Questions tagged [virtual-memory]

It is an extension of memory address space which is logically appended to the physical memory of a computer by the Memory Management Unit (MMU) of its processor. It is normally realized in operating systems by utilizing free disk space to implement such memory extension and may also be referred to as swap-file or page-file.

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Can virtual memory exceed physical memory? (RAM + Hard Drive)?

The glances program tells that a google chrome page consumes 1.10 TB virtual memory and my PC does not have this capacity (RAM + Hard Drive). About this, quora explains the following: "virtual ...
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What does lower case "g" mean in top output?

Can someone please help explain this, I have always used to interprete the "g" in top output to be size in Gigabytes even though the convention is to use uppercase "G" but now I am ...
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Why does writing to a workbook of a few MB with Python's openpyxl module eat Gigabytes of RAM?

I found an old code on a legacy server that writes from a dataset of roughly 20 columns and >60K rows item by item to an Excel file using openpyxl. It does this by filling each cell on its own (the ...
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Swap memory 95% on SQL server running on Windows Server

I had an interesting situation the other day where a customer's SQL server was at 95% swap memory utilisation. This occurred on a Windows server running SQL Server. The customer has 64GB RAM, and the ...
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Does z/OS enforce memory protection between processes of the same user?

It is often pointed out that each user has their own (virtual) address space in in z/OS; this is said as if it is a good thing, and I suppose it is compared to real mode. But in most modern systems I'...
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Running out of memory with plenty of memory and swap

I have a Debian-based system that is running out of memory but there appears to be plenty of free memory. The box will run for about 6-12 days and then it will begin killing anything allocating memory ...
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Is it possible to set vm.overcommit_memory =1 only for specific containers?

So, I'm running a container that is showing this in the log: WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = ...
J. Scott Elblein's user avatar
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Does Cached includes Mapped pages in /proc/meminfo?

The Linux kernel definition for Cached memory does not mention it includes Shmem and Mapped pages (https://www.kernel.org/doc/Documentation/filesystems/proc.txt), but I've found some references where ...
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pagefile.sys How exactly does windows determine what drive to use with automatic management?

I have a 2016 Windows Server that has two drives, C: (system drive) H: storage drive. When I go into the Virtual Memory settings, H: is managed and C: is not. Note: "Automatically manage paging ...
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What is the exact meaning of EPTP with Extended Page Tables?

EPT stands for Intel Extended Page Tables. But what does the suffix P stand for in the term EPTP switching ? If there is a reliable source, I would like to add the answer to the Second Level Address ...
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Dell PowerEdge T-620 - Choosing Memory Modes in the BIOS

I'm trying to configure the Memory Mode, in the BIOS, of a Dell PowerEdge T620 with dual processors: Owner's Manual | Technical Guide The system has 384GB of DDR3 LRDIMM Memory and I'm able to choose ...
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Guest machine using all the RAM allocated to it on server [duplicate]

I have a server that has KVM installed on it. this server I have created for testing purposes. server's configuration : OS: CentOS 7 Space: 60GB RAM: 2GB I created one Windows VM on this server with ...
Akshay Rathod's user avatar
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Linux: The difference between "paging on major page fault" and "swapping enabled manually"

On a Linux machine, we can enable swap by commands like the following sudo fallocate -l 500M /data/swapfile sudo chmod 600 /data/swapfile sudo mkswap /data/swapfile sudo swapon /data/swapfile But ...
John the Traveler's user avatar
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Committed/Allocated memory in Linux is less than used memory. How is that possible?

So I have a system with linux kernel 4.14.73 in which I am using values from /proc/meminfo in an program that shows the system specs including memory used and memory reserved. All was well until I saw ...
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Is buddyinfo valid in virtual machines

Buddyinfo shows number of contiguous pages for each order available. Since virtual machine treats host's virtual memory as its physical memory does any kernel module allocating higher order memory ...
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Managed hosting, VPS & RAM - Virtual Memory?

I'm talking to a web host that's just starting up. They have shared hosting and managed VPS's. With shared hosting I understand that they have a script checking if a process goes over memory limits ...
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Windows Memory Usage - Is something throttling available RAM

Can anyone tell by the images below if this machine is unnaturally throttling memory usage. The memory was upgraded from 32GB-64GB for SSRS report rendering, which is the only sizable process to run. ...
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How to increase the Java Memory in Windows Server 2012 R2?

