Synonym for: RAM - Acronym for: Random Access Memory, a type of computer data storage.

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183
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13answers
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Any benefit or detriment from removing a pagefile on an 8GB RAM machine?

I'm running Windows 7 on a dual core, x64 AMD with 8GB RAM. Do I even need a pagefile? Will removing it help or hurt performance? Would it make a difference if this is a server or a desktop? Does ...
67
votes
3answers
59k views

Meaning of the buffers/cache line in the output of free

Why does my server show total used free shared buffers cached Mem: 12286456 11715372 571084 0 81912 6545228 -/+ buffers/cache: 5088232 7198224 ...
56
votes
11answers
12k views

Why drop caches in Linux?

In our servers we have a habit of dropping caches at midnight. sync; echo 3 > /proc/sys/vm/drop_caches When I run the code it seems to free up lots of RAM, but do I really need to do that. ...
44
votes
2answers
3k views

vSphere education - What are the downsides of configuring VMs with *too* much RAM?

VMware memory management seems to be a tricky balancing act. With cluster RAM, Resource Pools, VMware's management techniques (TPS, ballooning, host swapping), in-guest RAM utilization, swapping, ...
43
votes
4answers
25k views

In Linux, what is the difference between “buffers” and “cache” reported by the free command?

This is an old question that I've seen from time to time. My understanding of it is rather limited (having read about the differences a long time ago, but the factoid(s) involved never really stuck). ...
41
votes
9answers
12k views

Linux: how to explicitly unswap everything possible?

I've launched something that took lots of memory and now everything lags a lot. I guess all applications' memory has gone to swap in order to free some space for the memory-intensive process, and now ...
36
votes
5answers
16k views

How to understand the memory usage and load average in linux server

I am using a linux server which has 128GB of memory and 24 cores. I use top to see how much it is used. Its output is pasted at the end of the post. Here are two questions: (1) I see that each of the ...
33
votes
7answers
2k views

Database server: Small quick RAM or large slow RAM?

We are currently designing our new database servers, and have come up with a trade off I'm not entirely sure of how to answer. These are our options: 48GB 1333MHz, or 96GB 1066MHz. My thinking is ...
31
votes
5answers
72k views

Top - what does Virtual memory size mean? …linux/ubuntu

I am running top to monitor my server performance and 2 of my java processes show virtual memory of up to 800MB-1GB. Is that a bad thing? What does virtual memory mean? And oh btw, I have swap of ...
29
votes
9answers
30k views

How to reduce memory usage on a Unix webserver

I'm currently using a Joyent Accelerator to host my webapps, and it's working fine, however I need to reduce costs so I'm downgrading my current plan and that imposes some new memory limits (256M rss, ...
28
votes
9answers
6k views

To improve SQL performance, why not just put lots of RAM rather than having faster hard disks?

People keep telling me that in order to improve an SQL server's performance, buy the fastest hard disks possible with RAID 5, etc. So I was thinking, instead of spending all the money for ...
27
votes
3answers
18k views

Turn off the Linux OOM killer by default?

The OOM killer on Linux wreaks havoc with various applications every so often, and it appears that not much is really done on the kernel development side to improve this. Would it not be better, as a ...
24
votes
7answers
2k views

Is it necessary to burn-in RAM for server-class hardware?

Considering the fact that many server-class systems are equipped with ECC RAM, is it necessary or useful to burn-in the memory DIMMs prior to their deployment? I've encountered an environment where ...
24
votes
4answers
19k views

What is ECC ram and why is it better?

I've seen a dicussion about ECC ram use on servers. Why is it better?
24
votes
7answers
42k views

How to find memory usage of individual Windows services?

Task Manager shows the overall memory usage of svchost.exe. Is there a way to view the memory usage of individual services? Note this is similar to ...
22
votes
5answers
5k 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 ...
22
votes
7answers
21k views

Windows Server 2008 R2 Metafile RAM Usage

I have a server which runs Windows Server 2008 R2 x64 with 4GB of RAM which hosts around 2-3 million files, the majority of which are image files. Over a course of a week, I have noticed that ...
21
votes
4answers
2k views

Can MySQL effectively take advantage of 64 GB RAM?

