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Questions tagged [swap]

Linux divides its physical RAM (random access memory) into chucks of memory called pages. Swapping is the process whereby a page of memory is copied to the preconfigured space on the hard disk, called swap space, to free up that page of memory. The combined sizes of the physical memory(RAM) and the swap space is the amount of virtual memory available. Linux has two forms of swap space: the swap partition and the swap file.

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FreeBSD swap usage with mysql

For the past few months, on a few different servers with similar FreeBSD versions and specs, I've been experiencing high swap usage with MySQL while seemingly having plenty of free RAM. FreeBSD 11.2-...
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5answers
39k views

Why don't EC2 ubuntu images have swap?

I started a couple servers on EC2 and they don't have swap. Am I doing something wrong or is it that the machines just don't have any?
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4answers
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Best way to disable swap in Linux

I am running a custom compiled 3.18.9 kernel and I am wondering about the best way to disable swap on the system. I also use init if it makes a difference. Is it enough to comment or remove the swap ...
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1answer
1k views

Linux Mint: Python process gets “MemoryError” before swap is even close to fully used

I'm attempting to run a Python script that requires a lot of Virtual Memory. I'm on Linux Mint 17.3 64 bit and Python 2.7. As the Python process grows, I can see (using free -m) the amount of RAM ...
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0answers
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Docker memory swap account broken in ubuntu 14.04.2

I'm using ubuntu 14.04.2 . I saw that recently swap support was broken, maybe with a recent kernel upgrade? On a fresh install: cat /etc/default/grub: GRUB_CMDLINE_LINUX_DEFAULT="cgroup_enable=...
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1answer
35 views

Increasing swap space and removing previous swap space on ubuntu?

I have a virtual machine (hosted online) with 2Gb swap space. free -m total used free shared buffers cached Mem: 1995 438 1557 37 ...
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how to know the right swap size for hadoop Linux machines

we are using many hadoop clusters for now we are using swap size - 16G free -g total used free shared buff/cache available Mem: 125 ...
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1answer
3k views

ATOP: vmcom / vmlim -> SWP is red

in ATOP I'm getting a red alert like this: vmcom 76.3G | vmlim 49.8G This is a value that is attached to the "SWP" (so "SWAP" is meant?)-line. What does this mean and what can I do against it?
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docker rm,exec, rmi commands are in hang state

I am facing the issue with docker since couple of weeks. Some of docker commands like rm, rmi, exec are not working, while, commands like ps, images are working fine. I tried - docker system ...
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0answers
46 views

Squid docker container configuration and swap

I'm currently running 4 squid container on my VPS. The server is a 1 vCore cpu with only 512 mb ram. I don't need a high percentage of hit rate, i don't need cache at all in fact. Starting from the ...
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3answers
24k views

“Lack of free swap space” on Windows Server

I have several Windows Server 2012 Virtual Machines, which are monitored by zabbix 2.4. The zabbix throws "Lack of free swap space" for some VMs, but there are disk and memory free on these machines, ...
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4answers
2k views

Should I turn off swap on AWS EC2?

I'm running a webserver and database server on the same AWS EC2 instance. I know it's a bad idea to have swap for web server, so should I just turn it off? Will it affect the database service (I guess ...
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2answers
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Is swap file required for a Postgres database running on AWS EC2 instance with 122 GB memory?

What is the downside for running a Postgres database without a swap file? This database resides on an AWS EC2 machine with 122 GB memory.
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1answer
49 views

Centos 6.10 Swap File Issue Wrong size

I have Centos 6.10 Server with initial swap of 3.81 GB working ok no issue. I noticed wrong swap today amount of 4kb. I tried removing the partition and recreate entry on fstab and remount but no ...
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2answers
170 views

Is there a way to force a single process to swap most/all of its memory to disk (NON-ROOT)

We are currently analyzing performance of some of our boxes at work and we find that we have boxes that are swapping a lot and things start crawling when that starts to happen cause we are using ...
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1answer
127 views

Make Ubuntu Server use less swap and more actual RAM

I have a server with 128 GB of RAM and a 100 GB hard drive in it. It seems to use pretty much swap instead of using actual RAM when rsyncing disks. I found other questions on Stack Overflow with ...
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1answer
267 views

kswapd process causing high system CPU

I'm troubleshooting some issues with my RHEL 5 server. This is an Oracle DB server which are running for a while now without much issue. Lately I notice that the server load is relatively high due to ...
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3answers
10k views

What is the danger in having a fully used SWAP in an Ubuntu server?

