Swap space is an area of the hard disk that serves as an overflow when the computer memory is full. The memory used by inactive applications is partially written out to disk to make room for other applications and for the disk cache for active files.

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When does swap start to be used? When does a process get an out of memory error and be killed?

When does swap start to be used? Is it when the memory is fully used? Or when the memory hasn't been fully used? When does a process get an "Out of memory" error and be killed by the kernel? is it ...
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Where is the virtual memory stored on hard drive?

If a process wants to access a memory address that is not in physical memory, the OS outsources a page frame from physical memory to the hard drive for later use. Where on the hard drive is this data ...
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Linux (3.4) SSD swap partition usage causes extreme latency - how to eliminate?

I'm running on 4G RAM with an extra 6G swap partition, SSD is a pretty decent SAMSUNG MZMPA128HMFU model. System responds very well to workloads when things stay in RAM, but as soon as things reach ...
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Does swap need to be on a contiguous LVM logical volume

I am setting up a machine to run a number of virtual machines. I am using a single HDD with a boot partition and an LVM partition. I read on the Arch wiki that logcial volumes which will be used for ...
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can initramfs be paged out to swap disk?

I am using initramfs to boot Centos via PXE. The initramfs used memory is listed within the "cached" value in /proc/meminfo or via free. Since I need to calculate performance data, I need to know ...
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What does it mean exactly when a processes “Time” has stopped in top?

I'll be looking into why we're getting critical swap alerts, and I'll find something like: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ SWAP COMMAND 14683 user1 30 10 16.0g 772m ...
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How safe is it to increase tmpfs to more than physical memory?

My server has 2GB RAM and 120GB SSD, plus some RAID arrays for storage. OS is Debian 8 (Linux 3.16). I have a MySQL intense application that has tmpdir = /run/mysqld, which is a tmpfs configured by ...
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What is the use/meaning of 'swap area' while linux installation?

When i installed ubuntu in my x86 machine, I had to configure some memory as 'swap area'. What is the use of this memory and what is the importance of this memory in linux file systems? How can I ...
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Can swap be shared safely while hibernating?

Suppose I have two different Linux installations A and B, both using the same swap partition. As I understand, running A or B will cause no problems with swap as only one of them is using it at a ...
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What about no swap?

I have a netbook with a very slow (especially on writes) SSD, would it be a good idea to go without swap? The way I see it is that code and unmodified pages will still be swapped (re-read) but I won't ...
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Does the order of partitions matter much?

I've just ran a test install of Arch on a separate computer, and now I'm ready to do the real thing on my main one. However, since the guide didn't explicitly recommend it, I did not install with a ...
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How can I tweak the kernel for total swap out?

I would like to deploy the following swapping policy: By default all pages in memory should also be in swap space. When a page in memory is changed (i.e. dirty), the page should be written out as ...
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Copying large file causes excessive swap

On a mid-class CentOS 6.4/64 server with 32 GB RAM, 3 TB free disk space, operating as KVM hypervisor, I start copying a 200 GB file to a destination in the same local filesystem. In fact, this file ...
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How to configure swap space after system instalation?

I've installed Debian Wheezy and after installation completed, I realized that I forgot to set the swap memory. So now, how can I configure the swap space?
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Linux running slow with 0 swap left

Our Linux server is responding very slowly. top doesn't show any excessive CPU usage. I noticed that even though there's about 5GB of free memory, the system is using all of swap with no free swap ...
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Why can I only have a limited number of swap files

This is a theoretical question. Why can I only have 29 Swap files/partitions? If I wanted to generate 10k 1MB swap file and swap them on, it fails at the 30 swap file with swapon: /tmp/swap29: ...
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Permanent swapping with lots of free memory

We have a Linux server running Debian 4.0.5 (Kernel 4.0.0-2) with 32G RAM installed and 16G Swap configured. The system uses lxc containers for compartmentalisation, but that shouldn't matter here. ...
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When is swap triggered or how to calculate swap_tendency?

I'm trying to use Redis for production services and trying to avoiding swapping, which is bad for performance. I had learn that swap is triggered by swap_tendency which is depending on ...
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tmpfs and vm.swappiness

I have started tuning a bit Linux VM performance on my system (yes. I know that vm.swappiness=0 will kill kittens but I found 30-40 as much better for me as it improved my latency - probably at cost ...
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Pulling all of a process's swapped memory out of swap

How would one go about quickly pulling all of a process's swapped memory out of swap without writing to disk? The context on this issue is trivial, as the systemic issue necessitating the question ...
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366 views

Resize XFS home directory in LVM

I am desperately trying to increase the swap space available to my server from 4GB to 16GB, however at present XFS + something is making this impossible. I have a single SSD hosting the OS (CentOS ...
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337 views

Why is my swap not being activated automatically via fstab?

I've got a Linux embedded system that I'm experimenting with (the Elektor Embedded Linux Made Easy board, based on the GNUBLIN http://en.gnublin.org/index.php/GNUBLIN-Elektor). I'm using the 3.3 ...
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683 views

How to stop waking all attached drives on reboot / deactivating swap?

A fresh install of Debian 6.0.6 for a system has 13 SATA drives attached. 12 refurbished WD-10EARS drives are yet unpartitioned. 1 WD1500BLFS drive is configured for OS and swap. Swap partition is ...
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Encrypted filesystems with swap partitions

A common error that happens with Ubuntu, though not Ubuntu in particular is the options of being able to encrypt the file system at installation time which creates an encrypted swap partition with ...
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Spike in swap utilisation without high swap rate

Every Saturday, for reasons unknown to me, one of my servers experiences a spike in swap utilisation. It's not necessarily a problem as there is plenty of free memory available, but I'd still like to ...
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How do I configure systemd to activate an encrypted swap file?

