[Solved] Do I need a swap partition /swap file?

Hello Arch Community.
I want to install Arch Linux on my Aspire V5-573G Notebook with 8GB RAM and a 120GB 840 Evo SSD from Samsung. So my question is, do I actually need a swap partition / swap file? I read the arch-wiki pages about swap and suspend-to-disk / suspend-to-ram, and the only thing thats obviously profiting from / needing a swap partition is suspend-to-disk, no other things are mentioned in this regard. Is a swap partition in any other way important?
Thanks in advance.
Last edited by Oedner (2013-12-21 12:41:19)

headkase wrote:Another question to ask is what will happen if you don't have a swap file and run out of memory? In that case the Linux kernel will randomly kill process' until there is enough memory again. Obviously that isn't very stable but that is what it will do.
No. The OOM killer is pretty darn tweaked these days and usually(!) kills the actual perpetrator. The alternative—disabling memory overcommitting and answering memory requests with an out-of-memory error—can result in unforeseen problems as well: What if it a system process is trying to allocate a few bytes for some random string, and what if said system process isn't equipped to handle ENOMEM gracefully and crashes, because the default policy on Linux is to overcommit and never answer with out-of-memory errors?
Just trying to play devil's advocate here. I'm not happy with the OOM killer either and I'd rather have a deterministic solution to out-of-memory situations, but I realize that it's probably not an easy problem to solve.

Similar Messages

Swap Partition Vs Swap file

Hi everyone!!
I am using Oracle 11g (enterprise edition) on linux redhat 5.5 . At present, we have 12G RAM and swap partition of 2G. I know that we should have swap area of 6GB as per RAM. But we are unable to create new swap partition or resize existing. So I want to know is should I create new swap file of 4Gb that can be used as swap area in addition to existing swap partition of 2Gb. So that total swap area will be of 6G
( 2G swap space + 4G swap file).
1. Will it be meaningful or not ?
2. Which one is better among swap partition and swap file ?
3. Will swap file cause performance degradation due to incompatibility between them ?
Thanks & Regards
Tushar Lapani

Swap is no substitute for RAM. It provides a fail-safe mechanism and allows the kernel to handle active memory allocation more efficiently.
Your requirement or conclusion about swap space may or may not be reasonable, depending on your desired configuration. As a rule of thumb, swap space is usually configured twice the RAM if you use 8 GB or less and equal the amount of RAM if you have 16 GB or more. If you have 64 GB of RAM, it does however not make sense to have 64 GB of swap space, because the performance degration should you ever need that much swap space will be very bad.
A swap file as opposed to a swap partition has some security and safety concerns, and some performance overhead because of using a file system, but it can be feasible. It depends on your I/O use and hardware.
However, you will probably want to configure your Oracle database to use kernel Hugepages using ASMM instead of AMM for best performance and efficient memory use. Kernel Hugepages, unlike POSIX shared memory (/dev/shm) used by AMM, will be pre-allocated at system startup and cannot use swap space.
Message was edited by: Dude!
Until kernel 2.4 it was considered that a swap partition is faster than a file, but with the improvements of kernel 2.6, the performances is almost the same. A swap file has the advantage that it can be easier re-sized or removed than a swap partition, but it can get fragmented or deleted by accident. For best performance it should also be located at the outer parts (beginning) of the disk.

Generate large swap file (Use qtparted to generate partition

Desire to generate a 30GB swap file in Linux using the full capacity of a hard drive as swap.
Can this be done with the arch0.5 install CD?
I assume I must skip the auto feature to do so. I do not know if the CD program will allow skipping the program install steps and just install lilo.
Perhaps someone has done a similar thing?

