Linux divides its physical RAM (random access memory) into chucks of memory called pages. Swapping is the process whereby a page of memory is copied to the preconfigured space on the hard disk, called swap space, to free up that page of memory. The combined sizes of the physical memory(RAM) and the ...

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159 views

On a virtual Linux system where storage is on network what's the point of the swap file? [closed]

The Linux servers are running on some VMWare ESX systems (guessing, I'm just user). These systems don't have the disks directly attached: they perform everything on a virtual disk that is actually a ...
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3answers
1k views

With Xen, when is Swap used?

I have a 512MB Xen VPS with 1024MB Swap. When I SSH into it and type "free -m", it shows I have around 50MB free memory. I had recently downgraded from a 1024MB plan because I didn't need the ...
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1answer
791 views

LVM cannot detect my swap or '/' volume group but why is the swap still present

i have a server (hp x86 blade running OEL/RHEL5) that has a faulty lvm filter configured in lvm.conf filter = ["a|^/dev/emcpower.*|", "r/.*/"] we also use cciss devices so there should have been an ...
1
vote
3answers
761 views

I/O rate and CPU Eating up Server making terribly slow site

My server (Ubuntu 10.04 Lucid LAMP Stack) on linode (1024MB ram, 40 GB storage, 400 GB Transfer) is loading terribly slow. My site (WordPress) is relatively small (1.5 Gigs of mysql) and gets around ...
3
votes
1answer
231 views

Force process pages to get unswapped

I started 4 processes doing heavy computations. The machine has 4 full cores, and each process is single-threaded, so they don't compete for CPU. However I realized that they require more memory than ...
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2answers
4k views

Ubuntu Linux: Process swap memory and memory usage

My Ubuntu eats more memory than the task manager is showing: sudo ps -e --format rss | awk 'BEGIN{c=0} {c+=$1} END{print c/1024}' 2750.29 free -m total used free ...
5
votes
1answer
344 views

Mysterious swap usage on EC2

We're in the middle of a project to move our infrastructure from a co-lo situation into Amazon EC2 and we've noticed some weird memory characteristics of the processes in our setup. Without going into ...
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1answer
2k views

Centos server not using SWAP properly and getting OOM

Recently I've been having some serious memory issues with my server. Just the other day, my server became completely unresponsive, and oom-killer started killing services at random (httpd, php, etc). ...
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5answers
2k views

What happens if you run out of RAM and swap?

Running MySQL on a box with 32 gigs of RAM. Swap is 99% full, and there is about 200 MB of RAM free. MySQL is the culprit of course. What happens when both RAM and swap are completely filled? Thanks! ...
3
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1answer
487 views

Apache is not using SWAP and it's reporting page allocation failure

Check the logs: httpd: page allocation failure. order:4, mode:0xd0 Call Trace: [<ffffffff8000f696>] __alloc_pages+0x2ef/0x308 [<ffffffff80017a40>] cache_grow+0x139/0x3c7 ...
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vote
2answers
321 views

swap partition alignment: is there any benefit?

On some of my Linux servers, the swap partition is misaligned. I understand how partition alignment affects performance on mounted file systems with 4k block sizes, but I am unsure if the same ...
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2answers
1k views

How to make Swap work? CENTOS 5.7

I've got a Centos 5.7 running Magento with nginx. I also got there 10GB of Swap. But the os never use it. How can i make it work?
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2answers
132 views

Swap on Ubuntu and CentOS

I have two questions, which is both related to a swap partition or file. Is it possible to install either Ubuntu or CentOS without a swap configured, without tinkering? Live CDs like Ubuntu, is ...
2
votes
1answer
808 views

Server refuses to use swap partition

We are running a server with 23 cores (cpuinfo shows 22 as the highest process number) and 66 Gig RAM. The development team here is running some apps, which hogs memory. I have observered that: 1. ...
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1answer
131 views

Kill or revive a process based on system memory usage

Consider a system with limited memory, like a smallish VPS. Suppose there are a handful of processes that need to stay alive, and one process "P" that would be nice to have around, but is not ...
6
votes
1answer
7k views

How to free swap without rebooting (to avoid hourly alert emails)?

I get alert emails whenever swap usage is at 100%. In my case, swap usage doesn't reduce later on (even though memory is free) so I get an alert email every hour. How can I reduce swap usage without ...
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8answers
11k views

Should I completely turn off swap for linux webserver?

