Re: [CentOS] Does devtmps and tmpfs use underlying hard disk storage or Physical Memory (RAM)
On Fri, Apr 19, 2019 at 8:51 PM Kaushal Shriyan wrote: > Does devtmpfs and tmpfs use underlying hard disk storage or does it uses > Physical Memory (RAM). What is the purpose of devtmpfs which is mounted on > /dev, tmpfs mounted on /dev/shm and so on and so forth. What is the > difference between devtmpfs and tmpfs? tmpfs *tries* not to use disk. /dev/shm is great to use as *fast* large scratch space. Have used /dev/shm to greatly speed up a daily process to parse web server logs. Didn’t /seem/ like the process was IO or disk bound. . . Until I threw the logs in /dev/shm and a multi hour process completed in 1/4 the time. Have used /dev/shm for other “things”. There is /dev/ram# which should never be written to disk, but has the problem of being much much smaller (4MB iirc) and no filesystem access. So you’d have to `mkfs /dev/ram#` and then `mount /dev/ram# /somewhere`. Once used /dev/ram# for USB camera “security system”. The camera gave large-ish files and couldn’t figure out how to get the camera app to output to stdOut to then shrink the file to a tiny jpeg with pipes. So had the camera write to /dev/ram and then read the file from /dev/ram through `convert` or something to jpeg-ify the image. Greatly sped up (like 2-3x) how often that could save images. Happy learning how to Linux. (: ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
[CentOS] CentOS-announce Digest, Vol 170, Issue 5
Send CentOS-announce mailing list submissions to centos-annou...@centos.org To subscribe or unsubscribe via the World Wide Web, visit https://lists.centos.org/mailman/listinfo/centos-announce or, via email, send a message with subject or body 'help' to centos-announce-requ...@centos.org You can reach the person managing the list at centos-announce-ow...@centos.org When replying, please edit your Subject line so it is more specific than "Re: Contents of CentOS-announce digest..." Today's Topics: 1. CESA-2019:0778 Moderate CentOS 7 java-11-openjdk Security Update (Johnny Hughes) 2. CESA-2019:0775 Important CentOS 7 java-1.8.0-openjdk Security Update (Johnny Hughes) 3. CESA-2019:0774 Important CentOS 6 java-1.8.0-openjdk Security Update (Johnny Hughes) -- Message: 1 Date: Fri, 19 Apr 2019 18:39:15 + From: Johnny Hughes To: centos-annou...@centos.org Subject: [CentOS-announce] CESA-2019:0778 Moderate CentOS 7 java-11-openjdk Security Update Message-ID: <20190419183915.ga30...@bstore1.rdu2.centos.org> Content-Type: text/plain; charset=us-ascii CentOS Errata and Security Advisory 2019:0778 Moderate Upstream details at : https://access.redhat.com/errata/RHSA-2019:0778 The following updated files have been uploaded and are currently syncing to the mirrors: ( sha256sum Filename ) x86_64: b6a9b7941571bb174ce804b64d2ad94cc24f6af4e201196494c097de4a4ffaa8 java-11-openjdk-11.0.3.7-0.el7_6.i686.rpm b9b48cb489ef67b11e6cec5a4dfc55fd1cb89c046401543e671fea324cb99813 java-11-openjdk-11.0.3.7-0.el7_6.x86_64.rpm d1dad21be37df857e6a933c63ebee1a270991a8da22f3720055ecd7abda5900c java-11-openjdk-debug-11.0.3.7-0.el7_6.i686.rpm