Software :: Didn't Use Swap Memory In CentOS 5.4
Feb 27, 2010
I found out that my CentOS 5.4 linux does not use any swap memory! here is the #top output:
top - 10:02:49 up 27 min, 5 users, load average: 4.22, 3.45, 2.24
Tasks: 173 total, 4 running, 166 sleeping, 0 stopped, 3 zombie
Cpu(s): 71.1%us, 26.1%sy, 0.0%ni, 0.2%id, 0.0%wa, 2.7%hi, 0.0%si, 0.0%st
Mem: 3081388k total, 1729216k used, 1352172k free, 69544k buffers
Swap: 5140760k total, 0k used, 5140760k free, 865316k cached
I wonder why swap memory is not used! I also face auto-restart issue while running few tasks. Does it relate to the swap memory?
uanme -r -> 2.6.18-164.el5
I remember that my i have allocated about 5G for swap memory. However I put it into different partition and far away from root partition due to diskspace partition. Does it matter?
I do not know how to show the swap memory partition or partition map over here.
here is the mount output
/dev/sda2 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
[Code]....
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Aug 16, 2010
RAM for older machines like I use is fairly cheap these days. But flash memory is just as cheap or cheaper. So I'd like to ask about the feasibility of expanding my system's memory using flash memory. And about whether creating a partition for swap on the flash memory, or whether a swap file on the flash device, is the better way to go.
By flash memory I have in mind mainly USB sticks or what are sometimes called "pen drives." But I do also have CF and SD cards that, with the proper cheap adapter (one of which I already own for adapting CF) could be used to create extra swap space. So, what is the current consensus on the feasibility/advisability of using flash memory for swap? I've read about the limited write cycles of flash being an argument against using it for swap. But recent reading indicates to me that the limited write cycles problem applies mostly to older, smaller-capacity flash memory. Some will come out and say that, for larger-capacity flash memory, the life of the device is likely to exceed the amount of time your current computer will be useful (I think I've seen estimates in the range of 3-4 years life--minimum--for newer, higher-capacity flash memory).
A more persuasive argument I've heard against using flash memory for swap is that access times for these devices can be much slower than SATA, and maybe even IDE, hard drives. That would certainly dictate against using flash memory for swap.
So, how about some input on this issue? Anyone using flash memory for swap? If so, what kind (e.g., usb stick or SD/CF)? Are you using a swap file or a swap partition? How's system performance? Likewise, has anyone had flash-memory-used-as-swap die on them? The consequences would undoubtedly be dire. Also, has anyone measured flash memory access times to confirm or refute claims about slow access times? Are some types of flash memory better/worse than others in terms of access times?
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Sep 12, 2010
I've an 8GB swap (I know, overkill, but I don't have space issues, and I'd rather have too much instead of too less). The problem is that my physical memory fills up, and the system crashes, but swap usage is ALWAYS 0%
Mem: 8060580k total, 5193436k used, 2867144k free, 1013788k buffers
Swap: 8388604k total, 0k used, 8388604k free, 2262112k cached
Setting aside the fact that I can't trace why memory usage goes up to 8GB with just firefox/terminals/pidgin, why isn't my swap EVER used?
Also, if I run
Code:
# top
2301 hugo 20 0 1887m 665m 38m S 19.9 8.5 267:38.63 firefox-bin
1811 root 20 0 166m 67m 10m S 10.8 0.9 128:04.59 X
1973 hugo 20 0 306m 78m 16m S 0.8 1.0 42:30.04 compiz
2024 hugo 20 0 487m 13m 8836 S 0.2 0.2 2:14.73 Terminal
1980 hugo 20 0 333m 7228 5492 S 0.1 0.1 0:54.49 lxpanel
7048 hugo 20 0 15016 1168 820 R 0.1 0.0 0:00.03 top
(The rest are all "0 0 0 0 S 0.0 0.0")
If add up all of the RES columns, I get <1GB. If I add all the VIRT column, I get about 3GB. Where's the other 2GB being used? This goes up all the way to 8GB, without being able to add up where my memory's going.
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Feb 23, 2011
There are plenty of tools for umounting/mounting/automounting usb flash/pen drives/dongles/hard drives. There's the Device Notifier on kde 4, for example.
