0
votes
0answers
6 views

Rail's FileStore with Linux Disk Caching or RAMdisk?

I have a Ruby on Rails application that stores it's catched files on the filesystem (Rails file-system cache). I was thinking about changing to memcached Store, but a short test shows it isn't a big ...
3
votes
1answer
38 views

Evaluating uncorrectable ECC errors and fallback methods

I run a server which has just experienced an error I've not encountered before. It emitted a few beeps, rebooted, and got stuck at the startup screen (the part where the bios shows its logo and begins ...
0
votes
3answers
80 views

Automatically Kill/Restart Process(es) When Memory is Critically Low

I have a Debian Wheezy VPS box where am running a couple of Django apps in production. Ideally, would have tried addressed my current memory footprint issues by optimizing the apps, adding more RAM or ...
1
vote
2answers
36 views

vSwap vs Burstable RAM for OpenVZ

What is the big difference between vSwap and Burstable RAM? Does vSwap create and cause I/O by using disk? I know SWAP will use the disk so is vSwap the same as swap just virtualized in the ...
2
votes
2answers
137 views

How to free linux memory safely to improve server performance

We have a linux virtual server hosted through GoDaddy, and our site has been running slow recently. I poked around the server a bit (I am not a sysadmin and have very limited experience with linux, ...
2
votes
2answers
61 views

Memory used by unknown processes on OEL6 - without cache and slabcache

I've searched through "Where is my Linux memory?" questions, but I couldn't find a similar scenario for my kind of leak: OEL 6.3 x86_64 Linux with 6GB of RAM without any of my main components ...
1
vote
0answers
70 views

Where did my memory go on linux (no cache/slab/shm/ipcs)

This is a headless server with 8GB RAM (kernel 3.12)... even after only a few days, i get low on memory. in fact, this server has OOMed a few days ago... something is losing memory, but i don't know ...
2
votes
2answers
43 views

Lots of major page faults in CentOS

We have a fairly complicated PHP script that's generating a lot of minor and major page faults. $> ps -o min_flt,maj_flt,time,cmd,pid 4686 MINFL MAJFL TIME CMD ...
1
vote
2answers
81 views

PHP eats up all the memory

Since this morning one of our webserver's memory getting filled up by php which eventually going to cause the server to start swapping, slow down and become unavailable (an ssh login takes like 5 ...
2
votes
3answers
238 views

How to increase swap space on a live server

On Ubuntu 14.04, the swap file has to be increased as the memory and swap usage are reaching 100% usage. On a live production server, can the swap be increased with minimal disruption to the service? ...
3
votes
1answer
160 views

Growing OS cache in RAM causing high system CPU usage

Long question, so please bare with me: I'm having a weird issue with a server that I've never seen before. On a machine with ~30G of RAM with an application that takes ~10G (spread across hundreds of ...
0
votes
0answers
17 views

xen: domu require more memory than mem-set size

Assume that we have install two guest os in xen, named dom1 and dom2. Now, I start the dom1 and dom2, and both are configured with max-mem=4096M; note that my physical memory is 16GB. While dom1 and ...
1
vote
0answers
59 views

Unusually high nfs_inode_cache

My server is experiencing a high usage of nfs_inode_cache = 11G , im trying to figure out what's consuming all this , i know already that directories with large numbers of entries and deep directory ...
0
votes
1answer
33 views

lvresize: command not found - RedHat

No search results on google for this. So i am really confused now. I am trying to increase the swap space and lvresize says command not found. Please Help !! using RedHat 64bit
4
votes
1answer
200 views

Linux page cache slows down IO on dual cpu server with 64GB ram

I have a massive problem with the linux page cache which slows down the IO. For instance if I copy a lvm partition with dd, linux cache the data in the buffers or caches (free –m). That is not the ...
2
votes
2answers
193 views

Memory mapping files for a blazing fast webserver on Linux

Is there any simple way of telling Linux to keep a directory of files cached in memory? I realized that Node.Js and Apache are spending most time on file I/O, making users wait if you have a lot of ...
3
votes
1answer
83 views

linux oops message, is memory address virtual or physical?

In this error message: BUG: unable to handle kernel paging request at ffff8804c001fade Is ffff8804c001fade the physical memory address or virtual memory address?
0
votes
1answer
195 views

how to set up shared memory and make it available?