ef81f3232faf0f1d10b5ef447458ad9ea7cc532935cafa94c3e10e408ce2bd37 java-11-openjdk-debug-11.0.3.7-0.el7_6.x86_64.rpm 777e5539a1e0b16f8a823cb2db98c5f430b601c186a3e572aff1e0e43c48fcaa java-11-openjdk-demo-11.0.3.7-0.el7_6.i686.rpm 4a48999506ff914e54b9860c3082a2585d0969cdb4fa496c02bede5db4d52ee7 java-11-openjdk-demo-11.0.3.7-0.el7_6.x86_64.rpm a4f9b7863c331ac98b4d319fc1517af72144525831cf88ff5c8aefc39deb5648 java-11-openjdk-demo-debug-11.0.3.7-0.el7_6.i686.rpm 40030f978ab8451fb532dbcb4b407da17d5004ca88ef338911efdadb78c88b3b java-11-openjdk-demo-debug-11.0.3.7-0.el7_6.x86_64.rpm 03bcebe31f9891b540ef7274187192ac8d2b678fe2447370cba497d5890ff826 java-11-openjdk-devel-11.0.3.7-0.el7_6.i686.rpm 0e8eba5d04de047404e67f07318b74eb188c771141404576a969ce5e03ca3d86 java-11-openjdk-devel-11.0.3.7-0.el7_6.x86_64.rpm 3680df303d48ca74cae964d46e8f73b2a3b4f48f540c4d836c8ac459809e1f92 java-11-openjdk-devel-debug-11.0.3.7-0.el7_6.i686.rpm 09fded1933bb6c86075496f5896df626a63eaeee353a549e89ff7bb797f84d21 java-11-openjdk-devel-debug-11.0.3.7-0.el7_6.x86_64.rpm ff08e7ab4253c3ab7278ef6944926fb14b440b989b4d4304c759502217e931ff java-11-openjdk-headless-11.0.3.7-0.el7_6.i686.rpm 49fba40a09f2410abe59771ccd81fb65b6c16087e52f3555b10a51f52a7a0076 java-11-openjdk-headless-11.0.3.7-0.el7_6.x86_64.rpm 2ef67928c40a035d3c007aea2ef32c3dbaa8c17a78244e5ff15a0c0430126d37 java-11-openjdk-headless-debug-11.0.3.7-0.el7_6.i686.rpm c89a013731229814e930d6a9bec5c0ed21962acbca025d4730110648da402c5a java-11-openjdk-headless-debug-11.0.3.7-0.el7_6.x86_64.rpm d298c2948e78108b2a3b9de4d4ce7e0e6b3ba86a0b81f3ec0d057551c1020779 java-11-openjdk-javadoc-11.0.3.7-0.el7_6.i686.rpm 0dca6e3aa6af3b9015e9095dae148f92379a8d6b3d93d8de4044eba80c031e75 java-11-openjdk-javadoc-11.0.3.7-0.el7_6.x86_64.rpm b54b3bc176ba870cdea2ff46fe3c29dd3cc4d8e580ad87c7e3e43fa3f87bf0e3 java-11-openjdk-javadoc-debug-11.0.3.7-0.el7_6.i686.rpm 9b235a780b48395b9693669389a5f56dd531d2c59bc7ed94f26e17f597310d74 java-11-openjdk-javadoc-debug-11.0.3.7-0.el7_6.x86_64.rpm 796aa75e299bcda8abad4d95197767e6b97b94209f5a8b2fbd9dc77ba4f45ea6 java-11-openjdk-javadoc-zip-11.0.3.7-0.el7_6.i686.rpm 4da49197fd3b21c85ee232cc4be98b5bf9c8e8f0df074b9a35e09cdc4162b547 java-11-openjdk-javadoc-zip-11.0.3.7-0.el7_6.x86_64.rpm bc98c45b572e4decbea0b325fb7dadc4a63adb1d76f97c2f59b88f166d5a7302 java-11-openjdk-javadoc-zip-debug-11.0.3.7-0.el7_6.i686.rpm 86e3011db798495d044f6da0f80cdae0a343e81f9d0556cd721238a7c98be745 java-11-openjdk-javadoc-zip-debug-11.0.3.7-0.el7_6.x86_64.rpm 73879ef06cec69705ee5e7ac112faa64eef5861b74e66c6f47b9106bdba0aba1 java-11-openjdk-jmods-11.0.3.7-0.el7_6.i686.rpm 8b774cd47ed4d154fb2c7def5a08e1bc4d9b6ed7abe9e31bc2c2cc1501ac7c44 java-11-openjdk-jmods-11.0.3.7-0.el7_6.x86_64.rpm 0565f7b2853bacb2cb8e3e04bf6aa6da2ac9efc9fff36fe9a423e4727e3c9946 java-11-openjdk-jmods-debug-11.0.3.7-0.el7_6.i686.rpm 6be04d6605ab46e7822832cac298387a02d7128e0425a8cf196e924d5273d638 java-11-openjdk-jmods-debug-11.0.3.7-0.el7_6.x86_64.rpm 827a9288281a4f2c0ff2ed5a34ef512817e2b6f5e4c4abb8bc85181596e859fd java-11-openjdk-src-11.0.3.7-0.el7_6.i686.rpm 83f3b61b23f52ea8a71863f0f1c6f94707a107e387d85a560a498c79af3ee3b6 java-11-openjd
