Questions tagged [swap]
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.
4
votes
2answers
392 views
Why swap space doesn't get filesystem check at boot time?
As I was checking the /etc/fstab I noticed that the swap space has attr pass=0, which means its filesystem is not checked at boot time.
Can anyone please tell me why is this behavior for?
1
vote
1answer
47 views
Is turning off swap a good idea when a system has available RAM and swap being used?
I have a system with 4 gigs of RAM and an SSD. I heard allocating swap on SSD is a bad idea because SSD has got limited write cycle.
So when I see < 100 MiB of pages is written to the swap, and I ...
2
votes
1answer
44 views
Why is swap so large when I try Peppermint OS on live usb? (The usb's size is smaller than the swap's size)
I try Peppermint OS (a distro based on Lubuntu) on live usb. I check ram by the command
free -h
and the result is
peppermint@peppermint ~ $ free -h
total used free ...
0
votes
1answer
13 views
How to “Resize” Swap File in Centos 7
i see a number of explanations referring to resizing swap partitions, however, i cannot find one that explains how to "resize" an existing swap file?
my existing /swapfile1 is 512 MB
i want to ...
0
votes
0answers
22 views
how to make sure Ubuntu 16.04 use swap only when memory is truely used instead of full of cache?
I have already set vm.swappness to 0, but the system still uses swap after sometime the rest of memory is filled by cache. This leads to high load and high latency, probably because I put SWAP and the ...
1
vote
0answers
23 views
atop shows `swout` (swapping) when I have gigabytes of free memory. Why?
Why did atop show that I was swapping out over 20,000 pages - over 80 megabytes - when I had gigabytes of free memory?
atop refreshes every ten seconds. Each refresh shows the activity since the ...
5
votes
1answer
260 views
What are the holes in files created with fallocate?
If we create a swapfile with fallocate we are told that the file contains holes and therefore the operation is halted.
What are these holes?
Is it unallocated disk space, which makes the whole file ...
1
vote
1answer
32 views
Is `vm.swapiness=0` equivalent to `swapoff -a` (in kernel >= 3.5)
Is setting in /etc/sysctl.conf:
vm.swappiness=0
equivalent (except that it's persistent) to running swapoff -a, *in Linux kernels >= 3.5?
*in earlier kernel versions, 0 meant 'no swapping until out ...
2
votes
2answers
87 views
Why does Linux write to swap space even if the system has available storage while copying a big file to somewhere?
I have been noticing that if I copy a file to some storage device (the system's HDD, SSD, or to a thumbdrive) a small amount of data (20 - 30 MB) is written to the swap space - and the count increases....
0
votes
1answer
65 views
MacOS,no swap commands?
Usually on various unix flavours for swap we have
Those commands to see swap usage and activation
of swap
On Linux
free
swapon/off
On Hpux
swapinfo
swapon/off
On AIX
swap
...
2
votes
1answer
66 views
Is there a per-user swap file?
I found out, I want to encrypt a swap, but it won't be detected by other users, or more like even corrupted. So swapfile for each user sounds like a nicer concept. Then it would be encrypted if dm-...
2
votes
2answers
133 views
Why does RHEL use swap even when vm.swappiness = 1?
RHEL 7.2 memory use, per free -m:
total used free shared buff/cache available
Mem: 386564 77941 57186 687 251435 306557
Swap: ...
4
votes
3answers
175 views
Linux swap file creation and management
I want to increase my swap size to be able to have the hibernate option. First, I tried to add some swapfile. I followed
https://bogdancornianu.com/change-swap-size-in-ubuntu/
and typed this in my ...
5
votes
3answers
225 views
Despite ` vm.swappiness=100`, Mint system freezes, yet swap underused
My Mint 18.1 system often freezes for approximately 10 minutes due to running out of memory, as per a widget which shows 100% memory use at freeze time. SysRq + "Raising Skinny Elephants Is Utterly ...
1
vote
0answers
37 views
Hibernation with encrypted home and swap without initramfs
I have a Linux setup with an encrypted /home/<username> (LUKS) and without an initramfs. I currently have an unencrypted swap partition, intended for hibernation. For security reasons, I would ...
2
votes
0answers
51 views
Do I have a swap space leak in FreeBSD?
I have a system with 16G RAM and 23G Swap (6 x 3TB disks in ZFS), currently the swap sits at 98% but I can only see 5G of ram used.
