Server :: Free Physical Memory Available Then Why Swap Space Used
Jun 20, 2010Why linux uses swap space, even if there are free physical memory available.
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General :: Why Set Swap Space Twice Big As Physical Memory
Sep 12, 2010When 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?
View 4 Replies View RelatedServer :: 100 Percent Swap Usage With Loads Of Free Memory
Dec 10, 2010Nagios 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
Slackware :: Prioritize The Use Of Physical Memory Instead Of Swap?
Oct 24, 2010I 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.
General :: Application Virtual Address Space Memory Allocation - Memory Does Not Get Free
Apr 20, 2010I am using malloc and frees a lot in my program. It shows its allocated but when i remove it doesnt show as the memory is removed(I am using the top command to view VIRT memory usage). If this continously grows what would happen to my program (Will it go out of memory?)
View 4 Replies View RelatedFedora :: Reduce Size Of Swap To Free Up Some Space
Aug 21, 2010My laptop has 2Gb of ram, 4Gb of swap, 40Gb hdd and an intel pentium 1.40GHz cpu, even when compiling stuff or maxing out everything the 4Gb of swap is never touched, with such a small hdd I'd like to reduce the swap to about 2Gb (just in case) to free up some space, does anyone know what commands/tools are available to accomplish this?
View 3 Replies View RelatedGeneral :: Mapping Kernel Virtual Address Space To Physical Memory Zones?
Nov 4, 2010As i undertsand - out of 1GB of the virtual Address space for Kernel from 3GB to 4GB of the process address space, Kernel image (code, data, bss, stack, heap) resides staring @0x0 address. Vmalloc area starts either at the end of Physical ram size or at 896M. This 896M cap is mandated to ensure that minimum of 128MB is reserved as vmalloc_reserve for vmalloc,kmap etc.
Is the understanding correct? Now trying to map Physical Zones into this 1GB address space
Initial 16MB is mapped to ZONE_DMA
16MB - 896MB is mapped to ZONE_NORMAL
896MB - 1024MB is mapped to ZONE_HIGHMEM
Does this mean that Kernel image is residing in ZONE_DMA area? Any call to vmalloc() in kernel code will return address beyond 896M? insmod of any LKM will internally invoke vmalloc() to obtain contiguous area - where will this code physically located along with rest of kernel code in ZONE_DMA or in ZONE_HIGHMEM?
Server :: Clear Cache Memory ( RHEL 5.1 ) As It Consumes Almost 100% Physical Memory?
Jan 11, 2010let me know how to clear cache memory ( RHEL 5.1 ) as it consumes almost 100% physical memory.
View 3 Replies View RelatedGeneral :: 'clear Out' All The Old/cached Crap From RAM/SWAP To Free Up Space?
Jul 21, 2010Closest analogy I can compare what I want to, is like the `sync` command, which writes out all stuff in the disk buffers, freeing the buffers.Instead of disk buffers, I want to 'clean out' my RAM and SWAP of any/all junk that's accumulated in there over the time my PC has been up. I've long wondered about this, but never asked, though I recall searching around several times..When I first boot it cold and log in, the memory usage bar on my desktop is near zero, and the swap is empty. But after a week or 2 or 3 or more of uptime, and with Firefox always running with a dozen tabs or so at any given time, I end up with all the memory full or 'filled with cached stuff', and the swap space is filled to capacity.Curiousity: I blame Firefox for leaking memory, but even if that's still the case today (historically it was) can this all be blamed on Firefox? Or what-all causes this, besides Firefox- just..Everything?
Here's current stats:
Code:
sasha@reactor: uptime
21:21:42 up 30 days, 10:07, 3 users, load average: 0.02, 0.05, 0.01
sasha@reactor: free
total used free shared buffers cached
[code]...
So, 3.8 of 4 Gib of RAM is occupied, and the 1 Gib swap space is jammed full 100%. This must slow things down to some degree, yes? I mean, the kernel does have to keep track of this, right?Of course closing all the applications doesn't make a difference (not an appreciable one anyhow) and the only way I have found to start fresh is to reboot.
General :: How To Free Up Space - Memory Insufficient Error
Apr 25, 2010When I use top to see memory usage, I have 65gb ram but only 1.3gb of it free and remaining is shown as used. When I ran my program It gives memory insufficiency error. Although no other program is using the remaining 63.7gb ram it is hold. How can I get free the unused ram?
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Mar 27, 2010Was wondering if anyone can explain briefly the relationship of "cache" and free memory in the "free" memory command.
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Jul 16, 2011i had configured the opennms but i didint able to get the disk space and memory alert by mail... and also i need a plgin gor opennms can u tell me wat plugins suit for opennmms monitoring tool ...
View 2 Replies View RelatedGeneral :: Set The Limits For Unlimited Virtual Memory With Limited Ram And Swap Space On Disk??
Apr 6, 2010clarify me with ulimit output and memory limit?
ulimit -a output:
core file size (blocks, -c) unlimited
data seg size (kbytes, -d) 1572864
[code]...
Server :: Use System Monitor Via A VNC Connection The Free Disk Space Value Is 20GB Free On The Same Volume
May 18, 2011I've got a question on free disk space. I'm currently running CentOS 5.5 on in Xenserver virtual environment. We've had an issue with disk space. My question is as follows: - from a ssh connection i run df -h this gives the value of 90% used leaving me with 9GB. If I use system monitor via a VNC connection the free disk space value is 20GB free on the same volume. Which one is correct? I do use SNMP to monitor the same volume and should alert me when < 10% is free I know this works as I set the alert threshold to < 90% I get an alert.