[CentOS] Re: Does devtmps and tmpfs use underlying hard disk storage or Physical Memory (RAM)
On Sat, 20 Apr 2019 02:51, Kaushal Shriyan wrote:
Hi,
I am running the below command on CentOS Linux release 7.6.1810 (Core)
# df -hT --total
Filesystem Type Size Used Avail Use% Mounted on
/dev/xvda1 xfs 150G 8.0G 143G 6% /
devtmpfs devtmpfs 7.8G 0 7.8G 0% /dev
tmpfs tmpfs 7.8G 0 7.8G 0% /dev/shm
tmpfs tmpfs 7.8G 817M 7.0G 11% /run
tmpfs tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup
tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/995
tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/1000
total - 185G 8.8G 176G 5% -
#
Does devtmpfs and tmpfs use underlying hard disk storage or does it uses
Physical Memory (RAM). What is the purpose of devtmpfs which is mounted on
/dev, tmpfs mounted on /dev/shm and so on and so forth. What is the
difference between devtmpfs and tmpfs?
I will appreciate if anyone can help me understand the above output.
"Per Principa" are both, - devtmpfs and tmpfs - RAM based, BUT, pages
of RAM can be stored on disk/ssd via use of swap, same as any other
RAM usage.
Whats the difference between devtmpfs and tmpfs?
For the normal user none.
Original toughts for devtmpfs where based where based around reducing
the needed memory per entry, because /dev {excluding /dev/shm}
should only contain device-nodes, or links witch both are stored as
directory-entries without data-inodes-entries, later direcories where
included.
While tmpfs is similar to other on-disk-filesystems capable of storing
files with a size greater than zero. "/dev/shm" was the first in-ram-fs
available to the casual user without extra work.
What is the difference with the actual kernels?
I would have to look into the kernel source, as my detail knowlegde
of the matter is dated.
- Yamaban.
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Re: [CentOS] Does devtmps and tmpfs use underlying hard disk storage or Physical Memory (RAM)
On Sat, 2019-04-20 at 06:21 +0530, Kaushal Shriyan wrote: > Hi, > > I am running the below command on CentOS Linux release 7.6.1810 (Core) > > # df -hT --total > Filesystem Type Size Used Avail Use% Mounted on > /dev/xvda1 xfs 150G 8.0G 143G 6% / > devtmpfs devtmpfs 7.8G 0 7.8G 0% /dev > tmpfs tmpfs 7.8G 0 7.8G 0% /dev/shm > tmpfs tmpfs 7.8G 817M 7.0G 11% /run > tmpfs tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup > tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/995 > tmpfs tmpfs 1.6G 0 1.6G 0% /run/user/1000 > total - 185G 8.8G 176G 5% - > # > > Does devtmpfs and tmpfs use underlying hard disk storage or does it uses > Physical Memory (RAM). It uses RAM, that's what 'tmpfs' is, a temporary RAM filesystem. > What is the purpose of devtmpfs which is mounted on > /dev, tmpfs mounted on /dev/shm and so on and so forth. What is the > difference between devtmpfs and tmpfs? devtmpfs is a kernel maintained filesystem of automated device nodes. tmpfs is a RAM disk. > > I will appreciate if anyone can help me understand the above output. Google really is your friend here. P. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