I have checked all possible resources to find who is using the swap ...
1
vote
0answers
26 views
How can I enable asynchronous swapping using a kswapd thread in a cgroup resolution?
I would like to enable active swapping (using a background daemon) on my cgroup even before the entire system is suffering memory shortage.
I have a 128GB Linux host and a cgroup that is limited to ...
-1
votes
1answer
238 views
error messages::ext4-fs error(device dm-0) after write-error on swap device
recently, i moved fedora29 into the desktop harddrive from external hard drive
(Miraculously, i installed fedora29 on external hard drive anyway ^^:)
as installed as soon, it was too slow. i added up ...
0
votes
1answer
160 views
Why are there no values for 'shared', 'buff/cache' and 'available' in the swap line of free?
Why are the last columns empty in the swap line?
$ free
total used free shared buff/cache available
Mem: 3912864 2255460 315388 249068 1342016 ...
0
votes
2answers
45 views
Why do we need both mkswap and /etc/fstab to set up swap?
Given
$ cat /etc/fstab
...
/dev/mapper/lubuntu--vg-swap none swap sw 0 0
why do we still need:
$ sudo swapoff /dev/mapper/lubuntu--vg-swap
$ sudo mkswap /dev/...
0
votes
1answer
43 views
Can't log in desktop environment after moving `/` and `/home` into different LVs and enlarge swap
I enlarged LV swap from 1G to 4G. I also moved / and /home in a single PV to two different LVs, by shrinking LV root and create LV home on the freed space, and then following https://askubuntu....
0
votes
2answers
67 views
Is swap a partition, but not a file system?
Is swap a partition, but not a file system? Is that the reason why df doesn't show it?
Is there a command which can list all the partitions (whether they hold file systems or not)?
Thanks.
$ df -h
...
9
votes
1answer
475 views
Why can't I “swapoff” when there's plenty of memory?
I've recently noticed that even though there's a lot of memory on my system:
# free -m
total used free shared buffers cached
Mem: 15965 9680 ...
1
vote
1answer
70 views
Sharing swap partition between Ubuntu and Kali
I am making a fresh install dual-boot for kali and ubuntu. I had this question in my mind if I will create a swap-area of 32GB (16 Gb RAM) will it work for both the Linux distro?
38
votes
6answers
3k views
How do I use swap space for emergencies only?
I have a Debian (Buster) laptop with 8 GB RAM and 16GB swap. I'm running a very long running task. This means my laptop has been left on for the past six days while it churns through.
While doing ...
1
vote
0answers
22 views
High swapiness on VM host
Would setting very high swappiness so that more RAM could be assigned to VM impact performance? I would assume that VM related tasks wouldnt be swapped, and the tasks within the VM.
0
votes
0answers
52 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 ...
2
votes
3answers
192 views
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 ...
2
votes
1answer
400 views
Why does swappiness not work?
We have a RHEL 7 machine, with only 2G of available RAM:
free -g
total used free shared buff/cache available
Mem: 31 28 0 ...
2
votes
1answer
329 views
How to limit swap usage in Solaris?
I have an Oracle Solaris 11.3 which has 128 GB of Memory (RAM) and 80 GB of Swap.
I want to limit the use of swap space (not its size just the usage).
I know in more modern linux distros ...
0
votes
0answers
17 views
How to resume system (from disk) manually
I suspend the system to disk using s2ram. When I reboot into shell (busybox sh) and run resume $SWAP ($SWAP is my swap partition), it only writes a message that says resume is started but nothing ...
2
votes
0answers
38 views
Swapping takes 20% of cpu cycles, is this thrashing? [closed]
I run a long bootstrapping compilation. I have 16G of physical memory but my main process attains 32G virtual memory.
UPDATE (response to Austin Hemmelgarn's comment): This is on a two core Intel ...
1
vote
1answer
145 views
Will swap file engage automatically when I write too much to /dev/shm
Text analytics programming today. My program is going to write about 45 million small temporary files to /dev/shm and their size estimate is 177.0 GB. I'm going to delete them soon after the next ...
0
votes
1answer
100 views
Process is stuck with more virtual memory than physical memory available
I have a process that seems to be stuck in an interesting way. top shows this:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
38984 gergely 20 0 332m 276 184 S 0.7 ...
