cache is a component that stores data so future requests for that data can be served faster; the data stored in a cache might be the results of an earlier computation, or the duplicates of data stored elsewhere.

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34 views

stop server side caching file (Centos 7, Apache)

I set up a server but I need to disable server caching temporary on my website to see my changes. I actually set up another website on my sub-domain so it would be better if I disable caching by ...
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9 views

“Cache status for node is full”Both the system hard drive and storage drive are getting full in one day [closed]

I have 30+ cameras in one NVR and I'm using two 500GB hard disks for the operating system and four 2TB hard disks for storage. It was working for four years with no issues but after we installed 2FA ...
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0answers
12 views

MOD_PROXY with Squid

I am not entirely sure how to ask this question so it may have been discussed before. Attached below is an image of my image server setup. Here is how it works: A User visits my real estate website ...
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1answer
38 views

Does Linux Cache Hardware Info?

Questions Does Linux store hardware information between boots? (Such as EDIDs) If so is it possible to configure what gets cached? Background The reason I ask is that I currently am trying to ...
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1answer
28 views

ISP caching old DNS

I'm hoping one of you guys can help me. My ISP in the UK (Virgin Media) is caching DNS settings. I change the name servers of any domain and / or DNS settings. If I use whatsmydns.net I can see that ...
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1answer
37 views

How to load directory into filesystem cache?

I have a several GB directory that is rarely accessed, but when it is I'd like to be able to read the files in it quickly instead of having to wait. Since the files are rarely accessed they will not ...
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0answers
29 views

Force dirty pages limit in kernel sources

First of all, I'm not sure if that's a solution to my problem. My problem is that during I/O embedded linux is allocating too much memory in cache causing OOM if I run anything else. I/O operations ...
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0answers
13 views

i whant to clean the shared and the buff/cache memory [duplicate]

I want to clean the shared and the buff/cache memory, I'm not expert in linux but I want to learn. I have 2 gb of ram when i go through firefox the memory used is 900-1000 mb is this normal?? ...
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1answer
139 views

Failed to syncronize cache for repo 'fedora' … (possible proxy issues)

I just started on a fedora build. Just managed to add myself to the sudoers file, so now I am attempting to grab vim. I do a sudo dnf install vim and get hit with the following error message. ...
3
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1answer
66 views

Is it a good idea to put ~/.cache in a tmpfs?

I'm concerned about the ~/.cache directory for two reasons : it causes a lot of writes on my SSD unnecessarily, and it contains informations (like image thumbnails) about files in encrypted containers ...
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1answer
49 views

Vim saved file not updating on webpage

I am attempting to update an HTML file on my server, but when I do so it doesn't appear to be updating, but rather, serves an old copy instead. I went through the usual process of pressing :w and ...
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23 views

stop dm-cache from caching temporarily

I am want to benchmark my system(Centos) IOPS with dm-cache and without dm-cache.I have taken benchmark result for my system dm-cache .Now I want dm-cache to stop temporary so that I can take ...
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1answer
37 views

Error while installing Bcache on centOS

I am trying to setup Bcache on my existing system(Its risky,but we are not worried about losing any data ) . So my make and make install works proper but when I run the command make-bcache i receive ...
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1answer
151 views

device-mapper: reload ioctl on cache1 failed: Device or resource busy

When I run the below command while setting up dm-cache on my CentOS system, I receive the error: device-mapper: reload ioctl on cache1 failed: Device or resource busy Command failed Command is: ...
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0answers
12 views

Which is the correct dm-cache version

I am trying to install dm-cache on my CentOS machine. Which dm-cache version should I use. I read on wikipedia as below: Another dm-cache project with similar goals was announced by Eric Van ...
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0answers
48 views

device-mapper error while setup of dm-cache

I am trying to setup dmcache using the tutorial https://wiki.mikejung.biz/Dmcache When I run the command `dmsetup create home-cached --table '0 976771120 cache /dev/mapper/ssd-metadata /dev/mapper/...
3
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2answers
67 views

Defer *all* disk writes, keep them in memory

How to temporarily stop synchronizing of dirty data with disk, instead just keeping it in memory. Clarification: I want to sync it later.
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1answer
41 views

How to deactivate linux page/disk cache?