We have been running into a problem where querying a table that has approximately 50 million rows, and has an index size of 4 GB (table size of about 6 GB) results in the database server swapping ...
19
votes
8answers
53k views

Should you disable page file with SSD?

I've been reading this question, and it has a lot of great information. But assuming you have more than enough ram, I think page file should be disabled on SSD to extend the life time. I know you ...
16
votes
2answers
4k views

Where did my RAM go?

Note: before you jump in too fast, yes I read linuxatemyram.com! I have a server with 64GB RAM. free -m says that my RAM is full, and it's not because of disk caching: total used ...
16
votes
1answer
10k views

Memory Usage Numbers In top/htop

Can someone please explain this top output. Each PHP process is using 30% of the total memory or of the used memory? Furthermore how can it be that the combined used memory across all the PHP ...
16
votes
4answers
15k views

How can I determine the cause of an apparent memory leak in my Apache/PHP based web app?

About once a week, but sometimes even a couple of times a day after running fine for days, my EC2 instances become unresponsive. Munin's memory graphs tell a pretty straightforward story: memory ...
15
votes
5answers
39k views

Dump a linux process's memory to file

Is it possible to dump the current memory allocated for a process (by PID) to a file? Or read it somehow?
15
votes
4answers
63k views

DIMMs: Single vs. Double vs. Quad Rank

What difference does the 'Rank' of DIMMs make to server memory? For example, when looking at server configurations I see the following being offered for the same server: 2GB (1x2GB) Single Rank ...
15
votes
1answer
13k views

How to interpret output from Linux 'top' command?

Following a discussion made HERE about how PHP-FPM consuming memory, I just found a problem in reading the memory in top command. Here is a screenshot of my top just after restarting PHP-FPM. ...
14
votes
10answers
17k views

Memory usage per user in Linux?

Let's say i have 20 users logged on my linux box. How can I know how much memory each of them is using?
14
votes
3answers
21k views

How to increase the amount of memory memcache uses?

I am currently on a Xeon 7550 server running Redhat x86_64 es5 with 32gb RAM. I have memcache installed and the only step remaining in the configuration is to set how much memory it uses. I had done ...
14
votes
2answers
1k views

What RAM options do I need to know before buying Server RAM?

This is a proposed Canonical Question about Server Memory. I have to buy a Dell R420 server and there are various combinations (1600 and 1333 MHz RDIMMS and UDIMMS) and Performance Optimized vs. ...
14
votes
5answers
6k views

Mirrored Mode RAM: Is it worth it?

Not really familiar with Intel's "Mirrored Channel Mode" for a Blade Server setup (your typical moderately-heavy MySQL OLTP database running on the bare metal blade; no virtualization right now). ...
14
votes
1answer
279 views

What is the Rowhammer DRAM bug and how should I treat it?

DRAM chips are very tightly packed. Research has shown that neighboring bits can be flipped at random. What is the probability of the bug triggering at random in a server-grade DRAM chip with ECC ...
14
votes
7answers
13k views

After upgrading to 2008 R2 Enterprise and installing more RAM, Windows can only see 4.00 GB

(I have also posted this on technet but I'm running out of ideas) I've upgraded from Windows Server 2008 R2 Standard to Enterprise in order to make use of more RAM. The server previously had 32GB of ...
14
votes
2answers
26k views

page allocation failure - am I running out of memory?

Lately I've noticing entries like this one in the kern.log of one of my servers: Feb 16 00:24:05 aramis kernel: swapper: page allocation failure. order:0, mode:0x20 This is what I'd like to know: ...
13
votes
7answers
7k views

Would you use ECC RAM in a workstation?