I am trying to follow This Link to increase the memory that is available to the Java Runtime Environment, because I encountered the "insufficient memory for the Java Runtime Environment to ...
user3768495's user avatar
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Remove swap completely or set swappiness to 0?

In managing a server with 512GB of RAM I encountered a process that keeps consuming swap until it hits 100% of the swap space then stops consuming more (6GB of swap) but keeps working fine (albeit, ...
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System freezes when syslog fills up with "java: page allocation failure"

Ubuntu 16.04 x64bit kernel 4.4.0 cpu:8 , memory:31G , ZFS is main filesystem and cifs share is mounted # sudo numactl --hardware available: 1 nodes (0) node 0 cpus: 0 1 2 3 4 5 6 7 node 0 size: 32157 ...
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What are the specific column headers for the "Mem-Info" dump after "oom-killer"

I'm running a Debian 8 Jessie development server. 16GB mem. I've looked at the other posts about oom-killer, but none are really pertinent to what I'm asking here I'm trying to track down what ...
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Windows Server 2016 pagefile does not increase

I apologize in advance if this is not clear enough to understand my problem, it's a bit long but I've done my best to make it understandable. I'm running an Exchange 2016 CU6 on a Windows server 2016 ...
Simon Cateau's user avatar
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Error: No space left on device: (deleted)/dev/zero

**** Hoster something changed on hypervizor but said, that nothing was changed. The problem is not on the server anymore... **** Could someone help me to solve the following problem: If I want to ...
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Centos 6.8 kernel 2.6.32-642.el6.x86_64 crash at linux-2.6.32-642.el6.x86_64/mm/vmalloc.c: 630

I have intel servers running CentOS 6.8 as KVM host,and there was an OOPS or BUG occurs. kernel crash at kernel-2.6.32-642.el6/linux-2.6.32-642.el6.x86_64/mm/vmalloc.c: 630 Did anyone else have this ...
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Linux OOM-killer acting despite plenty available memory

Once a week or so the OOM-killer shoots down a postgres process in my server, despite that 'free' states it has plenty of available memory. I have read several threads here and there, but cant see ...
Alexander Kolodziej's user avatar
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used (linux) memory not equal to sum of VmHWM? finding missing memory

I have a server (virtual) running Linux (Ubuntu 16.04 amd64). It has 8gb memory allocated, and it's all being used, but i don't know by what. root@server:~# free -k total used ...
Alexander Kolodziej's user avatar
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Overcommiting Memory with KVM and Libvirt

TL;DR; What is the best practice for overcommiting memory with libvirt and kvm ? Long story - I have a small and underutilized server running multiple VMs (both host and guest running centos 7.4) ...
Yoni Jah's user avatar
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VMWare not changing RAM on virtual machine

It's my first time posting on this platform so I'll try to be as detailed as possible with my question. This year I started working with servers and virtual machines for the first time, so I'm just ...
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Linux: How do I explicitly swap out everything possible?

This is essentially the reverse of "Linux: how to explicitly unswap everything possible?". I want to maximize the amount of available free memory before running a process I know will use system ...
Omnifarious's user avatar
6 votes
1 answer
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Different linux page cache behavior for servers doing the same work

I have two sets of servers w/128G memory, distinguished by when they were provisioned, that are behaving very differently while running the exact same daemon (elasticsearch). I am using elasticsearch ...
Erik B's user avatar
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hyper-v virtual machine dynamic memory warning

I have a virtual machine that uses dynamic memory in my hyper-v manager. startup memory: 1024 MB min: 1024 MB max: 4096 The memory demand (4300MB) of this vm is greater than the assigned memory (...
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Server responsiveness and swapping

I know how swapping basically works, why it's automatic and why it's generally a good thing. There is, however, a common scenario where I wish I had more control. I write LOB web applications with ...
John's user avatar
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What is the default maximum value for /proc/sys/kernel/shmmax

I am having an amiguity as to what the maximum value in shmmax should be set. After having a look at my system's statistics, it shows the following: #cat /proc/sys/kernel/shmmax ...
Parth Pathak's user avatar
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Ratio Recommended Paging Space

How would you find the approximate ratio of recommended paging space to RAM size? and does the currently allocated paging space= recommended? Where is the recommended paging space? I used the top ...
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Is there a point to having Windows manage the page file size and have a "dedicated" swap drive

On a SQL 2008R2 box we recently had a number of jobs fails for various reasons that were mostly memory related, including one stating the page file was full. The Windows 2008R2 VM had 16GB of RAM and ...
Matt's user avatar
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On Linux (CentOS 7.2), why does ulimit -m not appear to restrict memory usage?

