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Recently I found /run/lock and /run/shm folders to be missing.

I tried to recover some files with a mounted disk, I now know that this may caused the harm. So unaware what to do, I created these directories by myself.

Now I looked up the command df -h and saw this output:

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda6             913G   69G  798G   8% /
udev                  5,9G  4,0K  5,9G   1% /dev
tmpfs                 2,4G  872K  2,4G   1% /run
none                  5,0M     0  5,0M   0% /run/lock
none                  5,9G  2,1M  5,9G   1% /run/shm
/dev/sda1             915M  358M  509M  42% /boot

I didn't know there were such file systems, how can I mount them in again? Is this something harmful?

I also saw that I have high I/O with my Journal jbd2/sda6-8 always around 40%, has this something to do with this?

share|improve this question
This should clear all your doubts: What are “/run/lock” and “/run/shm” used for? – saji89 Apr 23 '13 at 9:05
Possible duplicate of:… – saji89 Apr 23 '13 at 9:06
@saji89 I disagree slightly. I'm perhaps biased, having written an answer, but I was approaching this as more of a "Why is their filesystem listed as none? Are they broken?" than a "what are they?" – Oli Apr 23 '13 at 9:13
@Oli, I feel that this particular information will better serve as a good addon to the answer already here:… His question was: "I didn't know there were such file systems, how can I mount them in again? Is this something harmful?". looks like the other question definitely answers that. – saji89 Apr 23 '13 at 9:16
Yeah thanks for the link anyway! It's always good to understand what something does. – Dan Lee Apr 23 '13 at 9:19
up vote 3 down vote accepted

I think df is getting thrown by the lack of specified device. If you look with mount, you'll see that the filesystem is definitely tmpfs.

$ df -h | grep run
tmpfs                          4.8G  1.4M  4.8G   1% /run
none                           5.0M     0  5.0M   0% /run/lock
none                            12G  4.9M   12G   1% /run/shm
none                           100M  8.0K  100M   1% /run/user

$ mount | grep run
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755)
rpc_pipefs on /run/rpc_pipefs type rpc_pipefs (rw)

I would guess that because tmpfs is a ram-disk that you don't actually need to specify a block level object to "mount".

I would certainly welcome people correct me if that assumption is incorrect but for your case there is nothing to worry about. They're not missing, they're just mounted funny... And that just happens to be the way all my Ubuntu computers here are also set up. Panic not.

share|improve this answer
Cool, thanks for the clarification. Now I can calm down :-). Only problem left is the Journal problem, but that seems to be quite another matter now. – Dan Lee Apr 23 '13 at 9:16
@DanLee Almost certainly unrelated to this. I'd start a new question about it if I were you. – Oli Apr 23 '13 at 9:21
Yeah you're right! That's why I didn't want to ask you more about that in this topic. – Dan Lee Apr 23 '13 at 9:22

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