Questions tagged [memory]
Synonym for: RAM - Acronym for: Random Access Memory, a type of computer data storage.
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Any benefit or detriment from removing a pagefile on an 8 GB RAM machine?
I'm running Windows 7 on a dual core, x64 AMD with 8 GB RAM.
Do I even need a page file?
Will removing it help or hurt performance?
Would it make a difference if this is a server or a desktop?
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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
Swap:...
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What does Virtual memory size in top mean?
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 ...
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Caching/preloading files on Linux into RAM
I have a rather old server that has 4GB of RAM and it is pretty much serving the same files all day, but it is doing so from the hard drive while 3GBs of RAM are "free".
Anyone who has ever tried ...
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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. Isn't ...
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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 when ...
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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?
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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).
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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 ...
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3
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How to read memory usage in htop?
Here is my htop output:
For example, I'm confused by this ruby script:
How much physical memory is it using? 3+1+8+51+51? 51? 51+51?
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Does memtest86+ test memory which is used to run itself?
One of the common server failure scenarios is bad DRAM, sometimes even when ECC memory is used.
memtest86+ is one of the most useful tools to diagnose DRAM problems. As it loads itself at the start ...
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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 ...
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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 PC3-...
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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, ...
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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 Finegrained performance reporting on svchost.exe
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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?
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Should I be concerned that swap is being used on a host with nearly 40GB of free memory?
I have a production host, below:
The system is using 1GB of swap, while maintaining nearly 40GB of free, unused memory space. Should I be concerned about this, or is it mostly normal?
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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 ...
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How do I get notified of ECC errors in Linux?
How do I get notified, when a Linux machine equipped with ECC memory recognizes a memory failure? I'm interested in both correctable and uncorrectable errors.
if a message is written to dmesg/the ...
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Difference between 2Rx4 vs 2Rx8 RAM
My IT provider is convincing me there is no difference between a 2Rx4 and a 2Rx8 RAM. A little digging around informed me that x4 means 4 bits on a chip vs x8 means 8 bits. Which is good, but what ...
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 RAID&...
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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 ...
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What is ECC ram and why is it better?
I've seen a dicussion about ECC ram use on servers. Why is it better?
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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. ...
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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?
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What are the best possible ways to benchmark RAM (no-ECC) under linux / arm?
I want to test integrity and global performances of no-ECC memory chips on a custom board
Are there some tools that run under linux so I can monitor system and global temperature in the same time ?
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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 ...
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Page allocation failure - Am I running out of memory?
Lately, I've noticed 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
I'd like to know:
What exactly ...
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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?
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Should you disable the 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 the page file should be disabled on SSD to extend the life time. I know you ...
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Linux not freeing large disk cache when memory demand goes up
Running Ubuntu on a 2.6.31-302 x86-64 kernel. The overall problem is that I have memory in the 'cached' category that keeps on going up and will not be freed or used even when our application needs it....
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How can I tell how much RAM is installed on a FreeBSD server?
As per the title:
How can I tell how much RAM is installed on a FreeBSD server?
Thanks!
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Cent OS: How do I turn off or reduce memory overcommitment, and is it safe to do it?
From time to time "my" server stalls because it runs out of both memory and swap space. (it keeps responding to ping but nothing more than that, not even ssh).
I'm told linux does memory ...
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Would upgrading RAM in a HP LaserJet printer improve its performance?
Would RAM upgrade for an HP 4050N LaserJet printer matter?
We have this real workhorse of a Laser Printer. It's an HP 4050N and it's been in use for many years. In the past few years, I've noticed ...
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What is the difference between RDIMM vs UDIMM
I don't quite understand the differences between the two besides the obvious price differences. What does each offer over the other?
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How much contention is too much in VMware?
For a while now I've been trying to figure out why quite a few of our business-critical systems are getting reports of "slowness" ranging from mild to extreme. I've recently turned my eye to the ...
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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 ...
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What consumes memory in java process?
we are trying to investigate memory usage of java process under moderate load.
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
12663 test 20 0 8378m 6.0g 4492 S 43 8.4 ...
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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 ...
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How to have linux top command show memory summary in megabytes not kilobytes
Redhat EL5
I had my top configured the just the way I like showing the memory summary and swap summary in MB. I had to close my shell and then when I re-opened it, it is back showing in (default ?) ...
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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?
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Non-ECC memory with ZFS: a stupid idea?
I have a new server and am planning to upgrade the paltry 2 GB of memory to the maximum of 16 GB. (Theoretically 8 GB is the limit, but empirically 16 GB has been shown to work.) Some guides advise ...
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How to check if RAM is running in ECC mode?
I updated this post since I replaced the processor, but the core of my question (and unfortunately the results as well) are the same.
I built my first FreeNAS box and wanted to use ECC RAM since I ...
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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 (...
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