filesystem mount problem

[Cy Schubert]

On July 21, 2019 1:44:13 PM PDT, Ian Lepore <ian at freebsd.org> wrote:
>On Sun, 2019-07-21 at 15:07 -0400, AN wrote:
>> Hi:
>> 
>> FreeBSD FreeBSD_13 13.0-CURRENT FreeBSD 13.0-CURRENT #102 r350187:
>> Sat Jul 
>> 20 19:04:30 EDT 2019 
>> root at FreeBSD_13:/usr/obj/usr/src/amd64.amd64/sys/MYKERNEL  amd64
>> 1300036
>> 
>> I would appreciate some help with the following problem.
>> 
>> /etc/fstab:
>> # Device	Mountpoint	FStype	Options	Dump	Pass#
>> /dev/ada0p2	none		swap	sw	0	0
>> /dev/ada0p3	/		ufs	rw	1	1
>> linprocfs   /compat/linux/proc	linprocfs	rw	0	0
>> tmpfs    /compat/linux/dev/shm	tmpfs	rw,mode=1777	0	
>> 0
>> 
>> 
>> # df -h
>> Filesystem     Size    Used   Avail Capacity  Mounted on
>> /dev/ada0p3    428G    245G    149G    62%    /
>> devfs          1.0K    1.0K      0B   100%    /dev
>> linprocfs      4.0K    4.0K      0B   100%    /compat/linux/proc
>> tmpfs           47G    4.0K     47G     0%    /compat/linux/dev/shm
>> tmpfs           20M    604K     19M     3%    /tmp
>> 
>> I don't understand why the /tmp is being mounted.  It is causing
>> problems 
>> because when I try to run portupgrade it fails for lack of space.  If
>> I 
>> forcibly unmount it everything breaks.
>> 
>> # umount -v /tmp
>> umount: unmount of /tmp failed: Device busy
>> [root at FreeBSD_13 ~]# umount -vf /tmp
>> tmpfs: unmount from /tmp
>> [root at FreeBSD_13 ~]# df -h
>> Filesystem     Size    Used   Avail Capacity  Mounted on
>> /dev/ada0p3    428G    245G    149G    62%    /
>> devfs          1.0K    1.0K      0B   100%    /dev
>> linprocfs      4.0K    4.0K      0B   100%    /compat/linux/proc
>> tmpfs           47G    4.0K     47G     0%    /compat/linux/dev/shm
>> [root at FreeBSD_13 ~]# vinagre
>> Unable to init server: Could not connect to 127.0.0.1: Connection
>> refused
>> 
>> (vinagre:27111): Gtk-WARNING **: 15:04:21.599: cannot open display:
>> :0
>> 
>> Any help would be appreciated, thanks in advance.
>> 
>
>The problem isn't that /tmp is tmpfs, the problem is that it's being
>mounted by /etc/rc.d/tmp as a 20MB filesystem because tmpsize="20m" is
>the default.  You could set tmpsize to some bigger value in rc.conf, or
>you can add an explicit mount for /tmp in fstab so that you get the
>full (47G on your system) capacity that's available:
>
> tmpfs /tmp tmpfs rw 0 0
>
>-- Ian
>
>
>_______________________________________________
>freebsd-current at freebsd.org mailing list
>https://lists.freebsd.org/mailman/listinfo/freebsd-current
>To unsubscribe, send any mail to
>"freebsd-current-unsubscribe at freebsd.org"

I've seen clients inadvertently DoS themselves when I was a Solaris admin. Solaris never used limits for tmpfs. 

As to how we arrived at 20m, I recall an OSF/1 course where the instructor intimated that 20m was industry best practice at the time and OSF/1 being BSD. That was a lifetime ago. Maybe it's time to consider a higher default for 2019.

Anticipating a memory constrained embedded argument, people designing products would customize it anyway. 


-- 
Pardon the typos and autocorrect, small keyboard in use.
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX: <cy at FreeBSD.org> Web: http://www.FreeBSD.org

	The need of the many outweighs the greed of the few.