Is ECC RAM recommended for use in workstations, or is it something that only gets used in servers? If non-ECC RAM works in PCs, why would we need ECC RAM at all?
13
votes
2answers
18k views

Best Mysql cache settings for 8gb RAM dedicated mysql server using only Innodb (5gb database)

I'm a pretty big noob when it comes to setting up mysql for performance. And honestly I'm not worried about the fine tuning to squeeze every last bit of performance out of mysql, but I do know that ...
13
votes
6answers
40k views

Weird memory usage in Windows Server 2008 R2

I hope someone can help. We've got a Windows Server 2008 R2 machine with 16GB of RAM that keeps getting all its available memory eaten by something. Nothing in Task Manager or Resource Monitor reveals ...
13
votes
1answer
7k views

How does vm.overcommit_memory work?

When I use the default settings: vm.overcommit_memory = 0 vm.overcommit_ratio = 50 I can read these values from /proc/meminfo file: CommitLimit: 2609604 kB Committed_AS: 1579976 kB But ...
13
votes
5answers
37k views

How do I get SQL Server to release its memory?

I know SQL likes RAM, but releases it when Windows asks. I know this is how SQL is supposed to work. But I have a Windows Administrator who isn't convinced that SQL will actually return the RAM, and ...
13
votes
1answer
5k views

deleting linux cached ram [duplicate]

I have a webserver that has 8GB of ram and is running a pretty intensive php site (1 site) that does file manipulation, graphing, emailing, forums, you name it. The environment is far from static ...
12
votes
7answers
5k views

SQL Server - Force DB in memory?

We have a beefy Windows 2008 x64 server (4 x 4 core CPU, 32GB RAM) running SQL Server 2005 64-bit. We have a small (6GB) but very important database that is somewhat slow to access until the pages are ...
12
votes
2answers
5k views

How is memory usage reported in Linux?

Using ps, I can see the size, the vsize (same as top's VIRT?), and the rss (same as top's RES?). (One more I see in top is SHR.) Could someone summarize for me what these different fields mean?
12
votes
2answers
7k views

Find out which database in SQL Server 2005 uses how much RAM

A friend of mine asked me today (trying to calm down an agitated customer of his) how you could find out in SQL Server 2005 which database uses how much memory (in the server's RAM that is) at any ...
12
votes
3answers
3k views

Balancing RAM when using multiple CPUs

We have HP DL360 G7 server with one cpu and 16G 12G ram. We plan to add another cpu. So, we need also ram for second cpu. Is there any negative performance impact if we add different size of ram to ...
12
votes
3answers
18k views

How to get - number of threads per process?

This is one Ubuntu 9.10 server. Also how to see memory usage per process? Thanks
12
votes
7answers
2k views

How do I inventory the type and speed of a remote computer?

I'm on a Windows 2003/2008 corporate network with 100 users. I've been tasked with increasing the RAM on all end-user workstations. The problem is we have a mixture of different computers in our ...
12
votes
3answers
16k views

How to investigate a memory leak with Apache and PHP?

We're running a heavy Drupal website that performs financial modeling. We seem to be running into some sort of memory leak given the fact that overtime the memory used by apache grows while the number ...
12
votes
4answers
11k views

SQL Server 2005: There is insufficient system memory to run this query

One of our SQL Servers, which has been running stable for quite some time (years), has recently been throwing insufficient memory errors. From the Application Event Log, we see: Event ID: 701 ...
11
votes
11answers
11k views

Linux server is only using 60% of memory, then swapping

I've got a Linux server that's running our bacula backup system. The machine is grinding like mad because it's going heavy in to swap. The problem is, it's only using 60% of its physical memory! ...
11
votes
8answers
24k views

Get a history of CPU/memory usage

Is there someway to record Task Managers info about CPU and memory usage to examine later? Or an equivalent tool?
11
votes
5answers
1k views

Linux with 256GB of mem / 48 Cores - Machine starts thrashing/choking with tons of memory left

Machine: Dell r815, CentOS 5.4, 256GB of RAM, 4 x 12 Cores. We have an application that has a 275GB file. It does an in place sort on 20GB of data at a time i.e. it swaps bits around and replaces ...
11
votes
3answers
7k views

Virtual Machine memory usage not appearing in TaskManager

There's something about Windows memory management and it's relationship to TaskManager that I don't understand and I'm hoping someone can enlighten me. If I'm running a virtual machine (doesn't ...