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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Is there way to force Linux to unswap when there is low CPU usage?

After working more than 1 day on my machine swap becomes about 1GB. Some of my panel plugins go to swap so they become laggy. Moreover system doesn't unswap until I make it to do it swapoff ...
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152 views

Will SSD swap improve performance?

I am wondering if i have only 4GB ram and somehow(virtualbox,browser) isn't enough and i cannot proceed to upgrade(due to ultrabook and soldered memory) will swap held in SSD help the overall ...
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3k views

Extending swap on Centos

I recently created a swap file on my centos 6 based VPS using this guide. Now I wanted to extend this swap and I was reading through this guide. However, I think I've created a swap file than a ...
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140 views

Does asynchronous disk IO affect swap usage?

I have a server application requiring usage of huge memory but can take little time. I therefore thought it should be economical to run it with a big swap and normal ram. I was reading about serving ...
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600 views

Turn on Swap after resize /

I resized with lvresize the swap from 4 to 2G and can't turn it on. swapon /dev/VolGroup/lv_swap swapon: /dev/VolGroup/lv_swap: swapon failed: Invalid argument lvdisplay /dev/VolGroup/lv_swap ...
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2k views

Drop_caches doesn't drop caches?

Sometimes I see my swap file is a bit bigger then usual. I tried sync && echo 3 > /proc/sys/vm/drop_caches to no avail. But when I tried swapoff -a it takes a bit longer but the swap file ...
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2k views

Debian hibernate problem PM: Swap header not found

I have Debian 6 2.6.32-5-amd64 on netbook. With pm-utils Sleep works but hibernate fails with error: PM: Swap header not found!. Swap was enabled using ubuntu tutorial after installation - this is ...
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607 views

Is there a way to kick kswapd and make it swap out pages?

Even though I have set swappiness to 100 and enabled swap, nothing is being swapped out. This is probably because I don't have high memory pressure at the moment. For testing purposes though, I want ...
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982 views

What is excessive swapping

This post led me to ask that question. Cache contention On a large site, if you are using MyISAM, contention occurs in the database tables when the cache is forced to clear after a node ...
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35 views

how to make swap permanent in vm?

I create the ubuntu vm by vagrant. I want to add the swap to vm. the steps: mkdir /swapfile cd /swapfile sudo dd if=/dev/zero of=swap bs=1024 count=2000000 sudo mkswap -f swap sudo swapon swap add ...
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Fixing fstab after reformatting swap

I just made a small mistake and reformatted my swap partition. It's still formatted as a swap partition - I was fortunate not to touch anything more important. However, I notice that the uuid has ...
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109 views

On page fault, how does Unix determine if the faulting address is in swap space?

When a page fault occurs for a virtual address for any process how does the linux/unix operating system determine whether that page (of that virtual address) was swapped previously present in memory ...
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158 views

Is it safe to delete all swap partitions?

More explicitly: If it safe to shutdown a system, boot from a live cd, delete all disk swap partitions, and boot the system? This is in follow up to How to safely turn off swap permanently? (on ...
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VGEXTEND: How to avoid wiping a swap signature in /dev/sda3?

The problem: [root@195623 ~]# vgs VG #PV #LV #SN Attr VSize VFree fedora_195623 1 3 0 wz--n- 9,50g 0 [root@195623 ~]# vgextend fedora_195623 /dev/sda3 WARNING: swap ...
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192 views

Calculating RAM/Swap Space Requirements [duplicate]

I have been developing a MySQL database that makes some use of BLObs. This has now been transferred on to a virtual machine (VM) in preparation for going fully into the 'cloud'. However some of the ...
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331 views

OpenBSD runs out of memory, while not using swap space

I'm working with a fresh install of OpenBSD (5.6 amd64). I'm attempting to build Boost libraries, and quite a few compilations are failing with cc1plus running out of memory errors. I've read ...
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168 views

Fastest and Safest way to increase Swap Space on Scientific Linux

Memory Swap Ratio Company System Today, a monitoring system indicated that one of the systems in the company has run out of memory. Executing htop on this system indicated that the Memory was nearly ...
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87 views

Something happened to Swap; it is not used by default

I always have to go to gparted and then turn my swap on. The swap space isn't used by default and if I turn the swap on, the swap is not used! How can I make the swap space be used by default at boot? ...
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How to re-enable hibernate in Kubuntu 11.10?

