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 it a bad idea to not have a swap partition on an embedded linux setup?

I have a small embedded linux kernel and file system created via buildroot that is installed onto a compact flash drive running on an x86 board. I am using an initramfs (due to power loss concerns) ...
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3answers
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kswapd0 takes 99% to 100% CPU in RHEL 6.3

I have 5 systems on which I have just installed RHEL6. System configuration is CPU-i7 HDD-500 GB RAM-2 GB Swap- 4 GB I have installed the same software's and all the configuration as per old ...
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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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866 views

How do I set up an encrypted swap file in Linux?

How do I set up an encrypted swap file (not partition) in Linux? Is it even possible? All the guides I've found talk about encrypted swap partitions, but I don't have a swap partition, and I'd ...
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395 views

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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365 views

Which processes swaps memory

I can see swap's total, used, free etc. sizes from top command. But I can't figure out which process uses swap, is it possible to find out swap memory by process? I'm running CentOS 6.3.
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How can I open a file in VIM in readonly mode if it already has a swapfile?

When I use the command :e filename to open a file and this file is already opened by another vim instance, I get a prompt asking me if I want to open the file in read-only mode, edit anyway, recover, ...
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Create swap partition after install

I already have parititon contain data under lvm enviroment with centos 5.8 output of fdisk -l root@server [~]# fdisk -l Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, ...
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510 views

What does m represents in VIRT column using TOP command

When we run top command it shows all the processes information. But under VIRT column there is m written against some values what does that m represents, is it MB . If yes then why it is only showing ...
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Swap usage too high?

I have a debian sid box, freshly installed about a month ago, with no desktop apps running at the moment. Any command I try to run (via ssh) makes the hard disk work very hard. The system worked ...
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637 views

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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191 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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885 views

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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1answer
402 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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344 views

zram swap instability

I use Mint 13 Maya with mainline kernel 3.6.3 for Ubuntu Quantal on my Asus P53E Notebook. I use zram swap that comes with the package zram-config. I've noticed that using it the system to hangs at ...
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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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1answer
958 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 is ...
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Swap space not used

I recently installed Debian 6.0.6. Here are the machine's states: CPU - AMD XP 3000+ RAM - 1 Gig HDD - IDE 80 Gig I primarily use this machine for developing toy personal projects. When I run ...
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Tmpfs only with RAM

How to be sure that a tmpfs filesystem can only deal with physical and it's not using a swap partition on disk ? Since i have a slow HDD and a fast RAM i would like, at least, giving higher priority ...
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1answer
1k views

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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How can swapoff be that slow?

Somehow I happened to swap out 14 GB of memory. After having killed the culprit, I have tons of free memory again, so I thought I could bring in the important data again. So with 5 GB out of 32 GB ...
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What command can be used to force release everything in swap partition back to memory?

What command can be used to force release everything in swap partition back to memory ? Presume that I have enough memory.
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1answer
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Why my partitions don't show the right capacity on a 4096 byte physical block hard drive?

After reading a lot about why newer 4096 byte physical block hard drives should be partitioned taking care of alignment (Linux on 4KB-sector disks: Practical advice, What is partition alignment and ...
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184 views

Can I accelerate swap by using multiple harddrives?

I still have two old ATA drives (one is only 8GB, one is somewhat defect) and I've been thinking about putting them into my PC and activating swap on them, too. What will be effect of this? Will my ...
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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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1answer
341 views

Can't add swap file on solaris

I'm trying to add a swap file on Solaris 10. I have already created a 2GB file swap.file. Then, I add a swap file with the command: swap -a /swap.file which shows an error: /swap.file: size is ...
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598 views

How to disable swap file after install or during Kubuntu install?

My computer has more than 64KB of RAM (8GB), if I run out of memory I want things to crash so I know I'm out of RAM so I'll buy some instead of say wandering why my computer is running slowly when I ...
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971 views

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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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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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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Is it possible to trigger OOM-killer on forced swapping?

Is it possible to have the system preemptively swap out inactive pages (vm.swappiness), but invoke the oom-killer when the system runs out of RAM (as opposed to running out of memory) and is forced to ...
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212 views

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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1answer
683 views

KVM and swap problem

So I have a problem, I'm managing a server and the swap partition is way too small at the moment. The machine runs KVM with about 24 VM's on it. The problem is that some of them are rather inactive so ...
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What is the appropriate value of vm.swappiness when using zram?

I'm using zram on my computer as a compressed RAM-backed swap. When the system needs to swap something out, swapping it to a zram-backed swap file is more or less equivalent to compressing that data ...
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Is swap an anachronism?

I've used unix for quite a while, and for the last couple years I've felt like swap is an anachronism, but I'd be curious what other folks think. My argument is roughly this (assuming no global ...
2
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1answer
550 views

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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What does the vm.swappiness parameter really contol?

Per the kernel documentation: This control is used to define how aggressive the kernel will swap memory pages. Higher values will increase agressiveness, lower values decrease the amount of swap. ...
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471 views

Java process, swap (/proc Solaris10) memory highly utilized

How can I analyze high swap memory utilization of Solaris 10 for Java processes?
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1answer
384 views

LinuxMint, unable to set swap partitions to equal priority

I only recently realised that you can specify multiple swap partition, spreading them across drives. Well that's great for me as my desktop system often uses swap space and I have three different ...
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1answer
809 views

Zram does not start at start-up

I am using pinguyos 11.10. Pinguyos is a variant of Ubuntu 11.10. I have installed zram like this: sudo add-apt-repository ppa:shnatsel/zram sudo apt-get update sudo apt-get install zramswap-enabler ...
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How to completely disable swap?

I am using Debian sid, hard drive formatted with ext4, running on linux 3.1 I remember on previous linux versions (maybe before 3.0), if I run out of memory, and swap is not enabled, programs will ...
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1answer
267 views

Is there an in-memory compressed swap facility (like Compcache) for FreeBSD?

Is there anything like CompCache for FreeBSD?
3
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1answer
818 views

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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1answer
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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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2answers
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How can I check if swap is active from the command line?

How can I check if swap is active, and which swap devices are set up, on the command line?
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Where to put swap space, at beginning or end and other swap questions

Where do I put my swap? Debian installation gives 2 choices: (1) at the end or (2) at the beginning of the disk space. What is optimal? What is the optimal amount of swap given my computer has ...
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2answers
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Does mkswap check that a partition is a swap partition before formatting it?

I checked the man page for mkswap and was left confused whether mkswap tests whether a partition is of type 82 before formatting it. Background: I am using Ubuntu 11.04, and I had just set up my swap ...
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804 views

Solaris swap allocation with mlocked shared memory

I'm having a hard time understanding how Solaris 10 x86 swap allocations work in the presence of mlocked share memory. I wrote a small program that: Gets a 1G SHM segment (shmget) Attaches it to ...
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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 ...
2
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1answer
959 views

Mysql / swap space full

I have MySQL Ver 14.12 Distrib 5.0.45 server running on Multiflex Intel Blade having 8G of RAM & 8 x Intel(R) Xeon(R) CPU E5410 @ 2.33GHz. The problems I am facing are: For the last 3-4 days ...