[SOLVED] Latest filesystem update question

dcbdbis · 2011-08-15 23:57:45

So, I allowed pacman to install the filesystem updates a few minutes ago. I had one /etc/fstab.pacnew file.

It had an entry (tmpfs) that my existing fstab lacked. I do a lot of customization to my fstab for a variety of drives I have, but am not familiar with what I would call "system" level fstab entries.

I am requesting that someone "vet" my non- storage specific entries in my fstab to tell me if I need to add something further, or delete a line that has been superseded.

# 
# /etc/fstab: static file system information
#
# <file system>        				<dir>         		<type>    	<options>          								<dump> <pass>

devpts                 				/dev/pts      		devpts    	defaults            								0	0
shm                    				/dev/shm      		tmpfs     	nodev,nosuid        								0	0
tmpfs						/tmp			tmpfs		nodev,nosuid									0	0

Thank you for your time....

Sincerely and respectfully,

Dave

Last edited by dcbdbis (2011-08-16 01:50:33)

graysky · 2011-08-16 00:01:14

Looks fine to me. Here's mine for your reference. See the wiki for more.

tmpfs	/tmp  tmpfs nodev,nosuid,nodiratime,noatime,size=2G,mode=1777	0	0
devpts                 /dev/pts      devpts    defaults            0      0
shm	/dev/shm	tmpfs	nodev,nosuid,size=7G        0      0

karol · 2011-08-16 00:10:23

Some recent changes http://projects.archlinux.org/svntogit/ … 816afa8859

falconindy · 2011-08-16 00:16:00

karol's linked commit sums it up. /dev/shm and /dev/pts mount entries should be removed, and we're recommending that you mount /tmp on tmpfs.

dcbdbis · 2011-08-16 01:50:18

Thank you to all who posted. I rem'd out the /dev/pts and /dev/shm entries and rebooted.

I can confirm that the system came up perfectly normal. After a week or so, then I'll nuke the rem'd out lines......

Again, thank you to all for the responses.

Sincerely and respectfully,

Dave

Last edited by dcbdbis (2011-08-16 01:51:27)

graysky · 2011-08-16 20:26:06

fstab: remove /dev/{shm,pts} add /tmp
/dev/{shm,pts} are dealt with by initrd or rc.sysinit. Making /tmp a tmpfs by default as this is almost always the right thing to do. git-svn-id: file:///srv/svn-packages@132374 eb2447ed-0c53-47e4-bac8-5bc4a241df78

Silly question: how did /dev/shm get created with size=7G on my system? I looked in /etc/rc.sysinit but didn't see it there.

$ df -h|grep shm
shm             7.0G  822M  6.2G  12% /dev/shm

karol · 2011-08-16 20:28:55

graysky wrote:

Silly question: how did /dev/shm get created with size=7G on my system? I looked in /etc/rc.sysinit but didn't see it there.
$ df -h|grep shm
shm             7.0G  822M  6.2G  12% /dev/shm

That's your swap or what?

graysky · 2011-08-16 20:34:50

@k - no swap on this machine. I understand that /tmp is defaulted to 1/2 of physical memory (8/2=4) but how does /dev/shm get to be 7 G?

 df -h
Filesystem      Size  Used Avail Use% Mounted on
udev             10M     0   10M   0% /dev
run              10M  284K  9.8M   3% /run
/dev/sdb1        14G  2.6G   11G  20% /
shm             7.0G   77M  7.0G   2% /dev/shm
tmpfs           4.0G   20K  4.0G   1% /tmp

karol · 2011-08-16 20:48:16

http://mailman.archlinux.org/pipermail/ … 21265.html
Maybe it's a way to discourage? ;P

graysky · 2011-08-16 20:48:56

@bernarcher - I read that, and I don't have it in my /etc/fstab anymore. That's why I'm confused as to what is making it assigned to 7G.

$ cat /etc/fstab
tmpfs /tmp tmpfs nodev,nosuid 0 0
/dev/dvd	/media/dvd  auto    ro,user,noauto,unhide   0      0

/dev/sdb1	/	ext4    defaults,noatime,discard	0       1
/dev/sdb2	/home	ext4    defaults,noatime,discard	0       2
/dev/sda2 	/var	ext4	defaults,relatime	0	1
/dev/sda3 	/boot	ext3	defaults,relatime	0	1
/dev/sda6	        /media/data	ntfs-3g	defaults,umask=002,fmask=113,gid=100,uid=1000	00

bernarcher · 2011-08-16 20:54:33

(Sorry, I inadvertently deleted this post of mine. )

It is gone in my system now after reboot (yet, I updated the kernel in the meantime):

Filesystem                                              Size  Used Avail Use% Mounted on
udev                                                     10M     0   10M   0% /dev
run                                                      10M  220K  9.8M   3% /run
/dev/disk/by-uuid/a077f168-44b7-4efc-95a1-727e22f67e7f   45G  7.7G   35G  19% /
tmpfs                                                   501M  164K  501M   1% /tmp
/dev/sdb5                                                15G  9.1G  6.0G  61% /var
/dev/sdb6                                                51G   31G   17G  65% /home

Only thing which else comes to my mind is that shm is intantiated from initramd.

graysky · 2011-08-16 20:56:44

So I should manually dismount /dev/shm and rebuild my image via mkinitcpio -p linux-ck?

bernarcher · 2011-08-16 20:58:16

It would be worth a try.
BTW. I remember that I for some time explicitely unmounted /dev/shm in my rc.local.

graysky · 2011-08-16 21:04:39

OK... dismounted, rebuilt, and rebooted. I still have /dev/shm but now the size it 1/2 physical memory. I'm not creating it anywhere as far as I know.

