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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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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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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385 views

Is clearing a full swap necessary / wise?

We have a linux machine, in which the swap partition gets filled to the limit from time to time. There's still enough of RAM free, so there should be no risk of running out of memory. The usual course ...
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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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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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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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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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751 views

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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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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383 views

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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1answer
225 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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1answer
607 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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624 views

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 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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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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172 views

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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2answers
1k views

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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2answers
623 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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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 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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1answer
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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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1answer
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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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1answer
727 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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1answer
1k 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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1answer
887 views

What are the advantages of swap on a raid-1 (mirror) device?

What are the advantages of swap on a raid-1 (mirror) device? (in a server environment running linux) I mean, you can just use multiple disk devices in linux for swap. And with swap devices that have ...
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3answers
94 views

8G RAM and SSD - how big should the swap be?

I have a computer with 8G RAM and a 128G SSD. I don't plan hibernating. What swap size would you recommend? Would you change any swappiness? In the nearest future I'll compile programs (or even ...
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1answer
61 views

What happens when a tmpfs volume is full and swap is full? Is Linux's OOM-killer involved? [duplicate]

I understand that if a persistent / disk-based volume is full, files need to be explicitly deleted to free up space before more can be added. Further, I understand that if memory is exhausted, the ...
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1answer
170 views

Luks Partition Mounting After Removing From fstab

I have 3 encrypted partitions, one for /, one for /home, and one for swap. It seemed silly to me to type in my password 3 times, so I replaced the swap partition with a swap file on the encrypted ...
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621 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
432 views

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

Is there anything like CompCache for FreeBSD?
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1answer
34 views

How to prevent swapping on Mac OS X?

I am inclined to run Tails through a virtual machine so that I could chain two VPNs. One running through the host Mac osx and one more running from inside the virtual machine that's running Tails. ...
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1answer
28 views

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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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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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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Out of Swap - What happens?

On my debian VM machine with 512MB RAM and 348MB Swap, what will happen if i open a 1GB file in an editor and get out of memory? Will it crash the system? Or if not, how will linux handle this? ...
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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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2answers
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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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1answer
2k views

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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1answer
579 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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1answer
955 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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1answer
4k views

Process Monitoring on Solaris

$ prstat -t NPROC USERNAME SWAP RSS MEMORY TIME CPU 164 oracle 5446M 5445M 8.3% 13:47:50 1.6% 52 root 576M 728M 1.1% 42:29:50 1.0% 1 noaccess 300M 273M 0.4% 0:20:54 0.0% ...
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Can linux systems on multiple virtual machines share the same swap partition? [duplicate]

I'm trying to save some disk space between multiple systems and re-using the same swap partition (which seems to be fine). I'm now getting into multiple virtual machines and am thinking of a ...
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685 views

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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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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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 ...