I try to setup shared memory for Sybase ASE 12.5 on CentOS. My server has 17G memory, I want to make 14G (=17-1-2)available for sybase. (1G for os, 2G for ramdisk 14 = 17-1-2). here is the info: ...
0
votes
1answer
49 views

Read in effective RAM usage on Linux

I'm running some programs on *nix inside of a container and I'm attempting to closely calculate the amount of RAM my process is using. It is my understanding that this information should be under ...
1
vote
0answers
71 views

Server hangs when copying files, importing db etc

I'm running centos with Plesk ( kernel kernel.x86_64 0:2.6.32-431.11.2.el6). We upgraded to 48GB. Currently we are experiencing strange problem. Whenever we try to copy some file, import database, ...
0
votes
1answer
85 views

CentOS 6.4 64-bit Memory Usage really not adding up

I recently migrated hosting providers and in the process my distribution changed from CentOS 5.9 64-bit to CentOS 6.4 64-bit. Despite having a little more RAM (1 GiB rather than 768 MiB) the new VPS ...
0
votes
2answers
111 views

Understanding difference between system and process memory in htop

I'm a bit confused by the memory stats that htop is reporting on one of our servers. On the top bars, it's showing system memory as: Mem: 456 / 7950MB So, looks very low usage. However, my main ...
1
vote
2answers
221 views

troubleshooting out of memory error messages from mysql

we have a web application (racktables) that's giving us grief on our production box. whenever users try to run a search, it gives the following error: Pdo exception: PDOException SQLSTATE[HY000]: ...
1
vote
1answer
52 views

No buffers in memory. What it means?

This is a memory stats from my VPS (OpenVZ). $ free -m total used free shared buffers cached Mem: 800 405 394 0 0 405 -/+ ...
2
votes
2answers
181 views

Where's my RAM if it's not in cache/buffers or used by processes?

I know Linux likes to eat my RAM, and that's great, but it doesn't quite account for what I'm seeing on a VPS (KVM) running CentOS 6.5. In fact, I'm missing at least 200MB on a 1GB VM. Where could it ...
0
votes
1answer
54 views

Debian 6 - Linux 2.6.32-5-amd64 - Samba server with 32GB swap - how should i reuse it?

today i have the mission to tuning a Debian samba file server, previously i never ever touched it. RAM = 16GB SWAP = 32GB first of i ran a parted -l and a free -h and i saw one 3TB hdd: /dev/sda ...
3
votes
1answer
230 views

Mysterious memory usage in Linux

We have some 64 bits Linux boxes (RHEL6) running on Microsoft Windows 2012 Server (Hypervisor) with the same problem. Those Linux guest servers are running in MS Windows Cloud (Hyper-V) with 16 hosts ...
0
votes
1answer
117 views

When does Linux run out of memory? [duplicate]

I'm trying to establish why a process keeps unexpectedly stopping, and one possibility is that the server is running out of memory, but I'm not sure I understand memory and Linux properly. Take the ...
3
votes
1answer
356 views

How do I get my memory channel(Single channel, Dual channel, etc) type in Linux?

I want to know what type of my memory channel in Linux, Single or Dual or etc.. 1.I try find it by check /proc filesystem, but didn't success. And then 2.I use `dmidecode` to get system informations, ...
0
votes
1answer
284 views

Worker MPM or Prefork? [closed]

I understand that there is a comparison topic between the two modules here but this is different. I was contacting cPanel support in order to help me freeing up some memory usage on the VPS. They ...
0
votes
1answer
318 views

Linux empty buffer cache command permission denied

I'm using the following commands to flush cache: # sync; echo 3 > /proc/sys/vm/drop_caches # sync; echo 2 > /proc/sys/vm/drop_caches # sync; echo 1 > /proc/sys/vm/drop_caches When I use ...
0
votes
1answer
138 views

What does TOP's DATA column mean?

