Questions tagged [disk-cache]

Disk-cache: reserved area in RAM to speed-up disk access

A disk cache is a cache memory that is used to speed up the process of storing and accessing data from the host hard disk. It enables faster processing of reading/writing, commands and other input and output process between the hard disk, the memory and computing components.

The memory can be part of the disk drive itself (sometimes called a hard disk cache or buffer) or it can be general-purpose RAM in the computer that is reserved for use by the disk drive (sometimes called a soft disk cache). Hard disk cachesare more effective, but they are also much more expensive, and therefore smaller. Nearly all modern disk drives include a small amount of internal cache.

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How Does The Linux Disk Cache Work With iSCSI and GFS2?

I'm planning to share a GFS2 filesystem via iSCSI to my web servers. Are the files read by my web servers cached locally using the linux disk cache stored in memory or are they only cached on the GFS2 cluster?
Travis Mijat
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Linux /proc/sys/vm/drop_caches in guest VMs

Question: Would it ever be a good idea to disable page cache inside guest VM's and instead rely on the ZFS ARC (and SSD based L2ARC) of the host? Context: I'm asking since I'm running a Proxmox cluster which is always showing around 90% use of RAM…
A. Nilsson
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Debian max_ratio setting for device not working

My debian 8 machine has 2 drives. Sometimes I move/copy files from drive A to drive B. Drive B is slow, so the file system cache is full causing the system to be slow/unresponsive when copying large files. To avoid that i wanted to limit the file…
Laord
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Confused by write cache flags

I'm looking to maximise performance of my hard drive by enabling write caching. I understand the risks in doing this, but believe them to be insignificant for how I will use it. On the HD Properties tab in Windows, the last two options are a bit…
userSteve
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Windows Server 2012 write caching

From MSDN: By default, Windows caches file data that is read from disks and written to disks. [..] Caching is managed per file object. The policy of delaying the writing of the data to the file and holding it in the cache until the cache is flushed…
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Disable nginx fastcgi_cache when disk is full

When there is no disk space, nginx is still able to work correctly. It can serve static files, and it can pass the request to a fastcgi server (such as PHP), and it can serve the dynamic response to the client. The problem happens if fastcgi_cache…
Pavel S.
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What is the "right way" to combine sync and drop_caches?

When I need to do echo 3 > /proc/sys/vm/drop_caches with a sync beforehand, is it better to use sync && echo 3 > /proc/sys/vm/drop_caches or sync ; echo 3 > /proc/sys/vm/drop_caches. Does it even matter because both commands are safe for the…
micxer
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Apache mod cache mem/disk saves the cache for 10 seconds and than re-cache

I have this set up in my 000-default: ServerName live.website.com DocumentRoot /var/www/live.website.com SetOutputFilter INFLATE;proxy-html;DEFLATE CacheEnable mem http://live.website.com/ …
yos mishan
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Disk cache (write back) disables automatically

some days ago I discovered (using Munin) that my server had high iowait times. The reason was that write cache was disabled. I enabled it using hdparm -W1 /dev/sda but after some time (ramdonly) it got disable again. No information about this…
Federico
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How do I see if my disk cache is disabled on Linux?

I have an ubuntu linux virtual machine here and I think there is no disk cache. For example this is the output from free -m: total used free shared buffers cached Mem: 512 98 413 …
Amandasaurus
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What is read cache in "[sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA"?

I'm trying to figure out what the read cache part of the following message refers to: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA Is it "IDE drive's read-lookahead feature (usually ON by default)" as treated by…
poige
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How to make two squid servers share the same disk cache?

I'm trying to setup squid proxy in a kubernetes environment as a caching server with 3 replicas. I wanted to know whether all three replicas can share the same disk storage, or I'll have to assign separate storage to each. Currently all three of…
Ardneliahs
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Run similar disk intensive tasks parallel or serial on regular Linux?

Scenario I'm on a regular Ubuntu 18.04 LTS with ext4 Filesystems. I'm using restic to backup my machines. Restic is a backup tool that support different backends (local, sftp, aws, gcs, ..) but only one backup destination at a time. So I can't tell…
nuts
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How can I disable caching for the volume in Windows 2012?

When I try to disable disk cache on Windows Server 2012, I get "windows could not change the write-caching setting for the device" error. How do I disable the disk cache?
real_sm
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Questions about Varnish file storage engine

I have Varnish cache in front of some websites with the following storage engine configuration: Storage: file Size: 130GB The server where it is installed has the following configuration: RAM: 7.5 GB SSD 1: 15GB (System) SSD 2: 150GB (130GB for…