I would like to turn off the disk / storage cache on Raspbian. I have done a serie of benchmarks on the microSD (http://jgp.net/microsd-card-performance-raspberry-pi/) but some people recommended I do ...
0
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1answer
28 views

ncmpcpp is damaged after experienced a crash

My problem appeared with ncmpcpp the console music player. I've used ncmpcpp to open a .pls file from the Browser window and it crashed perhaps due to encoding problems. Since then, Every time I ...
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0answers
185 views

How to interpret perf -e cache-misses:pp?

I find the behavior of perf top -e cache-misses:pp -p <my_pid> quite confusing. I own an Intel i5-3230M, running kernel 4.4.5 64 bit. If I just run that commmand, I get basically no samples ...
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1answer
221 views

How can I clear my cache?

I'm running a live CD linux distro and I'm getting out of memory exceptions. >java -version #Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000646e00000, 264241152, 0) ...
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1answer
54 views

-/+ buffers/cache & Swap

When should the usage of swap get started? or How do I know that my swap is being used? At least some times if not always, considering the default swappiness of 60 Also, why does free offer to omit ...
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1answer
31 views

How does the diff command handle caching?

I became curious when I was diffing two large (>326MB) files, and noticed that the second run took much less time than the first. This was frustrating, since I was trying to time the second run, to ...
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0answers
76 views

bcache not working as expected with ramdisk as cache device

I was trying out bcache but i don't have an SSD so wanted to use free memory as a substitute. As ramdisk is listed in /proc/devices as block device i assumed this would work OK but with below simple ...
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1answer
34 views

Is the iSCSI block device having client side-read cache (if yes how to disable)?

I have a remote block device with the test ext4 filesystem image. On the iSCSI initiator side, I have this device detected as let's say /dev/sdb. I am not mounting this filesystem but instead I use ...
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1answer
66 views

Using terminal to reset icon cache - which method?

I've been trying to find out how to reset the icon cache on my MacBook, and two methods seem to always be suggested. However, the two approaches differ slightly in the third line. Method 1 sudo find ...
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0answers
50 views

SSD + HDD performance from power on

I'm planing to buy a new laptop with a 128GB SSD and a 1TB HDD. And I would like to have reliability, performance and storage space from power up and during the whole runing time. During the running ...
4
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0answers
137 views

LVM cache and TRIM

I have set up LVM to cache a logical volume (located on an HDD) on a partition of an SSD (in writeback mode if this matters). As far as I can tell, this works correctly and the cache uses all ...
3
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0answers
79 views

How to cache block devices (for device mapper)?

problem / observed effect It seems that the page cache ignores block devices which are not opened. And worse: Reads from device mapper (DM) devices which use a cached device are not cached at all (...
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0answers
46 views

One SSD cache for two partitions on two separate disks?

I have two hard drives: one for my operating system and the other for other data. I recently bought an SSD drive that I would like to use an LVM cache for those two devices. The problem is that I ...
7
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0answers
233 views

Why are slab objects not reclaimed automatically

Everyday after a full system backup, various programs are failing with read errors until I run echo 2 > /proc/sys/vm/drop_caches to free reclaimable slab objects. For example, here's the output of ...
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2answers
71 views

how does o_sync trigger pdflush?