I'm trying to figure out the meanings of all the different classifications of memory such as VIRT, RES, SHR, AND DATA. While I generally understand the first 3, I have no idea what the DATA column ...
1
vote
2answers
52 views

find out which memory pages are owned by kernel

I can obtain a wonderful memory map of all processes with the Linux command pmap $(ps -A | awk '{print $1}'|grep -v PID) | sort | grep \^0 It looks like ... 00007fd6dbf45000 4K rw--- ...
15
votes
5answers
1k views

Unusually high dentry cache usage

Problem A CentOS machine with kernel 2.6.32 and 128 GB physical RAM ran into trouble a few days ago. The responsible system administrator tells me that the PHP-FPM application was not responding to ...
2
votes
0answers
180 views

Why can't I malloc as much memory as `free` reports as being free?

The following C program allocates slices of 10MB of memory until it is killed by the Out of Memory killer. #include <stdio.h> #include <stdlib.h> #include <string.h> #include ...
0
votes
0answers
73 views

How can used physical memory exceed sum of 'resident' memory reported by processes?

Given the output of top shown below (which shows all processes currently active): how is it possible that this virtual server reports ~500M physical memory as used (used - cached, verified by free), ...
2
votes
2answers
263 views

How can free physical memory decrease while 'Res' memory used by processes is constant?

I observe the following behavior that I cannot explain: the amount of free physical memory reported by a server increases, while the 'Res' memory reported by the most memory-hungry processes (web ...
1
vote
0answers
66 views

Red Hat Enterprise Linux 4 - free -m shows high memory used in second line but no process actually uses memory

I have a Red Hat Enterprise Linux. I understand that top can show high memory usage, which is fine. free -m shows below output: $ free -m total used free shared ...
3
votes
3answers
289 views

High Memory 64bit server, not using all ram

I have several high memory linux servers running centos 64bit, and after 10-20 days of uptime I have noticed on all of these servers they dont actually use all the ram available to then (they all have ...
5
votes
1answer
179 views

Linux Kernel lowmem usage

I am debugging an issue where we are running out of kernel low memory and I am trying to identify who is using the kernel low memory thats contributing to the problem. Following is the meminfo ...
0
votes
1answer
106 views

Trading Engine running on RHEL 5.x [closed]

Before asking question quick background about myself working at one of trading company this is my 1st job as sysadmin I have finish my RHCE no experience how production server work. In our company ...
1
vote
1answer
91 views

Drop caches in Linux

I have an embedded Geode-based application server with 512MB RAM and I'm about to try to maximize free memory during applications workload, which uses MySQL database 5.5 with InnoDB quite ...
8
votes
2answers
3k views

How to find what is using linux swap or what is in the swap?

I have virtual linux (Fedora 17) server with 28GB RAM and 2GB swap. The server is running mysql db that is set up to use most of the RAM. After some time running the server starts to use swap to swap ...
0
votes
2answers
82 views

What amount of physical RAM would a typical “commodity class” server have, as of late 2013? [closed]

I'm trying to spec out servers for my company's infrastructure group to build. They tell me anything more than 2GB is too much, which I find ridiculous considering cheap DRAM is about 15 bucks a dimm ...
1
vote
1answer
370 views

Xen dom0 reports incorrect amount of RAM with dom0_mem set

I've done a fair bit of searching about this, but have found nothing that answers my question. I have a system with 6GB of RAM which acts as a Xen server. For reference, it runs Ubuntu 12.04. I've ...
1
vote
1answer
74 views

Understanding Memory Usage and Numbers in Linux

I have a web server running Apache that has some interesting numbers for memory usage. Looking at top I have the following memory information Mem: 11679976k total, 10917568k used, 762408k free, ...
0
votes
1answer
51 views

Postfix mysteriously stops running

My server has been experiencing this problem once every couple months: Application becomes unavailable to users Application log filled 100% disk space with an error message that it cannot connect to ...
-1
votes
1answer
160 views

Top not accurately showing memory usage [duplicate]

Top is not showing my memory usage accurately or is my VPS provider doing something strange? As you see in the picture bellow it uses 90%+ of the memory, but when you look at what processes that is ...
1
vote
1answer
206 views

How do I configure Linux to use less memory for caching?

I have a follow up question to 377448, but not enough rep to comment there. Before I get dinged for asking the same dumb question, let me say I've been reading a lot of similar posts and answers ...
2
votes
2answers
3k views

What does the sync command do?

I know what it does... I guess I am curious why it is fixing a problem in an application i've inherrited. I took over a fairly large tomcat application which acts as Red5 server for a bunch of flex ...