View 2 Replies View RelatedGeneral :: Add / Of 3000mb In The Remaining 20380mb Free Space It Showing An Error Message That No Free Space Is Available
Jul 25, 2010I have 160gb laptop. i installed vista in c primary partition which is 25gb and installed ubuntu in d primary partition which is 20gb. A remainig for my data. Now i tried to install CENT OS by formatting ubuntu. I inserted CENT OS DVD and restarted and i selected to delete my /dev/sda2 which is showing 20480mb and it shown me free space. but i tried to add partion /boot of 100mb it got added. but, when i am trying to add / of 3000mb in the remaining 20380mb free space it showing an error message that no free space is available.
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Dec 8, 2009We're load testing some of our larger servers (16GB+ RAM), and when memory starts to run low they are kicking off the oomkiller instead of swapping. I've checked swapon -s (which says we're using 0 bytes out of 16GB of swap), I've checked swappiness (60), I've tried upping the swap to 32GB, all to no avail. If we pull some RAM, and configure the box with 8GB of physical ram and 16 (or more) GB of swap, sure enough it dips into it and is more stable than a 16GB box with 16 or 32GB of swap.
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Aug 30, 2010I got the VMrss used by a process as about 2GB, but the physical memory of my computer is only 1G.
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Jan 2, 2011Before running SOSreport, the free physical memory is 5389Mb out of 8Gb.
After running SOSreport, the free physical memory is 3229Mb.
Why is this so? how we can free up the physical memory.
Fedora :: Managed To Reduce The Logical Volume To Free Some Space But Cant Seem To Reduce The Physical Volume
Jan 1, 2010so i have f12 installed on my hd with lvm using the whole extent of the HD , i want to reduce it so i can dual boot it with a windows system, i managed to reduce the logical volume to free some space, but i cant seem to reduce the physical volume, is this possible and how ?
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Oct 20, 2010I am monitoring physical memory in a server I administer, and my hardware provider told me they had increased physical memory size to 4Gb... However, using several tools (free -m; top; dmesg | grep Memory; grep MemTotal /proc/meminfo I discovered that I actually have 3Gb, not 4... But, my doubt comes from the fact that dmesg | grem Memory tells me I have 3103396k/4194304k available The first number is effectively 3Gb, but the second one, is 4! so, why I am looking at this two different numbers?
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Apr 29, 2011Before I start a flame war, I'd like to qualify my question with...I have a boatload of ram and a VERY thin install.(CLI openSuse 11.4-64) If I'm running the most baseline, text-only-install...and the whole system install is like 2GB or less, and I have 8GB of ram (which I could easily upgrade to 16). At install time...do I really need a swap partition at all? What purpose could a swap serve if I have that much ram in such a trimmed down environment?
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Jan 30, 2010swap space consumed is not released when there is enough main memory. pls advise how to release used swap space.
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Mar 20, 2011How to add swap space?
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Aug 23, 2010just some time ago, my /usr partition's used space is started to increase rapidly, and currently it reached 17.5GB. We put /usr as a separate partition (/dev/sda2)
So when we do "df" this is the result:
Code:
#df
...
/dev/sda2 20315844 17612628 1654576 92% /usr
...
But what makes me puzzled is if I do "du", I only get 4.3GB instead of 20GB as "df" reported.
Code:
# du -csh /usr
4.3G /usr
4.3G total
So I'm missing approx 13GB here. My question is:where does my 13GB missing?
Server :: Ubuntu Doesn't Move To The Memory And Empty The Swap
Feb 2, 2011In 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]....
Ubuntu :: Swap Or Swap File On Flash Memory?
Aug 16, 2010RAM 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?
Server :: How To Check Disk Free Space
Apr 23, 2010[root@linux root]# fdisk -l
Disk /dev/hda: 40.0 GB, 40020664320 bytes
255 heads, 63 sectors/track, 4865 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hda1 * 1 13 104391 83 Linux
/dev/hda2 1276 4864 28828642+ f Win95 Ext'd (LBA)
/dev/hda3 14 395 3068415 83 Linux
/dev/hda4 396 526 1052257+ 82 Linux swap
/dev/hda5 1276 3187 15358108+ 7 HPFS/NTFS
/dev/hda6 3188 3249 497983+ 8e Linux LVM
/dev/hda7 3250 3311 497983+ 8e Linux LVM
Here /dev/hda5 taken of How much capacity for NTFS (need space in MB).
Server :: How To Determine Swap Space Usage For Processes
Jan 10, 2011On one of my servers the "free" command tells me that a lot of swap space are in use. What I'd like to do is to determine which processes have been swapped out. I tried issuing "top" and sort by the "swap" column, but this doesn't seem to provide correct values - when performing the same excersize on another server with close to no pages swapped out, the sum when adding the swap value for each process greatly exceeds the swap usage reported by "free". So how do I go about determining the swap space used for individual processes?
View 7 Replies View RelatedGeneral :: Division Of Logical Memory Space In To User Space And Kernel Space
Jan 4, 2010Logical Memory Space of 4GB is divided in to 3GB User Space and 1GB Kernel Space. Always. Correct?
1. How can we change it? (just changing value of PAGE_OFFSET is okay?)
2. If system have only 256MB of memory (embedded system) and suppose Kernel Modules eat away all the memory during boot. User space will be left will no memory. Is this case possible?