Understanding Linux Memory Management

Jan 20, 2008

I've been working with Linux lately and been wondering how Linux (Fedora/CentOS) manages its memory usage efficiency.

What I've been noticing is, Linux uses quite a lot of memory for just a single application. For example, Firefox-bin uses like around 100mb of memory.

At the same time around, when KDE/Desktop Environment aren't installed, Linux uses very small memory for non-GUI applications, such as those of hosting-related services.

Isn't using 100mb of memory for a browser application a bit too much? Is the memory information under "top" command represents the physical memory available? Is there any difference in performance when in physical server compared to virtual server (virtuozzo for example)?

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Understanding Memory Usage

Mar 23, 2009

So I just need some clarification:

Code:

-bash-3.2$ free -m
total used free shared buffers cached
Mem: 2000 1131 869 0 219 513
-/+ buffers/cache: 398 1602
Swap: 4094 0 4094

How much memory have I used?

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Memory Management On VPS

Jul 27, 2007

1-On a VPS if I have 128 RAM guaranteed and 512 Burst, when I do top I can see the 471856k, it means at that moment I can use 471856k RAM, or this memory show is something I cant trust?

2- If I have 128 guaranteed and for some reason a a process tries to eat more than that(like 1 gig for exaple) it will be not allowed? Do I have to pay anything for that leak? DO the leak affects the ENtire host?

I believe I kno all those answer but is better to double check them....

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Virtuozzo Memory Management: SLM Or UBC?

Apr 10, 2007

I was wondering what the general opinion of both administrators and end-users was about either SLM or UBC (Virtuozzo memory management methods)?

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Yet Another Topic About Process/memory Management

Oct 23, 2007

Yet another topic about process/memory management : )

I have a 256 RAM VPS and I need to free up more memory, Im using cpanel and when i use the "top" command, those are the major memory consumers!

PS.: I removed some of the list cause I know i really need them

21635 root 16 0 20888 10m 1316 S 0 1.0 0:01.73 cpsrvd-ssl
13983 root 20 0 14644 8780 348 S 0 0.8 0:00.00 cpdavd
13994 root 34 19 9956 7376 1876 S 0 0.7 0:01.04 cpanellogd
3835 root 15 0 6592 5028 1192 S 0 0.5 0:00.01 chkservd
26595 root 17 0 6652 5020 2816 S 0 0.5 0:00.18 authProg
13911 mailnull 16 0 7664 4972 1544 S 0 0.5 0:00.14 eximstats
13993 root 15 0 6228 4436 1112 S 0 0.4 0:00.03 cpbandwd
13764 root 16 0 3524 1496 628 S 0 0.1 0:00.35 antirelayd
13692 mailnull 16 0 7404 1204 808 S 0 0.1 0:00.22 exim
13698 mailnull 20 0 7404 1144 756 S 0 0.1 0:00.00 exim
18140 mailnull 20 0 7404 1140 752 S 0 0.1 0:00.00 exim

So, my basic question is, which of them I donīt need? SOme of them I know what is it but still have some questions...

1-cpsrvd-ssl , i know this means someone(me) is connected to cpanel, but even if I log out the process stills there, is that normal ?

2-authProg , sometimes there are a lot of those process running, what is that? is that normal ?

3-exim, 3 process running, is that normal ? exim is better than sendmail ?

4-After those questions, which process am I able to drop(and how?) - I only need email forwarding(that is already working), smtp, mysql(already working too), and tomcat server.

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Plesk 11.x / Linux :: IP Access Restriction Management?

Apr 24, 2014

(Plesk version 11.09)

Trying to restrict access to plesk control panel to one IP address (fake 66.67.68.69).

When I add the network 66.67.68.69/255.255.255.254 I recieve the following notification:

Error: The access restriction policy and the list of networks are currently configured the way you will not be able to log in with administrator's rights from your IP address '66.67.68.69'.

Now I would like this to be the ONLY ip address from wich i can log in.

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Plesk 12.x / Linux :: Enable Firewall Rules Management

Jul 2, 2015

I just have installed plesk panel and when i get to the "Firewall" tool, then clicked on "Enable Firewall Rules Management", proftpd has stopped working properly.URLs....I have preinstalled the server 2 times, and every time i try to edit the firewall rules, proftpd got broken.