One of my Ubuntu servers' swap partition is full. What are the dangers and/or performance ramifications of this situation?
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3answers
2k views

How can I keep important VMs in memory without disabling swap?

VM Host -> Xenon E5-2440 w/ 48G mem... Everything runs CentOS6.5 (2.6.32-431) I have 4 guest VMs running each w/ 2G of memory. Their disk images are local files. The host machine is also running a ...
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4answers
3k views

Running swap on RAID10 or RAID5?

In follow-up to this previous question (and it's excellent answer), I am curious to know if running swap on a RAID5 might not be better than on a RAID10. My thinking is that you might lose a bit on ...
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4answers
2k views

Can I run an Oracle server without swap?

Official Oracle docs say that for a machine with more than 16GiB of RAM we need to allocate 16GiB of swap. Our servers are RHEL 7 and have 256GiB of RAM. DBAs do not want to see the system swap, so ...
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4answers
11k views

Why disable swap on kubernetes

Since Kubernetes 1.8, it seems I need to disable swap on my nodes (or set --fail-swap-on to false). I cannot find the technical reason why Kubernetes insists on the swap being disabled. Is this for ...
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0answers
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Why is my kernel choosing disk swap over 24G of inactive RAM?

Output below is meminfo from a Proxmox hypervisor. I noticed today that swap usage was 90%. I logged into the box and checked and and it seems there is actually 24G of inactive RAM. A couple minutes ...
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4answers
730 views

Creating swap files faster

I'm using Amazon EC2 and wish to be able to quickly generate large swapfiles (~10+GB) on instance startup. Unfortunately, I/O speed on my instances (c1.xlarge) is slow enough (20 MB/s) that this ...
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3answers
83 views

Missing mdam RAID1 array during scan

I have built a new server (Ubuntu 18.04.1) with 4 HDD. My plan is to use RAID1 overall and came up with this layout after investigation: sda, sdb four primary partitions (all as fd) with sda1/sdb1 ...
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How to create randomly keyed swap with Kickstart

I want to create an encrypted swap partition using Kickstart. Instructions on how to create encrypted swap manually are in the related question How to create a randomly keyed, encrypted swap ...
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2answers
7k views

Avoiding swap on ElastiCache Redis

We have been having ongoing trouble with our ElastiCache Redis instance swapping. Amazon seems to have some crude internal monitoring in place which notices swap usage spikes and simply restarts the ...
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1answer
368 views

Proxmox doesn't recongnize increased swap space

So I tried to increase the swap LV from 8GB to 16GB, but Proxmox web panel doesn't seem to see the change. The LVM increased the space, but Proxmox haven't changed it's panel. Originally lvdisplay ...
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1answer
205 views

swapon & hibernate on power key

I have a laptop & I run Arch Linux. My laptop has a spinning hard drive rather than an SSD, so I hate swap. However, I need one to hibernate, and I want my laptop to hibernate every time power key ...
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2answers
923 views

Could swap use many inodes?

I have got a graph about high inode use of our server's disk but I haven't got any detailed information (like df -i) so I'd like to guess the reason. Operating System: Red Hat Linux Process: PDF ...
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1answer
252 views

rsyslogd uses 435M of swap memory right after restart

I have Centos 7 # cat /etc/centos-release CentOS Linux release 7.3.1611 (Core) fresh rsyslogd # rsyslogd -version rsyslogd 8.36.0, compiled with: enough free memory # free ...
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1answer
36 views

Machine swapping despite there being enough memory

One of our Docker hosts is swapping like hell for no reason - at least, no apparent one (it's a Ubuntu 16.04LTS VM). All Docker containers in summary only use ~4 GB of the 12GB RAM total, but the ...
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4answers
63k views

How do I tell if my Windows server is swapping?

I'm using Process Explorer to monitor my windows server while it reconstructs some data. It's primarily a CPU intensive process, but I want to make sure it's not swapping. How can I tell if it is ...
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1answer
16k views

why is kswapd using high CPU on an idle system?