But what about other devices like headphones, mice, keyboards, modems, etc? A tool for doing this would be very handy.
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Sep 12, 2010
When we want to setup a linux system, there is a common a suggestion like set the swap space as twice as big than your physical memory, I want to know why do we need this and how is this suggestion come from?
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Apr 20, 2011
I used Gparted to resize the swap area, and doing so changed the UUID so now the swap memory is not activated automatically and hibernation is also inactive. i got some info about this in a previous thread, which became inactive, and could not fix the problem.the output of sudo blkid is:Quote:
sudo blkid
/dev/sda1: UUID="8bcd1749-f82d-4d4a-967d-ee8a3583e8e2" TYPE="ext4"
/dev/sda5: UUID="e02d4dcf-a064-4e6b-a014-a0d9db55f00f" TYPE="swap"
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Jul 14, 2011
I did a standard install of Ubuntu 9.10, then upgraded to 10.04 LTS. Whenever I run htop I get:CPU [~3.8%] Mem [100/244MB] Swp [87/713MB]And free -mMem- total:244 used:214 free:29Swap- total:713 used:86 free:626It seems like I should be using allocating more memory to swap. I should be using more swap, or if this looks normal
B. If so, how do I re allocate more memory to swap?I am new to linux and still trying to figure out a lot of things.
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Jun 1, 2011
I came across this article, which I found to be very interesting and thought share it with you all.
Graphics CardMemory as swap space or RAM disk.
[URL]
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Oct 24, 2010
I have a system with 2G of memory and swap memory of 4G.
This is the output from :
PHP Code:
How could they do to the memory cache to be used as much? Because, occasionally, swap is used and note that the system could use the memory cache does not swap ...
Slackware current 64 multilib.
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Jun 20, 2010
Why linux uses swap space, even if there are free physical memory available.
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Jun 24, 2009
i have a RAM of 1 Gb & swap of 1Gb with fedora11 installed, initially in RAM programme memory uses around 300 Mb & cache uses 600-700 Mb , but after some time it starts using swap memory though my programme memory is still around 300 mb, it keeps on increasing swap memory as a result my system keeps on slowing down & finally when swap memory is 100% system almost stops responding but programme memory is still around 300mb.
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Apr 7, 2010
I run a memory-hungry process (mkcromfs) which consumes more memory than I have physical memory on my latop, so it is paging and swappin and thrashing all the time and loadavg is about 2 (compcache is already in use with usual swap partition as well), but slowly moving forward (Although I afraid it will finally try to allocate >2GB and crash draining 2 days of thrashing).
When I want to use the laptop for something else, I stop the process, start X server, firefox and other programs. The problem is that when I start Firefox the loadavg jumps to 10 and the system becomes almost unresponsive at all (long time to turn on/off caps lock, slow mouse cursor position updates, slow switching from X server to Linux console, slow login).
The stopped mkcromfs still holds a lot of memory (464.8 MiB and slowly falling) and moves it to swap only when more memory is needed for some other program, which results in a great slowdown.
How to tell the Linux to swap out this process entirely (e.g. I'm not intending to resume it in short term), possibly waking from swap other data? Also it will be useful to be able to specify the exact swap device to swap the given process out (for example, mkcromfs's memory is useless in ramzswap).
Update: Now I just write a 400-600M of data from /dev/erandom to tmpfs and it makes mkcromfs to shrink. Is there more proper way?
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Dec 10, 2010
Nagios had alerted me that the server had a very high load average exceeding the critical level (17+), when logging onto the server I found that all 4GB of the swap was in use despite the fact that there was 15GB+ of free memory (and that's not even including memory from cache and buffers!) Because it seems all heavily used pages were being stored in swap, the I/O wait on the server became very high, and 4 kswapd daemons were taking up nearly 100% available CPU. This did coincide with an error reported by Bacula during a backup job while changing to a bad tape...
From /var/log/bacula.log:
Code:
10-Dec 02:11 bacula-sd JobId 1898: End of medium on Volume "4097" Bytes=434,170,000,000 Blocks=217,084 at 10-Dec-2010 02:11.
10-Dec 02:11 bacula-sd JobId 1898: 3307 Issuing autochanger "unload slot 4097, drive 0" command.
