1

I migrate 10 CentOS6 to CentOS7. For six month all the servers are working great aside from one. The DB that is running on is having problems every couple of days, the only different from that server and others is when I do 'df', I see a lot of 'tmpfs':

Filesystem                Size  Used Avail Use% Mounted on
/dev/mapper/os-root       2.0G  159M  1.8G   8% /
devtmpfs                  7.8G     0  7.8G   0% /dev
tmpfs                     7.8G     0  7.8G   0% /dev/shm
tmpfs                     7.8G  146M  7.7G   2% /run
tmpfs                     7.8G     0  7.8G   0% /sys/fs/cgroup
/dev/mapper/os-usr        5.9G  2.5G  3.4G  42% /usr
/dev/mapper/os-tmp        2.0G   51M  1.9G   3% /tmp
/dev/mapper/os-var        5.9G  553M  5.4G  10% /var
/dev/mapper/bck-bck       300G  181G  120G  61% /bck
/dev/mapper/db-db       200G  156G   45G  78% /db
/dev/sda1                 497M  169M  329M  34% /boot
/dev/mapper/os-home       997M   42M  956M   5% /home
10.10.10.99:/cav/files/c2p  406G  200G  186G  52% /db/temp
tmpfs                     1.6G     0  1.6G   0% /run/user/0
tmpfs                     1.6G     0  1.6G   0% /run/user/791803772
tmpfs                     1.6G     0  1.6G   0% /run/user/791802700
tmpfs                     1.6G     0  1.6G   0% /run/user/791802723
tmpfs                     1.6G     0  1.6G   0% /run/user/791802745
/dev/mapper/db-db.snap  200G  156G   45G  78% /db.snap
tmpfs                     1.6G     0  1.6G   0% /run/user/791802789
tmpfs                     1.6G     0  1.6G   0% /run/user/791803776
tmpfs                     1.6G     0  1.6G   0% /run/user/791801124
tmpfs                     1.6G     0  1.6G   0% /run/user/791803812
tmpfs                     1.6G     0  1.6G   0% /run/user/791803678
tmpfs                     1.6G     0  1.6G   0% /run/user/791802829
tmpfs                     1.6G     0  1.6G   0% /run/user/791801264
tmpfs                     1.6G     0  1.6G   0% /run/user/791801198

My question is, anyone know what is all these tempfs?

Thanks in advance

Adrian

7

From unix.stackexchange.com

Here is a snippet from that post:

/run/user/$uid is created by pam_systemd and used for storing files used by running processes for that user. These might be things such as your keyring daemon, pulseaudio, etc.

Prior to systemd, these applications typically stored their files in /tmp. They couldn't use a location in /home/$user as home directories are often mounted over network filesystems, and these files should not be shared among hosts. /tmp was the only location specified by the FHS which is local, and writable by all users.

So systemd came along and created /run/user/$uid. This directory is local to the system and only accessible by the target user.

To address your concern, this shouldn't really be a problem unless users are consuming a lot of space in /tmp which is really swap backed memory. Thanks goes to Patrick for that great answer.

| improve this answer | |
  • No problem. I was actually looking for a better explanation of that new behavior myself. It was introduced in CentOS 7.2. – Aaron Jan 10 '16 at 17:12

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