Recently my friend told me that it is a good idea to turn off swap on linux webservers with enough memory. My server has 12 GB and currently uses 4GB (not counting cache and buffers) under peak load. ...
8
votes
3answers
18k views

How to increase swap size?

Recently, I put more ram into my server and now I have got a total of 24GB of RAM. Originally, I setup the OS to have a 2GB swap size. /dev/sdc1 1 281 2257101 82 Linux ...
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votes
3answers
1k views

top reports swap at 100%, free memory available

On RedHat 5 servers, we see top reporting swap has 0k free. vmstat shows the same amount of swap used, but no paging. We kill our only app, and top still reports 100% of swap used. If we reboot, ...
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3answers
292 views

Socket and Swap Space

I have a system that is running out of memory and has a lot of open connections. but my swap space is not being used up that much. Can socket/socket file descriptors use swap space? This is for a ...
2
votes
1answer
362 views

Windows Server: Prevent process swapping/paging

Is there a possibility to prevent swapping for a single process? This process is an in-memory-database and should not be moved to virtual ram. all other processes should still be swap-able. I ...
2
votes
2answers
353 views

Should swap space be in a logical volume, or directly on disk?

What are the benefits of putting swap into a logical volume over using direct disk access? For example, with a fresh, default install of RHEL5 or 6, a volume group is created on the default disk ...
2
votes
1answer
273 views

Ubuntu Swap on EC2 with an EBS root

Running Ubuntu 11.04(natty) on an EC2 micro instance. Setup 1gb swap file at /mnt/swap. Works fine until I reboot and then the swap is not active. I can activate it manually using swapon -a, but my ...
4
votes
1answer
10k views

why is kswapd using high CPU on an idle system?

I have an idle Linux centOS system and yet kswapd is using 100% cpu. All I have running is a single bash session with top running.... I have 32G RAM and yet kswapd is constantly using 100% cpu for ...
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votes
3answers
29k views

How do I tell what process is causing kswapd to be in use?

I see kswapd using 100% CPU... how can I tell on which process's behalf kswapd is being used so much?
8
votes
1answer
643 views

Create swap file on a running Linux machine

Our company web sites have just been moved from a shared host to a VDS, as the hosting company plans on retiring the less than completely reliable shared hosting server(s). The VDS only has 256MB of ...
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votes
4answers
4k views

How to create a randomly keyed, encrypted swap partition, referring to it “by-uuid”, on Debian?

It is sensible that if you have any sort of block device encryption implemented on your GNU/Linux system, to encrypt your swap partition too, as any decrypted data may be written in cleartext at any ...
2
votes
2answers
127 views

Tuning windows virtual memory/paging for a specific workload

I have a specific ram-intensive program I run which slows down my entire system for hours after each run - does the Windows NT 6.0/6.1 kernel have any tunables to encourage processes' working sets to ...
1
vote
1answer
194 views

Reasonable memory limit alarm for 2GB machine running RHEL5 OS

We have a bunch of servers with the below configuration: Dual Core single processor 2GHz with 1 MB Cache. Swap is enabled with 1GB limit Memory - 2GB OS - RHEL5.3 64bit One of our alarms is ...
9
votes
2answers
5k views

Why does Windows 2008 use swap before the memory is full?

I administer a Windows 2008 server (well, on Amazon EC2) running IIS and a .NET4 Web app. I got a memory alert the other day and went and looked, and sure enough the process memory had grown over ...
3
votes
1answer
435 views

How does the Windows /3gb switch relate to physical RAM?

I have a 32-bit Windows server with 4 GB of RAM. From reading various articles on the web, I reached the understanding that enabling the /3GB switch in boot.ini would mean that of my 4 GB of RAM, 3 ...
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votes
6answers
5k views

What and why is my swap space used under linux

on my linux system I get these stats from top: Tasks: 155 total, 1 running, 153 sleeping, 0 stopped, 1 zombie Cpu(s): 1.5%us, 0.3%sy, 0.0%ni, 97.4%id, 0.7%wa, 0.0%hi, 0.0%si, 0.0%st Mem: ...
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vote
2answers
2k views

memory leak? RHEL 5.5. RSS show ok, almost no free memory left, swap used heavily

i encounter a very instresting problem, and it seems that some physical may disapper quietly. i am very puzzled, so if anyone could give some help, I would be very appreciated. here is my top show: ...
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votes
1answer
974 views

SWAP CRITICAL - 100% free (0 MB out of 0 MB)?

