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17
votes
3answers
7k views

(How) can I create a tmpfs as a regular (non-root) user?

The distribution is an Ubuntu server running the 2.6.35-30 Linux kernel. I would like to have a directory that sits completely in memory. Is this possible without root privileges?
13
votes
1answer
2k views

Why is /dev full?

The /dev.. is full: SERVER:/dev # df -mP /dev Filesystem 1048576-blocks Used Available Capacity Mounted on udev 12042 12042 0 100% /dev There is no ...
12
votes
3answers
13k views

Move /tmp to RAM

I am trying to move /tmp to RAM and obey good practice: /var/tmp should NOT be placed in tmpfs, as it must survive reboots not mount /tmp as a stand-alone tmpfs, but rely on /dev/shm or /run/shm ...
12
votes
3answers
4k views

On system memory… specifically the difference between `tmpfs,` `shm,` and `hugepages…`

I've been curious lately about the various Linux kernel memory based filesystems. Note: As far as I'm concerned, the questions below should be considered more or less optional when compared with a ...
10
votes
1answer
878 views

What sets the size of tmpfs? What happens when its full?

What sets the size of the tmpfs? (On my machine it resides in /dev/shm) I can see its entry in /etc/fstab, but no notation of its size. When checking with df -h, it seems to be half the size of the ...
8
votes
2answers
3k views

Difference between /run and /var/run

Is there any difference between /run directory and var/run directory. It seems the latter is a link to the former. If the contents are one and the same what is the need for two directories?
8
votes
1answer
4k views

Tmpfs only with RAM

How to be sure that a tmpfs filesystem can only deal with physical and it's not using a swap partition on disk ? Since i have a slow HDD and a fast RAM i would like, at least, giving higher priority ...
7
votes
2answers
351 views

How to make files inside TMPFS more likely to swap

I'm using tmpfs for my /tmp directory. How can I make the computer decide to swap out the files inside the /tmp before swapping out anything that is being used by applications? Basically the files ...
7
votes
3answers
3k views

Proper way to disable tmpfs on /run/shm

How do I disable tmpfs on /run/shm? I searched through initscripts and found that the following code checks the entry in fstab, but what should I change to make it not mount /run/shm? I'm running ...
6
votes
1answer
4k views

use `/run/shm` (formerly `/dev/shm`) as a temp directory

Is it good practice to create a directory in /run/shm (formerly /dev/shm) and use that like a temp directory for an application? Background: I am writing black box tests for a program which does a ...
6
votes
1answer
263 views

How safe is it to increase tmpfs to more than physical memory?

My server has 2GB RAM and 120GB SSD, plus some RAID arrays for storage. OS is Debian 8 (Linux 3.16). I have a MySQL intense application that has tmpdir = /run/mysqld, which is a tmpfs configured by ...
5
votes
1answer
89 views

Regarding the creation and destruction of sensitive data on linux/unix systems

In modern file systems (and on modern SSDs) there is no guarantee that if you write over a file using a traditional utility (such as dd) that the data will be overwritten in-place and journaled ...
5
votes
1answer
2k views

mount /var/log as tmpfs in Linux

My current laptop hard drive (Seagate ST940818SM) is slow (max 42MB/s R/W speed) and out of space. Mounting /tmp and /var/tmp as tmpfs does a lot of performance improvement. So is it safe to mount /...
5
votes
1answer
1k views

Does tmpfs automatically resize when the amount RAM changes, and does it compete when there's multiple tmpfs?

If I have a tmpfs set to 50%, and later on I add or remove RAM, does tmpfs automatically adjust its partition size? Also what if I have multiple tmpfs each set at 50%. Do multiple tmpfs compete ...
4
votes
3answers
329 views

Do tmpfs and devtmpfs share the same memory region?

My system disk usage is like this: # df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/rhel-root 50G 39G 12G 77% / devtmpfs 5.8G 0 5.8G 0% /dev ...
4
votes
2answers
212 views

Swap on tmpfs (Obviously a bad idea, but is it possible?)

This question originated with a joke between co-workers about increasing performance by moving swap partitions to a tmpfs. Clearly even if this is possible, it's not a good idea. All I want to know is,...
4
votes
2answers
101 views

Can I mount a case-insensitive tmpfs/ramfs?

I would like to utilize the performance of tmpfs/ramfs for some file operations, but the programs/processes that use these files assume a case-insensitive file system. I cannot find any documentation ...
4
votes
1answer
11k views

Can fstab options uid and gid be the user-group name or must they be numeric?

