Does order of mount operations matter when mounting into an existing mountpoint?
The question Best practice when mounting a new disk within an existing mount?
inspired me to ask this follow-up question:
The other question asked whether it is ok to
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
so that /home/mythtv is a mountpoint within the mountpoint
/home. (spoiler: Yes, it is perfectly ok.).
What if I'd change the order of commands to
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
Will that yield the same result or will /home/mythtv be hidden by /home?
I assume /home contains an (empty) directory /home/mythtv.
mount
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
add a comment |
The question Best practice when mounting a new disk within an existing mount?
inspired me to ask this follow-up question:
The other question asked whether it is ok to
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
so that /home/mythtv is a mountpoint within the mountpoint
/home. (spoiler: Yes, it is perfectly ok.).
What if I'd change the order of commands to
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
Will that yield the same result or will /home/mythtv be hidden by /home?
I assume /home contains an (empty) directory /home/mythtv.
mount
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
add a comment |
The question Best practice when mounting a new disk within an existing mount?
inspired me to ask this follow-up question:
The other question asked whether it is ok to
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
so that /home/mythtv is a mountpoint within the mountpoint
/home. (spoiler: Yes, it is perfectly ok.).
What if I'd change the order of commands to
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
Will that yield the same result or will /home/mythtv be hidden by /home?
I assume /home contains an (empty) directory /home/mythtv.
mount
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
The question Best practice when mounting a new disk within an existing mount?
inspired me to ask this follow-up question:
The other question asked whether it is ok to
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
so that /home/mythtv is a mountpoint within the mountpoint
/home. (spoiler: Yes, it is perfectly ok.).
What if I'd change the order of commands to
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
Will that yield the same result or will /home/mythtv be hidden by /home?
I assume /home contains an (empty) directory /home/mythtv.
mount
mount
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
asked Jan 4 at 11:08
PerlDuckPerlDuck
7,02611535
7,02611535
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Yes, it matters! Your first example:
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
is the only right way, when mounting you must respect the tree order.
In your second example,
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
If we are assuming /home/mythtv exists on the filesystem, it is gonna mount it with no problem, but after you mount the second volume you won't be able to access the first one anymore.
This is because you let the system mount sdb2 on an existing path at /home/mythtv. When you mount on /home/, you are telling your system to mount it on the /home path which also exists but is going to "cover" existing mount point. They are both mounted, but when you type cd /home/mythtv, Bash takes you to sdb1:/home/mythtv instead sdb2:/home/mythtv because they are different paths.
I hope the explanation is clear. If not, please ask in the comments, I'll try to get it to you more clearly.
Update
as per @mook765's comment, the order is important also in the fstab files:
The fstab file is read up to down while mounting, and down to up when umounting. In another case, if you try to umount /home before /home/mythtv mount will tell you the /home resource is busy because you have the /home/mythtv mounted and it cannot handle it.
edited Jan 4 at 13:41
Dan
7,10934573
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
2
@PerlDuck This is also important for/etc/fstab, line order matters.
– mook765
Jan 4 at 11:37
1
Yes Absolutely, @mook765 say the true, fstab file when mount is read up to down, and when umount down to up, in other case if you try to umount /home before /home/mythtv mount will say to you the /home resource is busy, because have the /home/mythtv mounted and cannot handle it.
– AtomiX84
Jan 4 at 11:47
In which cases would/etc/fstabbe used for unmounting? The only thing I could think of isumount -a, but that command looks at what's actually mounted, not/etc/fstab.
– kasperd
Jan 4 at 16:02
by reading here seems it also used by umount: man7.org/linux/man-pages/man5/fstab.5.html, anyway after thinking a while on this (if you can confirm to me) the umount go to read the fstab when you invoke: umount /mount/point. But I repeat, may I misunderstanding the process of umount, the mount I'm sure is gonna to work like I had describe.
– AtomiX84
Jan 4 at 18:44
Up to down? You mean bottom up or top down???
– FreeSoftwareServers
Jan 4 at 21:23
add a comment |
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1 Answer
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active
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1 Answer
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oldest
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Yes, it matters! Your first example:
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
is the only right way, when mounting you must respect the tree order.
In your second example,
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
If we are assuming /home/mythtv exists on the filesystem, it is gonna mount it with no problem, but after you mount the second volume you won't be able to access the first one anymore.
This is because you let the system mount sdb2 on an existing path at /home/mythtv. When you mount on /home/, you are telling your system to mount it on the /home path which also exists but is going to "cover" existing mount point. They are both mounted, but when you type cd /home/mythtv, Bash takes you to sdb1:/home/mythtv instead sdb2:/home/mythtv because they are different paths.