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Intel VPro/AMT - Management Tool - Remote Installation Of Windows / Linux

May 21, 2008

good remote management solution.

As the Intel vPro chip set looks very nice and has all this, what we need (remote power management, hardware analysis/informations, kvm, etc) we bought one main board with that chip set.

We had now the problem to find a software which has a good support for the Intel vPro chip set. We found and tried:

Intel AMT Developer Kit
LANDesk
Microsoft System Configuration Manager 2007
SyAM Software

The onliest software, which was install able and connect able at the moment, was the Intel AMT Developer Kit. Software like LANDesk and MS SysConfigMgr needs Windows Server Versions with and without Windows Domain. We succeeded (after fixing the requirements of each software) to install everything, but no software is able to connect to the vPro chip. Only the Intel AMT Developer Kit does.

The Intel AMT Developer Kit looks on the first look enough anf powerful. We can power on, off, reset, we see hardware informations, we can enter also the bios over remote console. But as soon as we want to start remotely a cd, for example simple memtest86 image, it doesn't gives any display.

Does someone of you has good experience in this system?

Has someone some suggestions, what software else is existing?

We want to manage linux/unix based and windows as well.

With manage we mean, to install and to maintain.

If here is some company, which can help us, also if it costs some money, we would be glad to get in touch.

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Plesk 12.x / Linux :: Fail2Ban Custom Filter Is Not Available For Selection In Jail Management

Mar 18, 2015

We are successfully using fail2ban on our server (CentOS 6.6, Plesk 12.0.18), that is, jails running and blocking potential intruders

However, we tried to create a custom jail for the CMS that is being used by most of our clients.

I followed the instructions (Tools & Settings > IP Address Banning (Fail2Ban) > Jails > Manage Filters > Add Filter) and created the filter I wanted, but then it does not appear in the list, even though it displays a message reading that the filter was created successfully. Then, if I try to create a new Jail, the filter is not available from the list.

Looking at the directory /etc/fail2ban/filter.d/ I can find a file that has the same name as the filter I created, with a .local extension (the file name does not contain whitespaces or other special characters)...

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Memory Usage On Linux

Jul 21, 2008

I have a dedicated server with 2 GB of RAM. I am concerned with my server's memory usage when I am currently not running many applications.

[root@digm1 ~]# free -m
total used free shared buffers cached
Mem: 1947 1896 50 0 106 1579
-/+ buffers/cache: 210 1736
Swap: 2047 0 2047

It tells me that I only have 50 MB of memory left and it drops down to ~20 MB after Apache has been running for a while. Once it runs out of that 20 MB I will start swapping right? I have also run this command and do not see any process taking up anywhere close to what is being reported:

ps -eo pid,ppid,rss,vsize,pcpu,pmem,cmd -ww --sort=pid

No process is using more than 1.5% memory and only 3 use this much.

Is Linux caching memory which will be used after I run out?

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Clean Memory, Linux

Jul 21, 2007

Is there a command to clean up my Memory in Linux?

I use Plesk 8, Linux

When i execute "free -m" command it shows me:

total used free shared buffers cached
Mem: 1006 959 47 0 136 567
-/+ buffers/cache: 254 752
Swap: 4095 0 4095

Version:
Command: free -V
Result: procps version 3.2.3

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Plesk 11.x / Linux :: How To Increase PHP Memory Limit

Feb 1, 2014

why, or when this happened, but all of a sudden the PHP Memory Limit for all of my domains is 64M? I used to have it set to 128. How to change this setting so that all domains have the ability to go to 128M ?

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Plesk 12.x / Linux :: Subscription And PHP Max Memory Assignment

Jan 19, 2015

When you create a subscription for a customer, there is a php max memory assignment in the service plan. I am wondering if the max memory is based on per website customer creates or it is based on per account..

if it is based on per website, that means if a customer create 100 website under one subscription....and per php max memory is 256m, that means they will be using max. 256mx100...is that correct?

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Understanding Scp

Nov 22, 2007

I want to use scp to backup files, however I find most tutorials confusing as to which computer is the remote and the local. Is the local the one you are logged into via ssh command, or the computer from which you logged into ssh.