ANy ideas how to address this issue ....I am on ubuntu 10.04 on amazon ec2 here is the image
3
votes
5answers
2k views

How to prevent going to SWAP?

We have a critical application which uses pretty much of our RAM memory. At most time the application stays in RAM, however there are some situation (e.g. when some other applications and deamons ...
0
votes
2answers
429 views

swap on dev + but get mount dev + how to swap dev anyway?

when I do the: mkswap /dev/sda3 mkswap: error: /dev/sda3 is mounted; will not make swapspace. how to perfrom mkswap anyway , David
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votes
1answer
358 views

swap never used, system freezes with high HD action when RAM is short

My system freezes quite often when run out of memory, I have 2GB and using netbeans, chrome, firefox and a few other apps this is consumed completely. Seems to me since I upgraded to ubuntu natty. ...
0
votes
4answers
4k views

linux redhat 5.4 - swap while memory is still available

This server is swapping using 100% (15G swap disk) while it still has 30G free, I've been looking arround but can't figure why this is happening, my understanding was not to use swap if memory is ...
0
votes
3answers
117 views

Paritition an LVM LV

I have an LVM logical volume (LV) and would like to create partitions within this LV to provide an ext3 partition and a swap partition. This LV would then get mounted as a disk to a virtual machine ...
4
votes
2answers
944 views

Linux: Where to put the swap file

Are there any conventions on where to put swap files on Linux? I usually just create them in /var/swapfile, but that seems a bit too high up in the hierarchy.
2
votes
2answers
916 views

Resizing swap partition (RHEL 5.x)

Following is how parted print looks like: (parted) print Model: VMware Virtual disk (scsi) Disk /dev/sda: 26.8GB Sector size ...
0
votes
2answers
449 views

Linux swap partition not recognized on reboot

When I reboot my Linux server the swap space reads 0 in top. I am running a vanilla install of CentOS 5.2 /etc/fstab looks fine from what I can tell /dev/VolGroup00/LogVol01 swap swap defaults 0 0 ...
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votes
3answers
4k views

How does putting swap space on an SSD affect performance?

This is more of a generic question I'm interested in, rather than something I'm planning to use in production. If I got, saym a 40GB SSD drive and allocated the entire drive to be swap space leaving ...
3
votes
3answers
3k views

Identifying a process that leaks memory

On a linux server (Ubuntu Lucid), my used swap keeps growing by the hour on a server, and I'm having a hard time identifying which process is growing in swap. What tool can I use to monitor this?
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vote
1answer
852 views

Problem with setting up partitions - encrypted swap partition won't mount

Here's the layout I have; I'm using Software RAID10, LVM, and Encryption: LVM VG vg0, LV main - 2.0 TB Linux device-mapper (linear) #1 2.0 TB K crypto (vg0-main_crypt) ...
0
votes
4answers
4k views

Server super slow, RAM & Swap 100% used, ClamAV problem?

My Ubuntu 10.04 server is down since this morning. When I restart it, I can use it for a couple of minutes then the RAM and Swap get full, and SSH doesn't answer. It seems ClamAV is part of the ...
2
votes
1answer
114 views

suspend process if number of hard page faults surpasses a given amount per second

Is there a way in linux to send a signal or otherwise install an handler to be called when a process surpasses a given rate of hard page faults per second? A simple sigstop would avoid many ...
3
votes
4answers
1k views

Running swap on RAID10 or RAID5?

In follow-up to this previous question (and it's excellent answer), I am curious to know if running swap on a RAID5 might not be better than on a RAID10. My thinking is that you might lose a bit on ...
0
votes
1answer
1k views

What do the output values of dstat command mean when monitoring IO?

I am monitoring the IO and SWAP usage of a process in my backup server. I executed dstat -rs 5 and this was an example output: --io/total- ----swap--- read writ| used free 92.0 57.3 |3228k 514M ...
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2answers
251 views

Moving/Adding Additional Swap Location - Redhat 5

OK, here's what's going on. I've got a RedHat 5 server with a swap partition (/dev/sda3) that's 3GB. For some reason swap memory is still being taken up on / (/dev/sda2), and fills up the drive on ...