I have an idle Linux centOS system and yet kswapd is using 100% cpu. All I have running is a single bash session with top running.... I have 32G RAM and yet kswapd is constantly using 100% cpu for ...
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1answer
549 views

mysql swap file crash on freebsd

I have a low memory VPS that mysql and the swap file crash out every morning at exactly 0300. There are no cronjobs on the system that have been configured. The server is a basic LAMP development ...
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0answers
215 views

Swap unused, high memory usage and swappiness at 100

I'm running a server with a number of game servers on it. My memory usage is very high, however there is almost no swap usage in comparison. My swappiness is set to 100 total ...
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10answers
23k views

Linux: how to explicitly unswap everything possible?

I've launched something that took lots of memory and now everything lags a lot. I guess all applications' memory has gone to swap in order to free some space for the memory-intensive process, and now ...
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1answer
149 views

JVM heap is being swapped causing GC go haywire - Tomcat

Info: # of VMs= 4, each with an instance of Tomcat 8.5.* in cluster Apps = 5 war applications- 2 UI applications and 3 Webservices. Java Version = java 1.8.* Configuratin = 2 LTMS and 2 Apache ...
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0answers
148 views

Cannot mount swap partition at boot on Amazon Linux 2

I am trying to mount swap partition in etc/fstab on Amazon Linux 2, but it doesn't work on the boot-up process. here the steps I have followed: create swap file: dd if=/dev/zero of=/swapfile bs=1024 ...
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0answers
2k views

Linux swap partition not mounted by systemd on boot after dist-upgrade

Recently, I performed a dist-upgrade from Debian Wheezy to Jessie. The upgrade was performed without any error but after the upgrade the swap partition was no longer mounted/activated. The mentioned ...
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2answers
520 views

High swap usage on CentOS server with plenty of spare RAM

We have a fleet of web hosting servers all running the exact same software & hardware with similar load. One of our server gets very high load that leads to it locking up for brief periods of ...
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2answers
967 views

Swap with a huge amount of ram available

I have an old, legacy server with an odd problem with swap. Linux version: Red Hat Enterprise Linux Server release 5.6 (Tikanga) Kernel version: 2.6.18-238.el5 Server is virtual. Server has 2 virtual ...
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0answers
159 views

OOM killer kills process though page cache is never evicted

Our servers in production sometimes under load runs into the following issue (Linux 4.10): Application handling the load (webserver) is running at high load. A new job starts (e.g. cron). This ...
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1answer
368 views

How to prevent kernel I/O thrashing in absence of swap memory on Linux?

I had problem with a process spawning very many threads due to a bug, eating up memory, causing heavy swapping to the swap partition. Thus, I switched off swap – which is recommended in server ...
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1answer
519 views

Delete a file that was created with fallocate

I started to create a swapfile. I used this command: sudo fallocate -l 1G /swapfile Then, I decided that I want to make the swapfile in a different path, so I used the command again with the right ...
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2answers
1k views

Linux OOM disk I/O. Also: swap, what is it good for?

I'm having problems with the OOM killer on one of my Linux (2.6.37) installs. The computer has 4GB of memory which I sometimes utilize fully. In those cases, I expect the OOM handler to come in and ...
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1answer
274 views

dd using all memory and swap

I have a dedicated Centos 6.9 linux server with a company that crashed due to hardware failure and has been restored with the old HDD's on a usb caddy. I am trying to move lvm partitions over to the ...
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2answers
10k views

Solaris: how to list swap space per process?

On Solaris, how can I find out how much swap space a given process is occupying? Or even better, how can I list all running processes sorted by swap space usage? I'm asking this particulary for ...
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11answers
11k views

How big should the swap partition be?

for some years, I've read that it's a good idea to create a swap partition having the double space of my RAM. does it still apply today? or this isn't needed anymore? I have a server with 8 GiB of ...
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0answers
793 views

vm.swappiness works differently on CentOS 6 and 7

We have an Hadoop cluster of CentOS 6 (kernel version 2.6.32-504.el6.x86_64) and CentOS 7 (kernel 3.10.0-327.el7.x86_64) servers . All the nodes are configured with a swapinness of 1. All nodes have ...