Lets say I am on my Windows computer. I open up putty, and login to the ssh connection of a remote linux computer. What scp command do I enter into the ssh terminal to copy a file from D:ackup of the windows computer to /home/backup of the linux computer?

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Understanding APF

Oct 22, 2007

I am getting ready to install APF, I have read multiple articles, but am still confused with the following parameters and what needs to be included in each:

IG_TCP_CPORTS
IG_UDP_CPORTS
EG_TCP_CPORTS
EG_UDP_CPORTS

These are the ports that I want to use:
21,22,25,53,80,110,143,443,465,873,993,995

How do I know what port goes in what parameter? How do I know if it goes in TCP or UDP and if it goes in Ingress or Egress?

What is the difference between TCP and UDP?

Is it ok to have a port listed in both TCP an UDP, and also in Ingress as well as in Egress?

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Understanding APF

Nov 7, 2007

having my own dedicated server. I have apf installed and I wanted to see how it blocked IPs so I had a friend, whoes IP I knew, help me. I added his IP to the deny_hosts.rules, thinking that would block him from my server, but it did not. Now, mind you, the way I added his IP was to simply use an editor and add his IP to the bottom of the list. Then I got to thinking, does teh apf only load the rules every so often? If so, how can I tell when or how often the rules load? ALso, do I need to add an IP using apr -d IPNUMBER in order for the apf to recognize it? I'd appreciate some info on how the apf works and how I can add IPs myself that I want to add and be sure that they are being blocked.

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Understanding DNS

Jan 5, 2007

I am going to place my first physical server to a server room. I wish to use it also as an nameserver for my domains and I am missing some basic principle there. I can probably configure BIND etc, but how will the servers upper in the hierarchy learn that this is a nameserver for certain domains? To start with, I have several empty domains (they are not hosted and so far using nameservers of a big company).

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Plesk 12.x / Linux :: Increase PHP Memory Limit For All Hosted Sites

Nov 12, 2014

I am trying to increase the PHP memory limit for all Plesk hosted sites.

I've updated the 'memory_limit' setting in /etc/php.ini

Then I ran

Code:
/usr/local/psa/admin/sbin/httpdmng --reconfigure-all
/usr/local/psa/admin/sbin/httpdmng --reconfigure-server
Checking a phpinfo() page on hosted sites I see that this setting has not been effective.

Checking some /var/www/vhosts/system/domain.com/etc/php.ini also shows the old setting, and I can see that these files have not been updated.

I note that all these domain php.ini files have been modified earlier today, all at the same time, so presumably some process did regenerate them earlier. All these files hae the "DO NOT MODIFY ..." heading

I realise that I can go the the domain in Plesk GUI and save the PHP settings to force an update, but is there anyway to force the regeneration of all of these files via CLI?

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Plesk 12.x / Linux :: Server Running Out Of Memory By Sort Command

Mar 26, 2015

Why servers are being run out of memory by the 'sort' command even when the logs are small? Here's what is currently on a site:

-rw-r--r-- 2 root root 22392143 Mar 26 11:40 access_log
-rw-r--r-- 2 root root 68018869 Mar 26 10:50 access_log.processed.1
-rw-r--r-- 3 root root 67671664 Mar 26 09:50 access_log.processed.2
-rw-r--r-- 1 root root 69908 Mar 26 10:50 access_log.stat

[Code] .....

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Plesk 12.x / Linux :: Parallels Premium Antivirus Memory Hogg?

Dec 3, 2014

So I set up a Cloud VM to host a number of websites and as a precaution I enabled the Parallels Antivirus.... wow. The server memory usage has shot up from 55% to 108% when it is turned on.

This is bonkers - how can I reduce the memory back to a safer % while keeping the AV turned on? Are there other services that are non essential that I can turn off without effecting performance?

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Plesk 12.x / Linux :: Server Crashing Randomly With Out Of Memory Error

May 12, 2015

it's starting to kill child processes and eventually stops/hangs.

#plesk version
Product version: 12.0.18 Update #45
Update date: 2015/05/08 03:13
Build date: 2015/01/26 15:00
Build target: CentOS 7
Revision: 334346
Architecture: 64-bit
Wrapper version: 1.2

#free -m
total used free shared buff/cache available
Mem: 3782 647 2281 45 854 2875
Swap: 2047 0 2047

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Cpanel VPS - Plenty Of Free Memory, But 'committed' Memory Exceeds VPS RAM

Jun 12, 2009

I have a VPS. And have had an issue both when it was 1Gig and now I recently downgraded it to 768m, because I am moving some sites to a dedicated.