i3839;
Thanks for the comments.
The desired entry is not to hdd but to ram such that all operations take place in ram...no hdd used...no CD orDVD used (except tp start the ram install).
While in ram, all video is improved when uncompressed video is entered (.vob for instance) and the result is higher quality and better resolution.
The basic question is in reference to arch install CD and whether it can be utilized to generate a HDD with just swap (one or more partitions) .
My experience with the arch CD indicates it doesn't like the install to skip any steps. Perhaps I can try a partition install and then abort the rest. I think it will allow three separate swap (type 82) partitions: at the least one of 2GB. Perhaps it is programmed however, to require a root and a boot as well as a swap.
I suggest you read the previous post which describes the install to ram...called 'toram' in knoppix. This doesn't use the hdd, just the dvd reader. It can however utilize a hdd file entered in a dvd install....tohd.. and add the cheat code ...toram..
The end result is a ram only OS which can utilize USB hotplug devices for entry and storage, turning them off when not in use.
The present system here has 2.5GB of ram but it is not able to accept the DVD of 2GB when attempting ..toram. The same ...toram..cheat code is available for the CD version which operates well in ram (only 680MB). The use of swap to augment ram is recommended.
Dvd versions have close to 5GB of programs in compressed form in the 2.1GB DVD media.
I hope this post helps describe the need for the swap a little better.

Is it safe to have the swap file on a separate partition?

I've just bought a second hand MBP 2012 (9,2 I think) with a 500GB hard drive and Yosemite pre-installed. Not going to get into a debate about it here, but I want to regress to Lion or Mountain Lion until Apple improves Yosemite's bugs and software manufacturers improve compatibility. However, I wouldn't mind also getting to know Yosemite. So my plan is to partition my drive and keep Yosemite on one partition, have Lion on the other, and use Lion for day to day stuff for the time being.
Obviously this involves a shrinking hard drive. I have an image of Lion's installer on another partition in case I lose the DVD (which happens to me far too often), so at the moment my partition scheme breaks down as 10GB for Mountain Lion's installer, 100GB for Yosemite, and the remaining 390 (roughly) for Mountain Lion.
Since the Yosemite partition is quite small, would it work if I made a symlink from /private/var/vm to the same folder on the Lion partition? Both folders will never be in use at the same time, so I can't think of any reason this wouldn't work - which would mean that the slippage and the swap files would all be located on the bigger partition, and the small size of my Yosemite partition wouldn't be a problem. Obviously when the time comes I would get rid of the Mountain Lion partition altogether and make the Yosemite one a lot bigger, but would that be an ok setup for now? Would it degrade performance for any reason if the swap files were on a separate partition?
Anyone ever tried this?

Thanks for the answer. The project is stored, saved, or burned to a DVD.
When I put the burnt DVD in my "E" drive (or DVD player/burner) installed in my computer it comes up as a my project in "E" drive.
It is a complete Primire Pro CS4 project. I has all my edits and effects just like it does when I open it from my HHD.
I can put the DVD in my wives computer and it shows it is there but it will not open because she does not have CS4 installed.
So it is not a movie. It is an exact copy of what the project looks like on my HHD.
I can edit on it and do everything I did from the HHD copy.
Hope this helps. Please feel free to question my responces.
I really do want to clean up my HHD and start over with a single file. Hopefully gererated by the DVD.
It seems like I could delete my files. It would be like I made this copy and sent it to you to do a final edit and add menus. You would not have the origional files on your HHD.
After you loaded to you could then send it to your HHD and do whatever - Right?
Jim

I need to swap devices and phone numbers!

     So here is the deal... My plan has four lines (my mother, brother, sister and I). My sister used my upgrade and renewed my contract in December (extending my contract 2 years), however I planned on dropping my phone line. So I need to swap my device and phone number with my brother since his upgrade is in about a week (01/26/2015).
     I know that I can't explicitly swap contracts or phone numbers, but as long as my brother keeps his phone and phone number, and My family's plan can drop a line next week I am good. I would like to be able to take my phone number with me when I leave as well, but that is less important.
     A customer service rep manager told me about something called a TNI swap but then he forwarded me to someone who told me I was in the wrong department and lost my call. Do any of you know what I can do. Thanks

Ive "heard" it can be done...and its very sneaky. Technically that line is under contract, so if you take the number it cancels the contract. You just cant switch numbers on a contract. So if you are tied to the number then take it and pay the ETF. Otherwise, have him have your number and you have his. Guess it depends how important it is to you.