After making some changes to my swap space, namely deleting and recreating swap space, my Kubuntu 11.10 has lost hibernate functionality. Although the button has returned, hibernating only appears to ...
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hibernation and swap partitions on ssd/hdd

I'm quite a beginner in Linux and I've got some problem to decide: I've got a laptop with two disks - 1TB HDD and 256 SSD, and 12GB RAM and I want to install debian on SSD. I used hibernation a ...
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24 views

What happens if my RAID fails while the swap is on it?

Today I removed swap from the system drive on my Debian. And created a swapfile on md0. So, I have a RAID1 array for data and a swapfile (the only swapfile). The system with boot partition is on ...
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89 views

How to add 100MB of swap space as a logical volume in CentOS?

I need to add 100MB of swap space to my machine. I was trying to use a logical volume. # lvcreate –name lv_swap2 –size 100M vg # mkswap /dev/vg/lv_swap2 # swapon /dev/vg/lv_swap2 # vi /etc/fstab ...
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SWAP write protection on SSD

When using SWAP on an SSD, does the filesystem offer any write-cycle protection? i.e. randomizing or otherwise managing writes to avoid "flash wear-out" since modern SSDs are generally rated in the ...
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85 views

How are the values represented with the “free” command

I am interested in the totals of the 3 lines. Specifcally, if the "used" values can be counted as what's going on in real time, or if that's just a running total since the OS was started? How does ...
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770 views

How to find the swap uuid

I am in the process of setting up a raid. sda was used during the installation and I just copied the partition table of sda to sdb like so: $ sudo sfdisk -dL /dev/sda > partition_table_sda $ sudo ...
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61 views

How do I know I should turn swappiness down?

I have 5.5 GiB memory, using 2.8 GiB (~50%), but my swap is using 1.9 GiB of 5.6 GiB (~33%). My computer operates okay but is sluggish at times. So is this a high amount of swap usage or completely ...
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381 views

how partition for OpenSuSE dual-boot

Currently I'm running Ubuntu 14.10 and have quite a bit of free space on this disc: thufir@doge:~$ thufir@doge:~$ sudo fdisk -l Disk /dev/sda: 465.8 GiB, 500107862016 bytes, 976773168 sectors ...
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151 views

When the RAM is used up, what will happen?

When I ran ImageMagick's convert to convert and combine image files into a pdf file, it will create 10GB temporary dirs and files in /tmp. I am not sure if it did that all the time, or because my ...
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989 views

How to enable swap accounting for memory cgroup in Archlinux?

On my Archlinux box I want to limit some applications to a smaller amount of memory using cgroups. Since I use swap, I need to account memory+swap. How can I enable swap accounting?
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173 views

Allocation of Swap in 64 bit UBUNTU 13.04

I have 256GB ssd drive, 32GB DDR RAM, and 1TB HDD. What is the maximum limit of Swap memory that can be set in SSD?
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66 views

Is zswap eligible to reduce swap IO?