However, the part I am having trouble grasping is that when I look at graphs from Munin, it will typically always show 200-400MB free memory (and free -m and top agrees with munin), but Munin shows 'committed' memory that is above the total Ram on the VPS and once the 'committed' ram exceeds the VPS limit, processes start failing.

So, why is 'committed' memory exceeding the RAM on my VPS, when Munin, free -m and top all show there is free memory available?

Code:
root@server [~]# free -m
total used free shared buffers cached
Mem: 768 449 318 0 0 0
-/+ buffers/cache: 449 318
Swap: 0 0 0
Here's a graph that munin produces that shows the 'committed' memory exceeding the total memory.
[url]

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Understanding Traceroute?

Dec 31, 2006

I am still trying to diagnose a problem some members have on my forums, when they load a page it will load a grey screen (my background color) and stop, after 15-30 seconds+ it will finally load the page

i opened a ticket with my server co and they forwared it to the NOC, NOC said it was apache config problem, server co said it was fixed and was due to apache log reaching 2GB limit, logrotate installed

same problem still existed, opened tk with server management co, they tweaked httpd.conf and disabled logs, problem still exists

I asked 3rd management co about it, changed some settings in httpd, said it may be due to ads on the sites, i took out the ads and a stat script

problem still exists, the thing is the problem exists with some users and not others, doing speed tests to the server shows it is very quick, load is low, no i/o wait and i just installed the second GB of memory so memory is fine

this is happeneing to users on seperate forums, one using vB, one using IPB, so it is server/ hardware related, AMD barton 3000, with 2GB ram, nowehere reaching the bandwidth limit or 10mbps port speed limit

any ideas? doing tracerts to the server shows a timeout before the sites IP address, every time, but doing a tracert OUT of the server shows no time outs....

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Understanding The Traceroute

Dec 13, 2006

One of the other message boards that I am on has a server at LayeredTech.

Now they said in there they had no issues whatsoever with the network. But when I did this tracert: .....

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Understanding (DNS) Nameserver?

Nov 21, 2008

I have a basic understanding of their role and how they work in general (mapping domain names to ip addresses).

I'll start with my setup/scenario:
Plesk - (dedicated company server - serving parent site via WHMCS)
ResellerClub - (domain registrar)
Cpanel/WHM - (shared server)

1. What would be the recommendation for a new hosting provider when it comes to name server(s)?

2. Do most who have limited resources use the BIND service on each WHM shared server itself? So if you have umpteen shared servers you would have umpteen name servers, as well?

2a. If so is it preferred/recommended to ultimately use completely separate/dedicated server(s) for DNS services for all shared servers? What is common?

3. If using the WHM shared server itself is the common practice, what are its pros and cons?

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Understanding Exim_mainlog

Aug 24, 2007

For the last week or two my VPS keeps getting added to blacklists.

Yesterday I noticed that a website on the server was forward mail from a contact form to the clients AOL account, obviously scripts were completing the form on the website and that was being sent to AOL, who would of obviously blacklisted the IP.

I've stopped that now, but we're still getting black listed. I've had my VPS provider get exim to record the path that sent the e-mail, and there are no scripts on the server sending out mails that I should be worried about.

Some questions to help me.

How can you identify an outgoing e-mail? is it by the character '=>'? If so, is it normal for there to be e-mails being sent out:
2007-08-23 19:04:10 1IOH2K-00038j-Jg => /dev/null <shaun[at]sr8.co.uk> F=<aaron_straubegnvu[at]yahoo.com> R=central_filter T=**bypassed** S=0 QT=6s DT=0s
2007-08-23 19:04:10 1IOH2K-00038j-Jg Completed QT=6s

I'm puzzled as to why the server keeps being blacklisted, when I can't really see any problems in the log file?

The CBL website (which blacklisted us) says we were added at around 19:00GMT, so I've checked the logs for that time and can't really find much.

On the server there is one account with an autoresponder set as that person is away on holiday.

