Mount point bind issues Post: 302994511

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Top Forums UNIX for Beginners Questions & Answers Mount point bind issues Post 302994511 by drysdalk on Thursday 23rd of March 2017 04:05:26 PM

03-23-2017

Registered User

Hi,

Great, glad you got that sorted. One last thing that may disappoint, however. If you're doing this because you're hoping to basically add the free space of the /prod/OpenCSS filesystem to the existing /var/lib/pgsql filesystem...well, then you're out of luck.

That's not how bind mounts work, or what they're for. They're purely for providing an alternative path to access the same content in multiple places, and nothing else. The free space you'll see will be that of the original filesystem, since all the calls are being routed through to the original filesystem - the new one (in your scenario) isn't actually going to be used at all.

For example, watch what happens if I do a bind mount of my /boot filesystem to a new directory, /mnt/misc:

Code:

$ df -h /boot
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       240M  110M  114M  49% /boot
$ df -h /mnt/misc
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2       225G  132G   82G  62% /
$ sudo /bin/mount --bind /boot /mnt/misc
$ df -h /boot
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       240M  110M  114M  49% /boot
$ df -h /mnt/misc
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       240M  110M  114M  49% /mnt/misc
$ sudo /bin/umount /mnt/misc
$ df -h /boot
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       240M  110M  114M  49% /boot
$ df -h /mnt/misc
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda2       225G  132G   82G  62% /
$

So as you can see, the disc space and all other properties of the bind mount destination are the same as the source, since in reality all you're doing is providing an additional path for accessing the source, and nothing more.

Hope this helps.

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LEARN ABOUT HPUX

quotaon

quotaon(1M)															       quotaon(1M)

NAME

       quotaon, quotaoff - turn HFS file system quotas on and off

SYNOPSIS

       filesystem ...

       filesystem ...

   Remarks
       These  commands	are  provided for compatibility only.  Their use is neither required nor recommended because and enable and disable quotas
       cleanly (see mount(1M)).  See below for more information.

DESCRIPTION

       The command enables quotas on one or more file systems.	Group quotas cannot be enabled on HFS file systems.

       The command disables quotas on one or more HFS file systems.

       filesystem is either the name of the mount point of the file system, or the name of the block device containing the file system.  The  file
       systems	specified  must  be currently mounted in order to turn quotas on or off.  Also, the file system quota files, (for user quotas) and
       (for group quotas) must be present in the root directory of each specified file system.

       These commands will update the appropriate entries in to indicate that quotas are on or off for each file system.

       When enabling quotas interactively after boot time, the command should be run immediately afterward (see below).

       Use (see mount(1M)) to determine whether quotas are enabled on mounted file systems.

   Options
       The following options affect the behavior described above.

	      Obtain the
		     filesystem list from using entries of type and (or with the option, for  user  quotas  and  option,  for  group  quotas  (see
		     fstab(4)).

	      Turn on or off group quotas only.

	      Turn on or off user quotas (the default) only.

	      Generate a message for each file system affected.

EXTERNAL INFLUENCES

   Environment Variables
       determines the language in which messages are displayed.

       If is not specified in the environment or is set to the empty string, the value of is used as a default for each unspecified or empty vari-
       able.  If is not specified or is set to the empty string, a default of "C" (see lang(5)) is used instead of

       If any internationalization variable contains an invalid setting, behaves as if all internationalization variables are  set  to	"C".   See
       environ(5).

   International Code Set Support
       Single and multi-byte character code sets are supported.

WARNINGS

       Using  to  disable quotas on a file system causes the system to discontinue tracking quotas for that file system, and marks the flag in the
       superblock (see fsclean(1M)).  This in turn, forces a the next time the system is booted.  Since quotas are enabled and disabled cleanly by
       and anyway, the use of and is generally discouraged.

AUTHOR

       Disk quotas were developed by the University of California, Berkeley, Sun Microsystems, Inc., and HP.

FILES

       Static information about the file systems

       Mount file system table

       Group and user quota statistics static storage for a
				file  system  respectively,  where  directory  is  the	root  of  the file system as specified to the command (see
				mount(1M)).

SEE ALSO

       fsclean(1M), mount(1M), quotacheck(1M), quotacheck_hfs(1M), quotacheck_vxfs(1M), quota(5).

																       quotaon(1M)

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