10-Dec 02:12 bacula-sd JobId 1898: 3301 Issuing autochanger "loaded? drive 0" command.
10-Dec 02:12 bacula-sd JobId 1898: 3302 Autochanger "loaded? drive 0", result: nothing loaded.
10-Dec 02:12 bacula-sd JobId 1898: 3304 Issuing autochanger "load slot 4096, drive 0" command.
10-Dec 02:13 bacula-sd JobId 1898: 3305 Autochanger "load slot 4096, drive 0", status is OK.
10-Dec 02:13 bacula-sd JobId 1898: Volume "4096" previously written, moving to end of data.
10-Dec 03:51 bacula-sd JobId 1898: Error: Unable to position to end of data on device "Tape-1" (/dev/IBMtape0n): ERR=dev.c:1384 read e
rror on "Tape-1" (/dev/IBMtape0n). ERR=Input/output error.
10-Dec 03:51 bacula-sd JobId 1898: Marking Volume "4096" in Error in Catalog.
10-Dec 03:51 bacula-sd JobId 1898: 3307 Issuing autochanger "unload slot 4096, drive 0" command.
10-Dec 03:58 bacula-sd JobId 1898: 3301 Issuing autochanger "loaded? drive 0" command.
10-Dec 03:58 bacula-sd JobId 1898: 3302 Autochanger "loaded? drive 0", result: nothing loaded.
10-Dec 03:58 bacula-sd JobId 1898: 3304 Issuing autochanger "load slot 4098, drive 0" command.
10-Dec 03:58 bacula-sd JobId 1898: 3305 Autochanger "load slot 4098, drive 0", status is OK.
10-Dec 03:59 bacula-sd JobId 1898: Wrote label to prelabeled Volume "4098" on device "Tape-1" (/dev/IBMtape0n)
10-Dec 03:59 bacula-sd JobId 1898: New volume "4098" mounted on device "Tape-1" (/dev/IBMtape0n) at 10-Dec-2010 03:59.
At the same time, these messages starting occuring in /var/log/messages:
Code:
Dec 10 03:51:47 07 kernel: Mem-info:
Dec 10 03:51:47 07 kernel: Node 0 DMA per-cpu:
Dec 10 03:51:47 07 kernel: cpu 0 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 0 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 1 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 1 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 2 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 2 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 3 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 3 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 4 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 4 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 5 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 5 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 6 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 6 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 7 hot: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: cpu 7 cold: high 0, batch 1 used:0
Dec 10 03:51:47 07 kernel: Node 0 DMA32 per-cpu:
Dec 10 03:51:47 07 kernel: cpu 0 hot: high 186, batch 31 used:162
Dec 10 03:51:47 07 kernel: cpu 0 cold: high 62, batch 15 used:48
Dec 10 03:51:47 07 kernel: cpu 1 hot: high 186, batch 31 used:0
Dec 10 03:51:47 07 kernel: cpu 1 cold: high 62, batch 15 used:0
Dec 10 03:51:47 07 kernel: cpu 2 hot: high 186, batch 31 used:0
Dec 10 03:51:47 07 kernel: cpu 2 cold: high 62, batch 15 used:0
Dec 10 03:51:47 07 kernel: cpu 3 hot: high 186, batch 31 used:18
Dec 10 03:51:47 07 kernel: cpu 3 cold: high 62, batch 15 used:0
Dec 10 03:51:47 07 kernel: cpu 4 hot: high 186, batch 31 used:159
Dec 10 03:51:47 07 kernel: cpu 4 cold: high 62, batch 15 used:56
...