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Understanding Dotster VPS

Jun 20, 2007

I recently went from dedicated to Dotster VPS to cut down on price and also because I do not have as many of clients I once had.

I chose their cPanel Premium
[url]

Soon after I realized via the Virtuozzo Panel, that I have limits on everything
.
I was pretty upset that none of these limits were posted anywhere on Dotsters site and its a surprise not welcomed.

I want to post some images so maybe you can tell me if their limits are reasonable or if they are way off.

[url]

I had them actually raise my diskinodes from 400/500k to 600/700k
and also my quotaugidlimit from 100 to 200.

For some reason I have 162 ugid's but i have only restored 23 or so accounts on this server, with no other special things running besides the standards. Shouldn't I be around under 100 ugid's?

So my main problems that I have is the folowing limits:

diskinodes: I have only 35 gigs used of the 50 allocated, their initial quota of 500,000 seemed low. now they bumped be to 700,000 and i'm almost there.

quotaugidlimit: for only having 23 accounts it's crazy to believe that I had to have their initial limit raise to 200. I have noticed a lot more users like #2121, #13232, #124312 and so on compaired to my dedicated server. My dedicated had about 5, this VPS shows about 30 or so.

kmemsize: their limit is 18,022,400 bytes, which I always seem to be reaching.

privvmpages: hard limit is 292,912 and i'm usually exceeding this one.

Here is a screenshot of my QoS:
[url]

Also, I noticed once I reach/exceed limits, the first things to be shutdown is my webmail and cpanel and so on, but the sites stay up Is there a way of setting up which resources are shut down in what order? To have mail up is the biggest request. I rather have ftp and cpanel down first.

I am really not happy with what is going on and gaining some user feedback would be great. I really wish Dotster had a complete breakdown of limits, before I bought.

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Understanding Colo

Jul 15, 2007

A good amount of the threads in this forum are just people asking what co-location is.

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Plesk 12.x / Linux :: PHP Fatal Error - Allowed Memory Size Exhausted

Feb 12, 2015

I run few export procedures which take a long time ot process (lots of joined sql) and generate quite large output. Plesk 11.0.x required some php/fcgif adjustments but I got it to work.

Now I switched ot Plesk 12 and have to set it up again.

I started with Plesk / PHP Settings for this domain:

memory_limit set = 2G
max_execution_time = 600
max_input_time = 600
post_max_size = 2G

Default subscription has no setting for above values but I have added them per this domain os not sure why it ignores my 2G value?

Error:
mod_fcgid: stderr: PHP Fatal error: Allowed memory size of 1047527424 bytes exhausted (tried to allocate 84 bytes) in

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Understanding DDOS Attacks

Aug 3, 2009

I want to understand the mechanics of a DDOS attack. I have been doing a lot of reading about them this weekend.

The way I am understanding it, a DDOS attack is done at the network level. It may be requesting that pages from a given website, or websites, are served up, but it basically will effect the entire network. So if 'page display' requests are made to a website(s) that is hosted at ABC Hosting (example only), to the tune of 15GBs then I have to assume that the network will be terribly degraded. If that is so, wouldn't other servers also get taken out?

I believe the architecture of the internet is something like this (example only):

Gnax --> Planet, SoftLayer, RackSpace, etc.. --> Reseller --> Smaller Reseller --> Me

If that is true, is each level along that route using their own networking system or are they all dependent on ones that major Data Center uses?

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Understanding Munin Output

Apr 18, 2008

I use Munin to monitor the health of our servers, I can tell by looking at the graphs there's nothing to worry about, however, I'm struggling to baseline acceptable performance.what would be classed as 'normal' output for some of the more relevant munin graphs.

I've been looking at the Apache* modules and this is the output from one of our servers:

average of: 300 accesses per minute, 6 busy servers and 4.10MB a minute volume

max of: 1400 accesses per minute, 81 busy servers and 51MB a minute volume

This is a dedicated box running one site.

We have another box that is running approximately 30 sites

average of: 30 accesses per minute, 1 busy server and a 500K a minute volume

max of: 322 accesses per minute, 11 busy servers and a 4MB a minute volume.

These servers are pretty much the same spec, dual core 64Bit, 4GB of ram, two SATA disks in RAID1.

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