloud-platform
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KVM/QUEMU guest slow disk performance
I'm really confused of QEMU/KVM behavior. I have a server - about 100GB RAM, 2 CPU - 6 core + HT, and three HDDs - one for root, and two for BTRFS-mirror for virtual machines (HGST HDN724030ALE640 if ...
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Poor disk IO on Redhat VM on Hyper-V 2012 R2
We recently migrated a RedHat 5.11 virtual machine from an alternative provider (VMWare) to ourselves (HyperV).
The machine boots and is online etc, but the IO sucks compared to pre-migration...
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How to determine a QEMU virtual machine is idle?
I am working on a KVM-QEMU virtual machine.Currently I want to find out whether a program (e.g., MySql) running inside the virtual machine is idle (i.e., not busy processing requests).
I want to get ...
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Could the amount of files in a windows directory impact the time it takes to copy new files into it?
I have a export process that dumps new files into a folder on my Windows 7 PC each day (about 1-2K). This directory is now unusably slow to navigate through Windows Explorer with millions of files in ...
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What does the nomerge mean in Linux system?
We can see some parameters by issuing "iostat -x -d", the rrqm/s and wrqm/s stand for the merge for I/O request per second. And there is a kernel parameter controlling the I/O merge:
/sys/class/block/...
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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:
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Do I need to create multiple filesystems on a virtual server to increase I/O performance?
I want to install Oracle on a virtual server. I don't really know the technology behind, my company just gave me a virtual server with multiple (virtual) disks.
I have the possibility to divide those ...
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A lot more write then read IO [closed]
As shown in the picture above we are having a lot more writes then reads on our appserver. Cache is enabled and the Framework is running with PHP/Symofony and using HTTP Cache.
Is this I/O behavior ...
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Why is io scheduler not merging requests?
After some time (or amount of data written) after server reboot the write speed drops to less than 1 MB/s. This is regardless of which filesystem (also raw partition) and regardless of HDD (HW RAID) ...
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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.
...
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Does having a good or bad filesystem inside a Virtual machine really matters?
I want to understand how the IO is sent to hard disk blocks from a virtual machine.
Does having a XFS or ext3 or ext4 etc. really matters inside a virtual machine, or it is just depended on the file ...
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Ramdisk vs Build-In IO Caching on Windows
I'm trying to understand the built-in IO cache on Windows. If an application writes to a file, and then reads/writes it multiple subsequent times, it seems that the IO cache should allow this to ...
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Evaluating the CPU I/O wait on Linux
Doing a top to check the io wait, I get these figures:
Cpu(s): 6.7%us, 1.4%sy, 1.2%ni, 85.5%id, 5.0%wa, 0.0%hi, 0.3%si, 0.0%st
Looking at these figures (%us ~= %wa), do they mean that:
there ...
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AWS EC2 snapshot reaches IOPS limit occasionally
For an EC2 server I have running I am creating a snapshot of the EBS every night. The EBS has 500GB of space and 1500 / 3000 IOPS. On some days past week the snapshot creating process reached it ...
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How can I monitor disk IO load on a Windows 2008 server?
We are running multiple processes on our servers, which are mostly CPU intensive, but also use the local HDDs for reading the data. I can trivially look at the CPU load and memory usage in TaskManager ...
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Linux software RAID becomes unresponsive after removing a disk from server
I am running a CentOS 7 machine (standard kernel: 3.10.0-327.36.3.el7.x86_64) with a software RAID-10 over 16x 1 TB SSDs (to be more precise, there are two RAID arrays on the disks; one of the arrays ...
CommunityBot
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Use deadline I/O Scheduler on BusyBox v1.16.1
Does anyone know how to add / make available the deadline I/O schedulers on BusyBox v1.16.1 ? The only two I see when I run "cat/sys/block/sda/queue/scheduler" is as follows:
[noop] cfq
My ...
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MySQL extremely slow on very simple SELECT queries
We have a simple web application running on a virtual machine that saves its data in a MySQL 5.5 database with the InnoDB engine. Everything worked fine for around three years, but suddenly it became ...
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Tuning sequential disk reads for performance
I am reading a large file sequentially from the disk and trying to understand the iostat output while the reading is taking place.
Size of the file : 10 GB
Read Buffer : 4 KB
Read ahead (/sys/block/...
CommunityBot
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what is snmp mib for getting NFS IO counters?
I can get local disk I/O requests and read/write bytes using the following snmp MIB:
SNMP table: UCD-DISKIO-MIB::diskIOTable
diskIOIndex diskIODevice diskIONRead diskIONWritten diskIOReads ...
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Why is my btrfs/dm-crypt RAID1 setup so slow?
I have a system that's set up with a four-disk RAID1 array based on btrfs. Two disks are 1TB traditional HDDs, and the other two are 128GB SSDs. Most of each disk is filled up with a LUKS container. ...
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I/O high on DRBD disk drbd10 on stacked site
We have 4 Redhat Boxes Dell PowerEdge R630 (say a,b,c,d) having the following OS/packages.
RedHat EL 6.5 MySql Enterprise 5.6 DRBD 8.4 Corosync 1.4.7
We have setup 4-way stacked drbd resources as ...
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How efficient is the tac command on large files
The taccommand (catreversed) can be used to read a file backwards, just like cat reads it rom the beginning. I wonder, how efficient this is. Does it have to read the whole file from the beginning and ...
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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 ...
CommunityBot
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Input/output error reading USB backup drive on CentOS 6.4
I'm suddenly seeing some strange behaviour on our USB backup drive that doesn't make sense to me:
(2013-10-21 14:58:23 [root@newdc /]$ cd /mnt/backup/
(2013-10-21 14:59:03 [root@newdc backup]$ ls -la
...
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Poor Write I/O Performance on HP ML110 G9 Server With ESXi 6.0U2
hi everyone i need a little bit of help since i cant find a solution,
i have a HP ML110 G9 Server with:
8gb Ram
2 HDD of 2tb Each one and one SSD of 250 GB
i have installed ESXi 6.0u2 HP Customized....
