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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8
votes
2answers
990 views

Cleanup of temporary file ~/.cache/duplicity/temp failed

Often when I run Duplicity I see an error message like this at the end of the run: Cleanup of temporary file /home/user/.cache/duplicity/9a169830d41477b2dbc3c5b32edd4e8a/duplicity-MEXhMY-tempdir/...
1
vote
0answers
11 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 ...
3
votes
1answer
34 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 ...
1
vote
1answer
23 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 ...
1
vote
1answer
32 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 ...
0
votes
0answers
27 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 ...
142
votes
1answer
311k views

How do you empty the buffers and cache on a Linux system?

Prior to doing some benchmarking work how would one free up the memory (RAM) that the Linux Kernel is consuming for its buffers and cache? Note that this is mostly useful for benchmarking. Emptying ...
0
votes
0answers
12 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?? ...
4
votes
1answer
73 views

Is posix_fadvice / POSIX_FADV_DONTNEED functional in Linux?

If I am doing once only scanning across big files then do I need to worry about impact on the page cache or does the OS take care to avoid my scan causing pointless churn in the page cache. I want to ...
0
votes
1answer
53 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. ...
0
votes
1answer
28 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 ...
2
votes
2answers
830 views

how to check default cache mode for disk in kvm

KVM/qemu support various types of cache - none, writethrough, writeback. How to check which one is default and is used on system when no cache= is specified? For RHEL6 i found that it's writethrough ...
3
votes
1answer
42 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 ...
6
votes
1answer
302 views

Limit the inode cache used by a command

I want to run a task with limits on the kernel objects that they will indirectly trigger. Note that this is not about the memory, threads, etc. used by the application, but about memory used by the ...
5
votes
1answer
19k views

Is no caching mode page a serious error?

My server log displays the following error messages in RED: kernel: sda: sda1 sda2 kernel: sd 0:1:0:0: [sda] No Caching mode page found kernel: sd 0:1:0:0: [sda] Assuming drive cache: write through ...
0
votes
1answer
45 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 ...
0
votes
0answers
22 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 ...
2
votes
3answers
2k views

Increasing the size limit for /var/cache/apt/archives

I have 2 systems running Debian at home and I am trying to minimize the bandwidth use while upgrading the packages. How can I increase the size limit of the cache, so that I could just copy the ...
1
vote
1answer
26 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 ...
0
votes
1answer
101 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: ...
5
votes
2answers
208 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 ...
1
vote
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 ...
0
votes
0answers
42 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
votes
2answers
64 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.
0
votes
1answer
39 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
votes
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 ...
20
votes
6answers
9k views

How to cache or otherwise speed up `du` summaries?

We have a large file system on which a full du (disk usage) summary takes over two minutes. I'd like to find a way to speed up a disk usage summary for arbitrary directories on that file system. For ...
42
votes
5answers
50k views

Can I safely remove /var/cache?

I am running out of disk space and noted that I have a large /var/cache directory. Can I safely remove this? (using Arch Linux, BTW).
4
votes
0answers
153 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 ...
0
votes
1answer
173 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) ...
1
vote
1answer
69 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 ...
0
votes
1answer
44 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 ...
0
votes
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 ...
1
vote
0answers
63 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 ...
4
votes
3answers
661 views

Does sysctl kern.bufcachepercent not work in OpenBSD 5.2 above 1.7GB?

I run OpenBSD/amd64 5.2 on a system with 12GB of RAM, and I want to use about 6GB to 8GB for filesystem caching. By default, 5.2 amd64 comes with sysctl kern.bufcachepercent set to 20 (20%); I've ...
12
votes
3answers
31k views

How to read the local DNS cache contents?

I know that on Windows I can issue ipconfig /displaydns and I see the local DNS's cache content. How can I list the DNS's cache content in Linux? I would like to get as much as cross-distro solution ...
1
vote
1answer
61 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 ...
0
votes
0answers
47 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 ...
3
votes
0answers
74 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 (...
5
votes
4answers
711 views

Does bash have a built in caching command available (sort of like mktemp or sponge)?

I'm using the amazon ec2 command line tools, and the ec2-describe-instances tool is a little painful because of the 2-5 seconds it requires to make the request and display the output. I'm looking ...
4
votes
0answers
128 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 ...
1
vote
1answer
631 views

flashcache tuning

I installed flashcache version 3.1.1 and created a write-back cache. The performance is good as long as the percentage of dirty blocks is not too high. My application does heavy I/O at the beginning,...
13
votes
2answers
1k views

Why does Linux purge the memory cache when it is nearly full?

Here's what the memory graph looks like on a VPS running CentOS with 512MB of RAM and nginx/php-fpm/mysqld serving (mostly static) content to a couple thousand visitors per day. (those are days on ...
7
votes
1answer
1k views

How to use an SSD for caching, so my hard disks can spin down?

I've got a file server with a bunch of disks running together in a BTRFS pool and want to add an SSD for caching. I'm not mainly after speeding up things, but want to catch the regular small accesses ...
6
votes
0answers
210 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 ...
1
vote
0answers
45 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 ...
9
votes
2answers
60k views

How to clear memory cache in Linux

Is there any command that by using I can clean the cache in RHEL? I used this command: sync; echo 3 > /proc/sys/vm/drop_caches but it didn't work.
1
vote
2answers
68 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 ...
1
vote
0answers
252 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 ...
0
votes
0answers
27 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. ...