My previous question produced the commands to add an encrypted swap file: # One-time setup: fallocate -l 4G /root/swapfile.crypt chmod 600 /root/swapfile.crypt # On every boot: loop=$(losetup -f) ...
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Silent disk errors and reliability of Linux swap

My understanding is that hard drives and SSDs implement some basic error correction inside the drive, and most RAID configurations e.g. mdadm will depend on this to decide when a drive has failed to ...
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Can I mark _current_ memory contents as non swappable?

Background: in my linux (ubuntu) workstation, I want to run some experiments that allocate more memory than the physical RAM while I do other 'normal' stuff in the GUI. Problem: I have plenty of ...
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I need to take the output of command and make it the name of a file using a script [duplicate]

I am working on a way to integrate our Linux machines into our SCCM Reports. One of the things we would like to do is verify the swap size on the machines. I know that I can get the swap amount on ...
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How to reduce size of swap after a system is already installed?

I'm running Debian Squeeze 6.0.5. Does the use of swap memory make my computer run slower? If so, how can I reduce the size of the swap memory after the system is already installed?
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Linux, SSD and swap

This article suggests not to create a swap space on an SSD drive in order to reduce its wear. On the other hand, it suggested here that swap space positively affects performance. Would it be a better ...
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Swap on tmpfs (Obviously a bad idea, but is it possible?)

This question originated with a joke between co-workers about increasing performance by moving swap partitions to a tmpfs. Clearly even if this is possible, it's not a good idea. All I want to know ...
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Linux doesn't drop FS Caches. Instead Memory starts Swapping

I'm quite confused about this behaviour of linux memory caching. total used free shared buffers cached Mem: 15953 14188 1765 64 ...
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Tool to force use FILE instead of RAM

I'm wondering why there is no such tool like ram2swap, similar to cpulimit in parts. E.g. There is program daemon.bin. Let's create temporary swap file ( 1 Gb ): % dd if=/dev/zero of=tmp.swap ...
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How to change swap partition from primary to logical?

I was installing Mint on dual boot with Win8 and I accidentally created primary swap partition. Is there any way I can change the partition type from primary to logical? Or do I have to delete those ...
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swapoff fails when overcommit_memory==2

I've disabled memory overcommitting by setting overcommit_memory=2. Now when I tried to swapoff, I get this error: swapoff: /dev/sda5: swapoff failed: Cannot allocate memory But I in fact have 0 ...
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Memory management, bias to swapping

I was having 768 MB RAM. In a general day MySQL was using 100-180 mb of RAM and MySQL was swapping 80-120 mb. I was having 50-60 mb free RAM. So I thought I should upgrade. Then I upgraded my RAM ...
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Is swapping enabled by default on common operating systems?

As a result of this question, I was a bit confused. After some research I found that swapping is enabled by default on Mac OS X. Swapping was furthermore introduced in Windows 3.0, so I believe it is ...
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How is paging managed in the absence of swapping?

How is paging managed in the absence of swapping. If that is the case, how will a page fault be managed? What I meant is, if there is no availability for swapping, then how is Paging managed. I ...
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Making a swap partition using lvm

When we make a swap using a regular physical drive, we just use fdisk and make a partition with type swap, using the swap code for that partition, followed by mkswap and swapon commands. But what ...
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Swap: Better to create a dedicated swap partition or to create a swap file?

is there a rationale when to create a dedicated swap partition vs. creating a swap file, for example like /tmp/swap? In my certain case, memory is kind of low (1GB), disk space on a SSD is pretty ...
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What is happening with the Linux swap partition data when running Windows via dual-boot

Hmm, I would like to know what is happening with the data on the Linux swap partition when the Linux system is turned off and by the next start the Windows operating system via GRUB2 will start. 3 ...
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How can I create a swap file?

How can I create a swap file on a Linux system? I know how to create and use a swap partition but can I also use a file instead?
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How much RAM needed for preventing use swap?

At my system always available some "Free" and "Inactive" memory, but sometimes system move couple megabytes to swap. Per night it maybe around 100MB, but for a few days in swap could be more than ...
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Why is swap used when a lot of memory is still free? [duplicate]

In the below 2.6.18 Linux Kernel (Red Hat) server, there is a lot of free memory, but I see some swap is used. I always thought of swap as an overflow when memory has been depleted. Why would it ...
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Command for swap info in HPUX itanium and HPUX PARISC?

I need to get commands for swap information in HPUX (both Itanium and PARISC) somebody please help.
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Is it necessary to encrypt a swap * file * if it will reside on an encrypted root filesytem?

I'm running Linux on my Laptop and wish to protect my data in case the machine is lost or stolen. I've configured an encrypted ArchLinux environment and have everything working the way that I want. ...
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Expand the size of swap partition

I did some partition size expansions of my centOs system and recover boot loader and file system successfully.I also changed the location and expanded the swap (5GB to 8GB) partition along with above ...
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Can swap space accomodate single process?

From what I understand, the swap space can be used to swap out inactive processes to free up memory. But can a single process take advantage of swap space? For example, if my system has little memory, ...
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Dynamically growing swap file on Debian

I know how to create a swap file and use it as swap. But I have to configure the size of the file beforehand and the space is used on the disk, if the swap is used or not. How do I create a swap that ...