Dec 10 03:51:47 07 kernel: Node 3 HighMem per-cpu: empty
Dec 10 03:51:47 07 kernel: Free pages: 732052kB (0kB HighMem)
Dec 10 03:51:47 07 kernel: Active:4232128 inactive:3071288 dirty:158210 writeback:0 unstable:0 free:183320 slab:256840 mapped-file:289545 mapped-anon:3805487 pagetables:13063
Dec 10 03:51:47 07 kernel: Node 0 DMA free:10796kB min:4kB low:4kB high:4kB active:0kB inactive:0kB present:10356kB pages_scanned:0 all_unreclaimable? yes
Dec 10 03:51:47 07 kernel: lowmem_reserve[]: 0 3512 9067 9067
Dec 10 03:51:47 07 kernel: Node 0 DMA32 free:213332kB min:2500kB low:3124kB high:3748kB active:1794108kB inactive:1463220kB present:3596296kB pages_scanned:64 all_unreclaimable? no
Dec 10 03:51:47 07 kernel: lowmem_reserve[]: 0 0 5555 5555
Dec 10 03:51:47 07 kernel: Node 0 Normal free:41028kB min:3952kB low:4940kB high:5928kB active:3409444kB inactive:1471120kB present:5688320kB pages_scanned:0 all_unreclaimable? no
Dec 10 03:51:47 07 kernel: lowmem_reserve[]: 0 0 0 0
Dec 10 03:51:47 07 kernel: Node 0 HighMem free:0kB min:128kB low:128kB high:128kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no
Dec 10 03:51:47 07 kernel: lowmem_reserve[]: 0 0 0 0
Dec 10 03:51:47 07 kernel: Node 1 DMA free:0kB min:0kB low:0kB high:0kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no
...
Well to cut a long story short, I fixed the problem by disabling the swap partition with 'swapoff'. After about 30 mins all the swap was freed and the server went back to normal. I don't dare reactivate the swap partition and unfortunately as this is a live server which currently has no fail over, I can't reboot either
Server Spec:
4 * Dual-Core AMD Opteron(tm) Processor 8214
32GB DDR2 ECC RAM
RHEL 5.5, 2.6.18-194.11.3.el5 SMP x86_64
Running many KVM VMs (All CentOS x64) and kksmd is used.
bacula-dir Version: 5.0.0
IBM Tape Drive using lin_tape module version 1.34.0 according to modinfo
And before anybody asks
# sysctl vm.swappiness
vm.swappiness = 10
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Feb 2, 2011
In our cluster, both the server and worker had been gone to swap and the performance is extremely slow. Although currently the memory is free but I don't know why the in the swap area is still being there and ubuntu doesn't move them to the memory and empty the swap.
On the other hand, when I run
Code:
sudo swapoff -a
on the server it says:
Code:
mahmood@server:~$ sudo swapoff -a
[Code]....
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Apr 6, 2010
clarify me with ulimit output and memory limit?
ulimit -a output:
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) 1572864
[code]...
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Jan 22, 2010
Just installed CentOS 5.4, had no problems until the first time it tried to login, where the keyboard didn't work. There are bugs logged on both the CentOS site, and the Red Hat site, but nobody seems to have a definitive solution (other than buy a USB keyboard). Bearing in mind that the machine in question is not hooked up to a network (i.e. no internet updates), is there a way to resolve this issue?
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Jan 28, 2010
I am trying to see if I can swap out our 150+ Novell Suse Linux Enterprise Server for CentOS. From my initial thoughts I can. I am however running into an issue with the firstboot. Currently, we use firstboot on Suse with our base image. We created an image which we deploy and then firstboot runs our necessary scripts to configure the networking and office specific settings. I want to test this out but when I search for the firstboot.xml file I can't find it. I need to modify the config file and change the way the firstboot runs. Is this possible with CentOS?
I am also wondering if anyone is using Novell ZenWorks Linux Management to manage their CentOS instances or if you are using something else I would like to hear what tool you're using. I would need the ability to deploy patch/ security updates and make occasionally changes to files, not very often though.
Just a brief run down of what the server(s) will be doing. Their primary purpose is to provide caching via squid and the use of the browser for new hires until they get their notebooks. The browser runs Java and flash and the ability to print is also necessary. Pretty basic stuff so I am looking at CentOS cause the forums look very active!
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May 25, 2010
I was able to do on Debian and Ubuntu Servers X applications running on remote servers where I was able to login via SSH. Tried the same with CentOS did not worked. in /etc/ssh/sshd_config
[Code]....
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May 9, 2010
I have 2G of physical memory and 1G of memory swap. Very rarely the memory swap is used and when usage is around 1% while, then gets a lot of free physical memory...My question is:It is possible to "clean up" the memory swap. Or better still (I think). It is possible to spendphysical memory for data that is in memory swap?