0
votes
0answers
15 views
Migrate old swap to slow storage
On a machine I have 2 swap partitions: A fast one (on SSD) and a slow one (on magnetic media).
I use the fast one as the first priority.
Can I migrate the pages that have been untouched in the past, ...
2
votes
0answers
285 views
Swappiness set at 100, but is empty nonetheless
Backstory:
So, I have a vm running and managed to open enough browser tabs to make linux mint freeze completely, by filling up both swap and ram. Then swappiness was at 60. So after this happened a ...
1
vote
0answers
34 views
How to force the kernel to always maintain at least some page cache?
Is there any way to force the kernel to always maintain at least some page cache for writeback caching purposes, even when faced with memory pressure?
I have a rather special use case, where swapping ...
0
votes
0answers
335 views
How do I make my system only use swap when RAM is totally full?
In the past, setting vm.swappiness to 0 meant the system would only swap when RAM was totally full.
$ cat /etc/sysctl.d/99-sysctl.conf
kernel.sysrq = 1
vm.swappiness=0
$ sysctl vm.swappiness
vm....
-2
votes
2answers
214 views
Swap partition and swap file at the same time?
I've added the swap file while having the swap partition:
NAME TYPE SIZE USED PRIO
/swapfile file 4G 6M -1
/dev/dm-0 partition 1,9G 0B -2
The size of RAM is 4GB. I'm on ...
0
votes
1answer
38 views
Can I distinguish between swap thrashing and non-swap high IO latency somehow?
My system becomes much, much less responsive, every time I clone a VM image. I'm using virt-manager, and I can see the IO is performed by several qemu-img convert threads.
I tried to gather some ...
0
votes
2answers
25 views
How to record max value of swap during period?
I have some script that consumes a lot of swap memory.
How can I measure maximum swap load during script execution period ?
Is there any specific bash cli tool for my task ?
0
votes
0answers
24 views
Set minimal amount of disk read cache
I have slow HDD and 5.5 GB of RAM, and thus I'm using zram and no any disk swap.
According to my observations, the lack of disk cache has much worse impact on performance than active swapping. While ...
3
votes
1answer
32 views
forcing a process into swap and restoring it into memory
I'm doing some tests in Debian Linux on an arm sbc. There seem to be some issues which I couldn't confirm if it may be related to my zram swap setup.
Is there a way when I run a particular program to ...
2
votes
0answers
718 views
Dependency failed for swap, (boots warning at startup) [closed]
After accidentally formatting by windows (I use kali alongside win as dual boot), I entered into grub rescue, and did the usual stuff to recover grub
set prefix=(hd0,gpt2)/boot/grub
set root=(hd0,...
5
votes
1answer
211 views
Ubuntu 14.04 32 bit swapfile max 60k issue
Have a strange issue where suddenly all my swapfile (1gb each) get truncated to only use 60k . I can remove/recreate etc but whatever i do , the max seems limited to 60k with following message in ...
-1
votes
1answer
252 views
Swap on secured partition is not being mounting on boot
I've got a work laptop Lenovo P51. There is Win10 on a secured partition. I installed Ubuntu 18.04 on a secured partition as well. Also, I've created a secured partition for swap, but it doesn't mount....
8
votes
1answer
923 views
How can I zerofill the /swapfile without wiping out what makes it a swapfile?
I have a script that I run in order to optimize the disk space prior to backing up a virtual guest (really doesn't matter too much which hypervisor is used).
Modern Ubuntu versions (e.g. 18.04) seem ...
0
votes
0answers
105 views
Building custom kernel with kswapd0 disabled
What are the necessary kernel .config options changes for a kernel with disabled kswapd0 ? ie. what options to ensure exist inside kernel .config file such that it builds with kswapd0 disabled?
The ...
1
vote
1answer
31 views
Order of magnitude of when vmstat's swap si/so must be considered unhealthy?
With vmstat I can see in the swap si/so columns how many blocks are read/written from/to the swap per second. I have a system with tight memory and therefore need to make use of the swap. Which is ...
1
vote
3answers
207 views
How much swap space does Solaris 11.3 need to run a compiler?
I have a desktop with a Core i5 3rd gen and 4 GB of RAM. I am using the machine to test building some free software projects I contribute to. The machine serves no other purpose.
I allocated 4 GB ...