I'm learning how to set up a tmpfs in fstab for my www-data user and I was wondering if I can use the actual user/group name instead if the numeric ids (personal preference)? I'm on Debian with ext4, ...
4
votes
1answer
809 views

tmpfs and vm.swappiness

I have started tuning a bit Linux VM performance on my system (yes. I know that vm.swappiness=0 will kill kittens but I found 30-40 as much better for me as it improved my latency - probably at cost ...
4
votes
1answer
218 views

change size of devtmpfs /dev/

My new kernel has CONFIG_DEVTMPFS enabled, and thus my /dev is mounted as devtmpfs. My old kernel was not using CONFIG_DEVTMPFS, and /dev used to be mounted as plain tmpfs. Now I have noticed, the ...
4
votes
1answer
89 views

How do I lock a growing directory in memory?

I want a directory to be fast to read from, like on tmpfs for some time. The closest thing is this: vmtouch -L -m 2G /path/to/mydir But this does not detect new or deleted files.
3
votes
3answers
3k views

How can I check to see if the /tmp directory on my CentOS 5.x system is mounted on tmpfs?

CentOS 5.x My understanding is that the contents of /tmp/ in CentOS 5.x can/are automatically purged by the OS via one of two methods: A daily cron task running tmpwatch If /tmp/is mounted on a ...
3
votes
2answers
42 views

Multiple tmpfs partitions

[mayur@mayur311-pc ~]$ df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 50G 3.6G 47G 8% / devtmpfs 3.9G 0 3.9G 0% /dev tmpfs ...
3
votes
1answer
209 views

How can I set up overflow /tmp partition?

I run Antergos as my OS. I have several drives in my computer: a 240gb SSD, a 320gb SATA hard drive, and a 120gb IDE drive. I store most everything on the SSD because I don't generally need more room ...
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 ...
3
votes
2answers
1k views

Per user tmpfs directories

Using the shared /tmp directory is known to have lead to many security vulnerabilities when predictable filenames have been used. And randomly generated names aren't really nice looking. I am ...
3
votes
1answer
326 views

What happens when a tmpfs volume is full and swap is full? Is Linux's OOM-killer involved? [duplicate]

I understand that if a persistent / disk-based volume is full, files need to be explicitly deleted to free up space before more can be added. Further, I understand that if memory is exhausted, the ...
3
votes
1answer
820 views

Does the (source) device in a tmpfs type mount mean anything?

I just went into /etc/fstab (Linux) and changed my line for /tmp (on which a specific ext4 partition was previously mounted) to tmpfs. This was clearly a bit silly, but I wasn't thinking. Anyway, I ...
3
votes
1answer
90 views

If tmpfs has bigger size than your RAM, how much RAM does it use? Are applications privileged for RAM?

If the size configured for tmpfs is bigger than the size of RAM, and there is a lot of stuff stored there in the tmpfs, how is the amount of RAM available to applications determined? If applications ...
3
votes
1answer
1k views

How to compress a TMPFS folder?

I'm looking for a way to compress a tmpfs folder on the fly. I would like to use it for a local cache folder with a lot of data. I know there is a way to use Redis with eg LZF compression, but I ...
3
votes
0answers
42 views

fstab doens't read mode value

Following this guide: I set my /etc/fstab file in this way: proc /proc proc defaults 0 0 /dev/mmcblk0p1 /boot vfat defaults,ro 0 ...
2
votes
1answer
428 views

What happens when a tmpfs is full and no swap space is available?

Let's say I have a setup with 16 GB of physical RAM, A tmpfs of max. 8 GB containing a file with 5 GB and A swap sized 4 GB. If I'd try to, e.g., create a copy of the 5 GB file on the tmpfs, what ...
2
votes
2answers
209 views

Graphical archive manager that uses /tmp

I am looking for a (preferably) graphical archive manager that can be configured to use /tmp as a scratch area for decompressing. My setup is as follows: I have my local workstation with /home ...
2
votes
0answers
28 views

Restrict /proc/mounts to avoid exposure of /run/user/

EDIT: Currently looking at this solution.. (namespaces), but still wouldn't mind any pointers for doing what I'm after another way. We have a custom SELinux policy on CentOS 7.2 which confines users ...
2
votes
0answers
200 views

Using shared memory through tmpfs and NUMA on x86_64/Linux

Here's what I'd like to do: put a file on tmpfs but ensure that all of it (all pages of it) ends up on the same NUMA node. First, I thought this would be trivial: I'd just mmap() a tmpfs file with ...
2
votes
0answers
421 views

Moving /dev/shm/ to /run/shm in Arch?