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Oct 14, 2009
I have problems setting up a (2 server) cluster. I get the following messages in syslog:
Oct 14 13:02:21 korzel ccsd[7823]: Starting ccsd 2.0.115:
Oct 14 13:02:21 korzel ccsd[7823]: Built: Sep 3 2009 23:26:21
Oct 14 13:02:21 korzel ccsd[7823]: Copyright (C) Red Hat, Inc. 2004 All rights reserved.
Oct 14 13:02:21 korzel ccsd[7823]: cluster.conf (cluster name = cl_vpanel, version = 1) found.
[code]....
Tried with the "basic" hosts file as well, eg with only the localhost lines in it. Both server run centos 5.3, up-to-date.There is no real error anywhere which might explain WHY aisexec daemon won't start. When i start openais manually (/etc/init.d/openais start) it starts without any errors.
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Apr 22, 2010
I've a database-server (IBM x3650 M2) with about 3 TB Data on SAN (Hitachi) with lvm top of softraid (RAID1) based on multipath (2 SAN-boxes in different buildings). After booting the server, multipath starts, but no md starts the mirror. The same configuration with SLES 10 works.
cat /proc/mdstat
Personalities : [raid1]
md13 : active raid1 dm-17[1] dm-14[0]
[code]....
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Oct 19, 2010
I install a Bind 9 with chroot in Centos 5, but the issue is the Reverse Name Resolution Zone File didn't create by default like other zone files, so i look into /var/named directory i don't find the reverse name resolution zone file even if i add this zone on named.conf
zone "1.168.192.in-addr.arpa" IN {
type master;
file "1.168.192.testsip.com.zone";
allow-update { key "rndckey"; };
notify yes;
};
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Dec 20, 2010
I am a linux newbie, I spent more than 3 days trying to set up the drivers for my Intersil Prism 2 Wi-Fi adapter on CentOS 5.5. While trying to Make the driver source I receive errors of missing libraries. Is the hostap driver included in the Centos Kernel? I tried with insmod hostap but it didn't work..? Is there a kernel patch with the hostap drivers? I will be glad if someone can give me ideas or directions for setting up the driver properly.
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Aug 27, 2010
I just ran into a weird problem with a CentOS 5.5 64-bit server running VirtualBox 3.2.8 (I would run Vmware Server 2.0.2 if not for the well known fact that Vmware doesn't care about its Server line anymore and it doesn't run on CentOS > 5.3 without major splits). I currently have two guests in that VirtualBox setup, a CentOS 5.5 64-bit and a Fedora 13 64-bit. The CentOS 5.5 guest shows less memory available than configured. If, for example, I give the virtual machine 512MB of memory the guest OS only recognizes 380MB. If I give it 768MB it only recognizes 637MB, and so on. I don't have that problem on the Fedora guest - 1024MB configured, 1024MB available.
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Jun 17, 2009
I have a dual xeon e5420 server w/ 16GB ram running 5.3 x64 that I was trying to partition out in the following configuration:
250GB on / (root)
4.2TB on /home
50GB on /tmp
2GB on swap
The issue is that no matter what size I set the swap space to in anaconda if always shows 8GB when I "df -h". I've tried setting it to 2GB 1GB and 512MB all with the same result.
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Nov 24, 2009
I am trying to increase my swap size because it seems to be getting full and making my server lock up.
I've tried this: [URL]
But all I get is this:
# lvm lvresize /dev/VolGroup00/LogVol01 -L +8000mb
Extending logical volume LogVol01 to 9.75 GB
Insufficient free space: 250 extents needed, but only 0 available
vgdisplay gives me:
[Code]....
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Jan 24, 2011
Howto install CentOS 5.5 as a second OS to share the same SWAP Partition with other linux, for example Debian?
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Mar 20, 2011
How to add swap space?
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May 10, 2009
Are there any general recommendations on skipping creation of swap partition on servers? If I am sure that server will be ok with it's RAM is there any benefit in skipping swap partition creation or making it the least size possible other than saving disk space?
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Sep 22, 2010
I had Oracle install on my machine and there were some ASM partitions. after uninstall of oracle some how it removed the swap space and now is showing:
[Code]...
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