When I write using o_sync, the write call returns once the data has been written to the disk. But how does o_sync force Linux to write the data to disk? Normally you would have to wait a maximum of ...
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0answers
300 views

OpenLDAP as a Proxy cache only, no local database

I am trying to get a local LDAP proxy cache running. The idea is this: Currently a computer (A) is sending all ldap requests to a remote ldap server (L) Instead of that, there should be a proxy ...
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0answers
28 views

SSD as write target during reads

I have a real-time application which always writes data to a RAID 10 HDD configuration in a sequential manner at around ~50 MB/s. It uses mmap and writing should never be blocked due to waiting I/O. ...
0
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1answer
237 views

how to increase cache memory in centos

I have been facing a insuffient space in "/var/cache/yum" directory. due to this my gui of centos crashes.i want to increase the size of cache directory. also want to know the actual size of cache ...
2
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0answers
26 views

Which subsystem caches file reads?

I am trying to understand how exactly file reads are served from Page Cache. This will be useful when I will be implementing my own filesystem in the kernel. Is file content cached by VFS or ...
1
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1answer
118 views

Linux top -n 1 Command doesn't get update

I'm calling the Linux top -n 1 -b command from a Qt application to get the free CPU percentage. This application calls this command every 3 seconds, but the CPU usage seems to be updated only the ...
1
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1answer
48 views

Reset Bash's memory used for auto-complete

After renaming a file to a similar name, I noticed TAB was still completing the old filename (if it matched the letters so far) and not showing the new one. No matter how many letters I typed, it ...
2
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1answer
30 views

Is partition created by dd (and cached) instantly available for writing

I'm creating a partition (from backup) with dd and need to know if there is a need of some sort of sync/timeout before I can access it. As I know data may be cached in dirty pages. But what if I read/...
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63 views

How to configure some proxy like Squid to download specific URL only once?

I have read article about Windows 10 spying my activity and blocked all mentioned addresses on my router's firewall. This included addresses az361816.vo.msecnd.net and az512334.vo.msecnd.net ...
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0answers
28 views

what is left inside the cache even after clearing the page cache data?

I was trying to clear the cache using echo 3 > /proc/sys/vm/drop_caches Even after performing the above operation there remain some space inside the cache? When I check with free -m around it ...
1
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1answer
454 views

Using readahead in Debian Jessie

The article BootProcessSpeedup on the Debian Wiki lists a tip to speed up boot time. It says to install readahead and then #touch /etc/readahead/profile-once. It seems like an outdated article, ...
1
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1answer
72 views

Linux Gateway as Download Accelerator like IPCop's

We're running dnsmasq on a linux box inside our network for DHCP and DNS. I would like to add a download accelerator like IPCop's (http://blockouttraffic.de/ua_index.php) but without having IPCop as ...
4
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1answer
565 views

How does Linux handle block devices?

Today I learned that FreeBSD removed support for block devices entirely. While reading their rational for the decision I came across this: Block devices are disk devices for which the kernel ...
1
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2answers
723 views

Force dig to forget records

I would like to let dig always forget a DNS record. I mean if I do dig yahoo.com then I have a record back in with ttl for 1790 seconds. Even if I have no cache service installed, next time i do the ...
5
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2answers
236 views

How to enable package caching in dnf?

I started using fedora 22 and started learning dnf only to find out about two annoying facts: Almost every time I install or upgrade anything it has to rebuild the whole repository metadata cache ...
0
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1answer
110 views

why does my Ubuntu Virtual Machine slow down after a number of searches, and builds?

I recently learned that my Ubuntu Linux file system may cache the result of some commands such as searches, sorts, and perhaps build commands such as make. I run Ubuntu in a VM, and although I have ...
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0answers
19 views

CVMFS file access slow, although file is in cache

I have a directory in which there is a symlink to a file on CVMFS. When I first boot up, and do ls, it takes a long time (~a minute). The reason is that ls does fstat on each file to determine what ...
3
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1answer
255 views

How to run free command by crontab

I want to run this command: free && sync && echo 3 > /proc/sys/vm/drop_caches && free -m by cron. That way I can free my RAM and cache in an Ubuntu system. I'm using ...
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0answers
157 views

Opcache and shared memory issue

I installed zend_opcache on my server box , but I can not increase opcache.memory_consumption over 1600 . (example : 2048) . after increase following error occur in server : Fatal Error Fatal Error ...