Dolphin (The KDE4 FM) would not receive file change notifications for /dev/shm, but for /run/shm. So now I would like to migrate /dev/shm/ to /run/shm, but I couldn't find the corresponding part in ...
2
votes
1answer
477 views

tmpfs performance

I use avconv to make screen recording of gameplays on linux (yeah, I'm sorry, I am one of them, but I get more excited about the scripts than playing it self), but recently my harddrive has gone and ...
1
vote
1answer
59 views

Why deleting big files from tmpfs is not instantaneous?

$ cat /proc/mounts | egrep ' /tmp ' tmpfs /tmp tmpfs rw,nosuid,nodev,relatime 0 0 $ dd if=/dev/zero bs=1M count=3000 of=/tmp/q 3000+0 records in 3000+0 records out 3145728000 bytes (3.1 GB) copied, 1....
1
vote
1answer
381 views

tmpfs : creating file in tmpfs does not change memory usage in htop/top

I read about tmpfs and got curious to get the benefits from it. So, I created a directory and mounted as tmpfs. So, as per theory, whatever is written in tmpfs gets stored on RAM directly and lasts ...
1
vote
1answer
989 views

special device tmpfs does not exist

I'm trying to speed up a project which uses a folder for cache by mounting the cache folder on tmpfs. But whenever I mount it I get this error message: mount: special device tmpfs does not exist ...
1
vote
2answers
272 views

How to create “real” RAM disk that reserves memory

I've been shortly using this on Linux Debian Jessie to create a "RAM disk": mount -o size=1G -t tmpfs none /mnt/tmpfs But I was told it doesn't reserve memory, which I didn't know. I would like a ...
1
vote
1answer
52 views

Creating and mounting a RAM disk at computer startup

This is how I create RAM disk manually on Linux Debian Jessie: mount -o size=1G -t tmpfs none /mnt/tmpfs The question is how do I make this automatic at each computer startup? I have never created ...
1
vote
2answers
174 views

Tmpfs mount for directories on another partition

I have /var on a 10Gb EXT4 partition separate from /. I want to stick /var/cache in RAM using tmpfs. The /etc/fstab entry would be quite simple: tmpgs /var/cache tmpfs size=500M,rw,nodev,nosuid,...
1
vote
2answers
471 views

mount tmpfs preserve current permissions

I have a directory of a web application cache and this has the permissions 755 (default), and I configured setfacl additional permissions. the problem is that when I restart the system, the ...
1
vote
1answer
58 views

migrating to systemd a startup-shutdown script that works with tmpfs and bindmounts

BACKGROUND INFORMATION : I have an init script that allows me to mount a folder to tmpfs, while bind-mounting the folder on drive to another location, so I can sync the contents (on startup, shutdown,...
1
vote
2answers
183 views

What is going on with Google Chrome and deleted files

Debugging some CouchDB problems, I was looking for (still open) deleted files: $ lsof -nP | grep '(deleted)' And to my surprise I found that Google Chrome has around 16900 such files: 15870 files ...
1
vote
0answers
98 views

Ubuntu 16.04 with read-only filesystem and writable layer

(This is a cross post from askubuntu, as I think here are more people to know how to get this working) I want to set up Ubuntu 16.04 like a live CD. This worked great in Ubuntu 12.04 but with 16.04 ...
1
vote
0answers
12 views

Tmpfs with overflow on disk?

I'm looking for a way to have a tmpfs-like file system that can be unlimited in size, but will use a specified amount of RAM after which the "oversize" data will be stored on another disk-backed ...
1
vote
0answers
682 views

How are ownership and permissions of tmpfs folders created via /etc/fstab determined?

I've created a folder /mnt/ramdisk. I've got the following line in /etc/fstab to create the ramdisk at startup and mount it to /mnt/ramdisk: tmpfs /mnt/ramdisk tmpfs size=4096M,mode=0777,...
1
vote
0answers
68 views

unlimited tmpfs

How to have the advantages of tmpfs and not be limited to its small size? I'm thinking of a shell script that runs as a daemon, monitors RAM and adds more swap files in specified folder, when memory ...