Do others still have it upon removing it from fstab?

df -h$ df -h
Filesystem      Size  Used Avail Use% Mounted on
udev             10M     0   10M   0% /dev
run              10M  284K  9.8M   3% /run
/dev/sdb1        14G  2.6G   11G  20% /
shm             4.0G   77M  3.9G   2% /dev/shm
tmpfs           4.0G   28K  4.0G   1% /tmp

karol · 2011-08-16 21:11:05

@graysky
Maybe you should open another thread, as OP had just a quick question.

Yes, I still have /dev/shm the size of 1/2 physical memory but I use swap of exactly this size

[karol@black ~]$ df -h
Filesystem                                              Size  Used Avail Use% Mounted on
udev                                                     10M     0   10M   0% /dev
run                                                      10M  136K  9,9M   2% /run
/dev/disk/by-uuid/bf1d191b-0f0d-4961-bd67-4d023a2e5873  7,3G  3,0G  3,9G  44% /
shm                                                     246M     0  246M   0% /dev/shm
tmpfs                                                   246M   16K  246M   1% /tmp
/dev/sda1                                                99M   16M   79M  17% /boot
/dev/sda4                                                30G   21G  6,9G  76% /home
[karol@black ~]$ free -m
             total       used       free     shared    buffers     cached
Mem:           491        460         30          0          0         42
-/+ buffers/cache:        417         73
Swap:          258         29        228

I'm a bit confused: I have 256 MB swap allocated, but /dev/shm shows 0 MB used, even if I do use 29 Mb according to 'free'.

Last edited by karol (2011-08-16 21:11:45)

Inxsible · 2011-08-16 21:39:20

I have shm mounted as well for 1.9Gs, but my swap size is only 512MB, I gotta look into this as well.

Inxsible · 2011-08-17 03:01:11

Here's my df output

[inxs ~ ]$ df
Filesystem                                             Type      Size  Used Avail Use% Mounted on
udev                                                   devtmpfs   10M     0   10M   0% /dev
run                                                    tmpfs      10M  248K  9.8M   3% /run
/dev/disk/by-uuid/2531f3c1-e139-48c0-bbda-a6650b58eb0c ext4      6.9G  2.3G  4.3G  36% /
shm                                                    tmpfs     1.9G     0  1.9G   0% /dev/shm
tmpfs                                                  tmpfs     1.9G   12K  1.9G   1% /tmp
/dev/sda7                                              reiserfs  4.0G  600M  3.5G  15% /var
/dev/sda6                                              ext4       23G   11G   11G  51% /home
[inxs ~ ]$

tmp -- is half of RAM (4GB) but why is shm mounted again?
Here's free -m

[inxs ~ ]$ free
             total       used       free     shared    buffers     cached
Mem:          3836        470       3365          0         22        140
-/+ buffers/cache:        307       3528
Swap:          516          0        516
[inxs ~ ]$

fsckd · 2011-08-17 03:09:23

IIRC some things need /dev/shm. I don't remember what.

thisoldman · 2011-08-17 04:24:45

Take a look at '/usr/src/linux-3.0-ARCH/Documentation/filesystems/tmpfs.txt'. It helped me understand the fstab changes.

2) glibc 2.2 and above expects tmpfs to be mounted at /dev/shm for POSIX shared memory (shm_open, shm_unlink)...

Also look at lines 21-25 in 'etc/rc.sysinit'.

Last edited by thisoldman (2011-08-17 04:33:36)

bernarcher · 2011-08-17 05:46:17

Thanks thisoldman, this was the info I was looking for.

BTW: Just discovered that I had /dev/shm still unmounted in my rc.local. No idea how this crept in again. But it had no negative effects up to now.

Arch Linux

#1 2011-08-15 23:57:45

[SOLVED] Latest filesystem update question

#2 2011-08-16 00:01:14

Re: [SOLVED] Latest filesystem update question

#3 2011-08-16 00:10:23

Re: [SOLVED] Latest filesystem update question

#4 2011-08-16 00:16:00

Re: [SOLVED] Latest filesystem update question

#5 2011-08-16 01:50:18

Re: [SOLVED] Latest filesystem update question

#6 2011-08-16 20:26:06

Re: [SOLVED] Latest filesystem update question

#7 2011-08-16 20:28:55

Re: [SOLVED] Latest filesystem update question

#8 2011-08-16 20:34:50

Re: [SOLVED] Latest filesystem update question

#9 2011-08-16 20:48:16

Re: [SOLVED] Latest filesystem update question

#10 2011-08-16 20:48:56

Re: [SOLVED] Latest filesystem update question

#11 2011-08-16 20:54:33

Re: [SOLVED] Latest filesystem update question

#12 2011-08-16 20:56:44

Re: [SOLVED] Latest filesystem update question

#13 2011-08-16 20:58:16

Re: [SOLVED] Latest filesystem update question

#14 2011-08-16 21:04:39

Re: [SOLVED] Latest filesystem update question

#15 2011-08-16 21:11:05

Re: [SOLVED] Latest filesystem update question

#16 2011-08-16 21:39:20

Re: [SOLVED] Latest filesystem update question

#17 2011-08-17 03:01:11

Re: [SOLVED] Latest filesystem update question

#18 2011-08-17 03:09:23

Re: [SOLVED] Latest filesystem update question

#19 2011-08-17 04:24:45

Re: [SOLVED] Latest filesystem update question

#20 2011-08-17 05:46:17

Re: [SOLVED] Latest filesystem update question

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