Swap partition VS Swap File system

Hi everyone!!
I am using Oracle 11g (enterprise edition) on linux redhat 5.5 . At present, we have 12G RAM and swap partition of 2G. I know that we should have swap area of 6GB as per RAM. But we are unable to create new swap partition or resize existing. So I want to know is should I create new swap file of 4Gb that can be used as swap area in addition to existing swap partition of 2Gb. So that total swap area will be of 6G
( 2G swap space + 4G swap file).
1. Will it be meaningful or not ?
2. Which one is better among swap partition and swap file ?
3. Will swap file cause performance degradation due to incompatibility between them ?
Thanks & Regards
Tushar Lapani

This is a 100 percent Unix question and has nothing to with Oracle RDBMS.
Please close this question here and post it in any Unix forum.
Sybrand Bakker
Senior Oracle DBA

Need swap file on E7 mass storage for additional R...

As we all know, E7 is the flagship Symbian phone with powerful function and capability but the designer has done wrong calculation for memory capacity so they only have 256 MB RAM. So, please add swap file feature like in PC OS using mass storage for extend RAM capacity. Thanks,

OHH THIS IS GREAT IT HAPPENS TO YOU,
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WHO CARES IF IT IS LONG OR NOT
IN INTERNET SLANG, A TROLL IS A PERSON WHO SOWS DISCORD ON THE INTERNET BY STARTING ARGUMENTS OR UPSETTING PEOPLE, BY POSTING INFLAMMATORY, EXTRANEOUS, OR OFF - TOPIC MESSAGES IN AN ONLINE COMMUNITY(SUCH AS A NEWSGROUP, FORUM, CHAT ROOM, OR BLOG) WITH THE
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Changing swap file location on tray-loader iMacs

This is not a question, but something I discovered that makes my old tray-loader iMac (the oldest iMac models) run Mac OS X much better.
As you may know, these oldest iMacs have an 8GB size limit on the boot volume. The largest stock drive on these iMacs was 6GB. That means if your upgraded hard drive is larger than 8GB, it must be partition so that the first partition is under 8GB (7.78GB on my iMac), and it must be the boot partition where the OS is installed (whether it's Mac OS X or 9).
In my case, I have a roomy 120GB hard drive (I believe the useable limit on these iMacs is 128GB). The first partition is just under 8GB, the second partition is the rest of the space, about 104GB. I have used every trick out there to move files (such as the iTunes music folder and most of my user/documents files) off to the second partition, to make free space on the boot partition as large as possible. So I have 3.5GB free on my 8GB boot partition. This is about 40% of the volume's total space so it seems pretty good, until you realize that most recent Macs have much more than the TOTAL 8GB I have, as free space on the boot volume. Mac OS X was just not designed to work well with small boot volumes...
Mac OS X uses the free space on the boot volume for its virtual memory "swap file." Considering these old iMacs max out at 512MB of RAM, virtual memory is being used quite a bit. But since space on the boot volume is very limited, low RAM and lack of free space can lead to performance issues. Here's what I observed. When I initially started up my iMac, I had about 3.5GB of free space. Over time, as I used more and more apps, that free space would diminish until I had only about 600MB remaining (as reported by a Finder window). At the same time, I noticed performance getting bogged down and more "chugging" sounds coming from the hard-working hard drive.
I've known about changing location of the swap file, but never tried it until recently. During the Mac OS X boot process, the Mac sets the location of the swap file. By default, the swap file resides on the boot volume (I believe most other Unix-based systems use a dedicated "swap partition" for the swap file). Since most recent Macs have large drives set up as one partition (and there is plenty of free space), and since many users have upgraded their RAM (and virtual memory is not as critical), swap file location is usually not an issue, and there is certainly no need to change the swap file location. However, on my iMac with an 8GB limit on the boot volume and 512MB of RAM, it made a noticeable difference.
I found one set of procedures on the web that was much better than the others I found for changing the location of the swap file.
http://www.math.columbia.edu/~bayer/OSX/swapfile/
On this page, there are two choices for Panther users. I used the one that works for both Panther and Tiger, because it appeared to me to be more straightforward. The author intentionally keeps the instructions somewhat technical to discourage users who are not technically inclined. I don't consider myself to be too "geeky," but I can follow instructions and type a few commands in Terminal.
After I changed the swap file location to a large mostly empty volume, I noticed much better performance when I have many large apps open at the same time. Performance no longer degrades over time, and the free space on my boot volume remains a constant 3.6GB.
The reason for this post is to share this information. Some users of these old iMacs may be noticing the same issues I had. This is a possible solution. However, if everything is OK with your set up, there is no reason to change the swap file location. If you try it, be sure to take the usual data backup precautions.
If anyone else has experience with changing swap file location, please post your comments here.