Does zswap compress pages, that are written to the swap device? Is it eligible to reduce swap IO?
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free / top difference. Does free show virtual memory?

free -m shows me the following in my system: total used free shared buffers cached Mem: 3954 3842 111 0 248 2585 -/+ ...
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Swap Utilization Increase with Oracle Coherence

We are using Oracle Coherence on linux servers. However, we noticed that because of Coherence processes running, often our swap utilization % increases too much, sometimes becoming more than 98%, even ...
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Recover from faking /proc/meminfo

So, without really thinking too much, I ran this script: #!/bin/bash SWAP="${1:-512}" NEW="$[SWAP*1024]"; TEMP="${NEW//?/ }"; OLD="${TEMP:1}0" sed "/^Swap\(Total\|Free\):/s,$OLD,$NEW," /proc/meminfo ...
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Real-time monitoring of changes in swap use (per process)

I'm looking for a way to observe which processes in my system are consuming an increasing amount of swap over time. The following function generates a list of swap user per process : sbp(){ grep ...
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Creating a sparse (automatically expanding and contracting) swap file with hole-punching support

I have this crazy idea, and want to know the pitfalls of such an approach (or whether it can even work with no deadlocks.. etc). The goal is to create an automatically expanding and contracting ...
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When hibernating : “PM: Swap header not found”

I've already seen Debian hibernate problem PM: Swap header not found, but the difference is that it's not a file swap but actually a swap partition. I'm on Ubuntu 15.10. My swap partition: $ ...
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Restoring in-memory/swapped page state on resume from hibernation

I'm a big fan of Linux's hibernation support, which works extremely well on all the (admittedly slightly older) hardware I've tried it on. I highly prefer it to full shutdown and power up. There's ...
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26 views

Old Xen Installation Unable to be Formatted

I recently tried to format a disk that had an old Ubuntu 14.04 partition and a Xen Swap Disk partition. I am currently running the Ubuntu Live CD and trying to access my partitions on the drive for ...
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What is kswapd_low_wmark_hit_quickly from /proc/vmstat

What does this parameter mean? # cat /proc/vmstat | grep low kswapd_low_wmark_hit_quickly 2
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Which parts of Memory can Swap Support

For this question, "swap" does not include RAM and only refers to the configured space on the disk. According to, http://www.ualberta.ca/CNS/RESEARCH/LinuxClusters/mem.html, a program's memory usage ...
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56 views

Swap output in last x minutes

Is there any command or script to give o/p as " swap used in last 10 minutes is x" ? I wished to use that out put for my nagios monitoring.. I have used SAR in my below script and is trying to run on ...
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217 views

Ubuntu 14.04 using 100% swap space, with more than 40GB free memory, why?

I'm a bit at a loss trying to figure out why this would be the case. Can anyone provide some helpful ideas on troubleshooting this? $ free -m total used free shared ...
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108 views

Out of Memory with unused memory and swap

I have a strange error on my Raspberry Pi2. System is archlinuxarm. Short after boot (about 30 secs), the system states that it is out of memory, resulting in closing many applications, most time ...
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233 views

Process Being Killed due to low swap

I'm running a python (2.7) script on mac osx yosemite. The script is fairly computationally intensive, certainly bumping up against my machine's RAM limitations. The computer crashes and restarts ...
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276 views

Java process gets killed frequently by OOM - Killer on upgraded hardware

I am running solr on an Ubuntu server along with 4 other java processes. Current index size is 30 GB. My solr process gets killed frequently in few hours. It clearly mentions that its an OOM killer. I ...
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unlimited tmpfs

How to have the advantages of tmpfs and not be limited to its small size? I'm thinking of a shell script that runs as a daemon, monitors RAM and adds more swap files in specified folder, when memory ...
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616 views

full disk encryption (including swap, possibly plausible deniability as well)

I'm looking for a method to encrypt my laptop including the swap partition. I also read trough older similar questions but mostly the answer included just a what not much of a how. (Currently I'm ...
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Swap appears to not be in use

(I am currently using Ubuntu 14.04 LTS, GNOME environment) tl;dr How can I force more memory swapping (swappiness already at 100)? I have recently been experiencing a lot of system freezes/crashes. ...
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Xeon Phi swap from host's tmpfs

I want to use swap on Xeon Phi (mic0) using RAM from the host On the host: # free -m total used free shared buffers cached Mem: 129022 60312 ...