I have set ulimit -m 1000000 for my shell, then started a process that consumes a bunch of memory (a simple python script from https://unix.stackexchange.com/questions/99334/how-to-fill-90-of-the-free-...
Mike S's user avatar
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Server appears to have little free memory despite apparent low memory usage in userspace

A Linux server I administer has been experiencing serious performance degradations as of late, becoming particularly apparent several weeks after each time it is rebooted. In particular Jenkins jobs ...
Benjamin George Roberts's user avatar
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Ubuntu memory consumption

I've got the following output of the free -m command screenshot So as far as I understand, 6501MB is available for using. The problem is that I have a cron job executing some SQL and I've noticed ...
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2 answers
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Slab reclaimable memory is not freed when needed

Correct me if I am wrong, but to my understanding slab reclaimable holds cached kernel objects which can be freed if needed. So if application needs to allocate more space, even if the 'free' memory ...
Horkyze's user avatar
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VirtualAlloc() failed: [0x00000008] Not enough storage is available to process this command [closed]

I keep getting the following error in my PHP error text for Xampp on Windows 10. Using WordPress as the CMS. Feeling like I have tried everything but hoping there is at least one person here that ...
Gary Carlyle Cook's user avatar
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1 answer
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Linux Mint: Python process gets "MemoryError" before swap is even close to fully used [closed]

I'm attempting to run a Python script that requires a lot of Virtual Memory. I'm on Linux Mint 17.3 64 bit and Python 2.7. As the Python process grows, I can see (using free -m) the amount of RAM ...
user1084684's user avatar
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Is there a way to check if my Virtual Memory Paging is "System Managed"

For one of our applications, we need to configure virtual memory on a Windows Machine to be system Managed. This can be done manually under System Properties -> Performance (Settings...) -> ...
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System process: high virtual memory usage

Azure virtual machine (3,5 Gb) with Server2012 running 2 IIS8 sites. At some time after reboot, System (pid 4) Private Virtual Memory reaches limit (15 Gb) with 2004 event: Windows successfully ...
smg's user avatar
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Does an NFS client incur read/write page faults proportional to bytes read to/written from server?

Perhaps my knowledge of virtual memory has been supplanted by too much other junk. Recently I ran some database benchmark tests where all data was to be stored on an NFS server and accessed via NFSv3 ...
Marc C's user avatar
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Linux vm.vfs_cache_pressure affect page cache or not?

I want to limit page cache in linux. Some documents say increase vm.vfs_cache_pressure to control the kernel reclaim memory. I try, but not work. Linux/Documentation/sysctl/vm.txt say "Decreasing ...
KOMEDA Shinji's user avatar
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Does Microsoft SQL Server have something similar to 'sqlite:///:memory:'?

Python 2.7 SQLAlchemy Microsoft SQL Server Management Studio 10.50.2500.0 Microsoft Analysis Services Client Tools 10.50.2500.0 Microsoft Data Access Components ...
BurningKrome's user avatar
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Linux max. value for vm.max_map_count

I'm planning to increase significantly the default value of 65k max mappings; let's say multiply by 10. Assuming we have enough memory on the machine is there anything I should take care of doing that?...
Marc Polizzi's user avatar
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1 answer
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Why does Windows Server 2012 R2 Standard edition show only 20% of my available memory?

Fellow Techies-- I have a LENOVO x3650 X6/x64 based Windows server with 4 18 cores/36 logical processors-- with installed physical memory (ram) @1.5 TB, total virtual memory @1.5 TB. However, I am ...
plditallo's user avatar
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File writes stall during heavy disk I/O on Linux box

I have two processes running on my box => A and B. Whenever there is heavy disk I/O activity caused by writing large files to the disk by process A, I see that file writes in process B are stalling ...
Stormshadow's user avatar
1 vote
1 answer
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Available virtual memory size is less then pagefile size

When Windows runs out of memory commit size it starts showing 'Low memory' window and performs slowly. This low-memory warning is not directly related to free physical memory amount. One can have 7Gb ...
Max The Cat's user avatar