Problem has been solved:
background.setCapability(Background.ALLOW_IMAGE_WRITE);Thanks everybody for reading this :)

Moving swap file

Im trying to find a better way to change my swap file location to my secondary drive in OS X.5. Currently I have set a symlink to /Volumes/MacOS_Swap/.vm from the origional /var location (after removing the previous directory).
It seems to work well enough, however my system log cycles errors until the drive/partition is properly mounted. Any ideas on a better method?

Systems ship with the minimum needed to boot, and not much else.
You don't have a choice on what type of RAM to use, but prices have climbed down a lot in the two years since the introduction of Mac Pro.
http://support.apple.com/kb/SP11
http://docs.info.apple.com/article.html?artnum=304235
And to get an indication of how much memory you are using
http://docs.info.apple.com/article.html?artnum=107918
http://eshop.macsales.com/shop/memory/Mac-Pro-Memory

Fusion Drive & Swap files

From time to time on my new Mac Mini with 1 TB Fusion Drive, I am getting the following error: "Your Mac OS X startup disk has no more space available for application memory."
This would indicate an issue with being able to write swap files/virtual memory. If I understand how the Fusion Drive works, the virtual memory is stored on the 128 GB SSD portion. The SSD is full, considering I have 650 GB free on the 1.128 TB Fusion Drive.
Seems like a CoreStorage issue, as it's apparently not leaving enough space on the SSD for the swap files after the computer has been run for a while. I have 16 GB RAM in the Mini.
Restarting the computer solves the issue, although I often use the Mini in remote sessions and when this error comes up, performance on the Mini tends to be so sluggish that sometimes remote connections time out or drop, making it hard to even be able to restart the computer.

Your problem is excessive swapping of data between physical memory and virtual memory.
That can happen for two reasons:
You have a long-running process with a memory leak (i.e., a bug), or
You don't have enough memory installed for your usage pattern.
Tracking down a memory leak can be difficult, and it may come down to a process of elimination. In Activity Monitor, select All Processes from the menu in the toolbar, if not already selected. Click the heading of the Real Mem column in the process table twice to sort the table with the highest value at the top. If you don't see that column, select
View ▹ Columns ▹ Real Memory
from the menu bar.
If one process (excluding "kernel_task") is using much more memory than all the others, that could be an indication of a leak. A better indication would be a process that continually grabs more and more memory over time without ever releasing it.
If you don't have an obvious memory leak, your options are to install more memory (if possible) or to run fewer programs simultaneously.
The next suggestion is only for users familiar with the shell. For a more precise, but potentially misleading, test, run the following command:
sudo leaks -nocontext -nostacks process | grep total
where process is the name of a process you suspect of leaking memory. Almost every process will leak some memory; the question is how much, and especially how much the leak increases with time. I can’t be more specific. See the leaks(1) man page and the Apple developer documentation for details:
Memory Usage Performance Guidelines: About the Virtual Memory System

My MacBook (late 2009 Mac OS X Lion 10.7.5 (11G63) often runs VERY slow...beach ball of death frequently. My page ins (5.29GB), page outs (5.64BG), and swap files (10GB) seem extremely high in comparison to most other discussions in here. HELP!!??

My MacBook (late 2009 Mac OS X Lion 10.7.5 (11G63) often runs VERY slow...beach ball of death frequently. My page ins (3.29GB), page outs (5.64BG), and swap files (10GB) seem extremely high in comparison to most other discussions in here. I don't know how to copy the pie chart so it shows on here but here's what it says right now:
Free - 176 MB
Wired - 592MB
Active - 843MB
Inactive - 432MB
Used - 1.82 GB
VM size - 198GB
The page ins and page outs have 0 bytes/sec in the parenthesis even though the numbers are so high.
Any help anyone could provide would be greatly appreciated!!!

You difinately need more ram. 2gb is the bare minimum to run just the Lion OS, anything extra will slow your Mac to a crawl. Upgrade to 8gb from either Crucial http://www.crucial.com/ or OWC http://eshop.macsales.com/
And you will be a happy camper!

SL Startup Disk filling up with Swap Files

I installed SL on an erased USB drive to see if all my applications are supported before installing on the internal start up disk. It ran fine, but after a few hours, SL had created about 40 swap files, filling up the drive. During the time I was testing SL, I launched each of my applications and updated those that needed it, but can't think of anything unusual -- no forced shut downs, quits, etc.
Anyone seen this or have any ideas on what's going on?

Hi again,
Yes, zillions of these files, I think they're accumulate every 3 seconds on my computer...
I have no idea which way to go...all of my data is backed up, so I'm not so worried about losing data...whichever way you think is best!
Here's about a page of those filenames from typing in ls private/var/tmp
00002090889b5 000056d032d47
00002090bf44f 000056d1742e2
0000209205d75 000056d1b55e6
000020923c8b4 000056d2f2a8c
0000209376f7b 000056d340509
00002093af4b5 000056d47d318
00002094e9b8e 000056d4c0632
000020952cb9d 000056d60c68a
0000209666d1f 000056d64ebbb
000020969d726 000056d78cd28
00002097d9121 000056d7ccf94
000020981df49 000056d917549
000020995a84b 000056d956e76
00002099928a8 000056da99f25
0000209acd0de 000056dade080
0000209b0fe58 000056dc27586
0000209c4a610 000056dc69994
0000209c80e10 000056dda71ef
0000209dbc646 000056dde9796
0000209df3790 000056df3a1e8
0000209f39542 000056df7e9b9
0000209f7111a 000056e0bda40
000020a0ab2b8 000056e11056d
000020a0e23bb 000056e24dc07
000020a2286c6 000056e28ca59
000020a25f17c 000056e3c99a2
000020a39ad3d 000056e415a3b
000020a3d18b6 000056e553fd8
000020a517bb7 000056e593e92
000020a54fe0c 000056e6daa3c
000020a689e9d 000056e72a2d2
000020a6c0c6a 000056e866fc5
000020a806fc2 000056e8a75ba
000020a83d6f9 000056e9e4123
000020a9789bf 000056ea30062
000020a9af25d 000056eb73924
000020aae9766 000056ebb3652
000020ab2c762 000056ecf0824
000020ac6baf9 000056ed3c4bf
000020aca3334 000056ee79574
000020addd22a 000056eebef4f
000020ae2172e 000056f012509
000020af5bc98 000056f0559a7
000020af92600 000056f1930dd
000020b0cdf81 000056f1d7494
000020b110b6a 000056f32bcdc
000020b24aa33 000056f36ab1b
000020b28283d 000056f4a7c7f

Swap file creation

Hi all ,
i am getting the following error when trying to add a swap file created in solaris 8 branded zone
bash-2.03# mv swapf test
bash-2.03# ls -l
total 1
-rw------- 1 root other 104857600 Apr 16 11:16 test
bash-2.03# swap -a /oradata/test
"/oradata/test" is not valid for swapping.
It must be a block device or a regular file with the
"save user text on execution" bit set.
bash-2.03#
Any idea why is this not possible this way?

Ok, then you just need to turn on the sticky bit. Add a leading '1' to the normal numeric attributes like so:
# chmod 1600 test
You should then be able to add the file as a swap file.

Large swap file (900MB), but no pageouts

My MacBook Air 13" with 4GB of RAM accumulates a large swap file over time, but pageouts are 0 (page ins: 1.1million). Anyone know why? Is it possible to see which process/application currently have pages stored in the swap file?

Sorry to dig this old thread up, but I am seeing an identical behavior to the original poster, and I just wanted to say—you did an excellent job of explaining how page ins can be very large with no pageouts, but I don't think this explains the real mystery, which is that there is a large amount of swap space, and a large amount the system says is used, but there are no page outs. You have not explained how a swap file gan grow in usage with no page outs, and if I understand things correctly, this should not be possible.
I'm having the same issue on my new MacBook Pro with Retina display. I have 16GB of RAM and for the most part I don't use more than 4-6GB of that—I bought it for the occasional times I need to do a lot of VM testing, but I haven't needed to do that yet. I consistently see my swap usage grow to be as large as 2-3GB with a total size for all the swapfiles in /var/vm being 3-4GB.
I don't need the space, and the system isn't slow or anything. I just want to know how this is possible. I have been using Mac OS X for 10 years now, and working on linux servers for 5 years or so. I've never seen swap usage be more than 0KB when there are no page outs.
I've attached some screenshots of what I am seeing:
Screen capture from Activity Monitor.
Screen capture from Terminal executing 'du -hsc /var/vm/swapfile*' to tally the total size of the swapfiles.
I should note that it tends to take a day or two of use to start to see this, in a series of sleep cycles here and there. I put my laptop to sleep at night as well as to and from work, etc. It probably sleeps/wakes 5-7 times a day in all. I tend to notice that the usage creeps up, starting atound 50 MB, then I will notice it being a few hundred some time later. It really makes me wonder if this has to do with some kind of discrete vs. dedicated graphics switching or something, perhaps a very low level operation that is somehow avoiding getting counted by the system's resource tracking facilities. I have no idea, but I would love it if there were someone out there who could explain it or point me in the right direction.
Thanks for your time.

Leopard swap file options

hi,
Back in Panther days you could force the swap file location but it got mucked up and frightfully complicated in Tiger. I have ram to spare. Can you force the OS to ether:
A; never use a Swap file(I have 12 gb soon to be 16 GB EEC ram) or;
B; use a ram disk like you can do in Photoshop
C: Send it to a specific partition if it insists on not noticing it never runs out of ram.
That last part has always bugged me. I always ran Tiger on this machine previously and it was annoying seeing all that free ram at thje same time watching the Os merrily paging out chunks of itself.
So, in terms of preference, It would be nice to have a terminal command(bootup script that would forbid the OS from ever paging out anything. I am so far away from saturating the bus it is not even funny. I have watched it Boinc on all 4 processors and still have 4 gb of Ram sitting idle.

It is time for Apple to fix that performance whole. Why sell machines that have max out slots with far more memory then the machine can ever use even at full tilt.
They have made great strides in the memory use department with the Mac Pro.
OS X only uses a set amount of memory, and then goes to virtual memory.
A lot of this is to allow other applications to use/have access to the RAM, rather than having the OS hogging it all.
There is no user control for this, short of hacking the memory allocation process within the BSD.
Just keep plenty of free space on the boot drive for the OS to run properly, and have a second scratch drive for PS and pro apps to use to run properly.

[Solved] Do I need a swap partition /swap file?

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