I hope the explanation is clear. If not, please ask in the comments, I'll try to get it to you more clearly.
Update
as per @mook765's comment, the order is important also in the fstab files:
The fstab file is read up to down while mounting, and down to up when umounting. In another case, if you try to umount /home before /home/mythtv mount will tell you the /home resource is busy because you have the /home/mythtv mounted and it cannot handle it.
edited Jan 4 at 13:41
Dan
7,10934573
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
2
@PerlDuck This is also important for/etc/fstab, line order matters.
– mook765
Jan 4 at 11:37
1
Yes Absolutely, @mook765 say the true, fstab file when mount is read up to down, and when umount down to up, in other case if you try to umount /home before /home/mythtv mount will say to you the /home resource is busy, because have the /home/mythtv mounted and cannot handle it.
– AtomiX84
Jan 4 at 11:47
In which cases would/etc/fstabbe used for unmounting? The only thing I could think of isumount -a, but that command looks at what's actually mounted, not/etc/fstab.
– kasperd
Jan 4 at 16:02
by reading here seems it also used by umount: man7.org/linux/man-pages/man5/fstab.5.html, anyway after thinking a while on this (if you can confirm to me) the umount go to read the fstab when you invoke: umount /mount/point. But I repeat, may I misunderstanding the process of umount, the mount I'm sure is gonna to work like I had describe.
– AtomiX84
Jan 4 at 18:44
Up to down? You mean bottom up or top down???
– FreeSoftwareServers
Jan 4 at 21:23
add a comment |
Yes, it matters! Your first example:
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
is the only right way, when mounting you must respect the tree order.
In your second example,
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
If we are assuming /home/mythtv exists on the filesystem, it is gonna mount it with no problem, but after you mount the second volume you won't be able to access the first one anymore.
This is because you let the system mount sdb2 on an existing path at /home/mythtv. When you mount on /home/, you are telling your system to mount it on the /home path which also exists but is going to "cover" existing mount point. They are both mounted, but when you type cd /home/mythtv, Bash takes you to sdb1:/home/mythtv instead sdb2:/home/mythtv because they are different paths.
I hope the explanation is clear. If not, please ask in the comments, I'll try to get it to you more clearly.
Update
as per @mook765's comment, the order is important also in the fstab files:
The fstab file is read up to down while mounting, and down to up when umounting. In another case, if you try to umount /home before /home/mythtv mount will tell you the /home resource is busy because you have the /home/mythtv mounted and it cannot handle it.
edited Jan 4 at 13:41
Dan
7,10934573
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
2
@PerlDuck This is also important for/etc/fstab, line order matters.
– mook765
Jan 4 at 11:37
1
Yes Absolutely, @mook765 say the true, fstab file when mount is read up to down, and when umount down to up, in other case if you try to umount /home before /home/mythtv mount will say to you the /home resource is busy, because have the /home/mythtv mounted and cannot handle it.
– AtomiX84
Jan 4 at 11:47
In which cases would/etc/fstabbe used for unmounting? The only thing I could think of isumount -a, but that command looks at what's actually mounted, not/etc/fstab.
– kasperd
Jan 4 at 16:02
by reading here seems it also used by umount: man7.org/linux/man-pages/man5/fstab.5.html, anyway after thinking a while on this (if you can confirm to me) the umount go to read the fstab when you invoke: umount /mount/point. But I repeat, may I misunderstanding the process of umount, the mount I'm sure is gonna to work like I had describe.
– AtomiX84
Jan 4 at 18:44
Up to down? You mean bottom up or top down???
– FreeSoftwareServers
Jan 4 at 21:23
add a comment |
Yes, it matters! Your first example:
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
is the only right way, when mounting you must respect the tree order.
In your second example,
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
If we are assuming /home/mythtv exists on the filesystem, it is gonna mount it with no problem, but after you mount the second volume you won't be able to access the first one anymore.
This is because you let the system mount sdb2 on an existing path at /home/mythtv. When you mount on /home/, you are telling your system to mount it on the /home path which also exists but is going to "cover" existing mount point. They are both mounted, but when you type cd /home/mythtv, Bash takes you to sdb1:/home/mythtv instead sdb2:/home/mythtv because they are different paths.
I hope the explanation is clear. If not, please ask in the comments, I'll try to get it to you more clearly.
Update
as per @mook765's comment, the order is important also in the fstab files:
The fstab file is read up to down while mounting, and down to up when umounting. In another case, if you try to umount /home before /home/mythtv mount will tell you the /home resource is busy because you have the /home/mythtv mounted and it cannot handle it.
edited Jan 4 at 13:41
Dan
7,10934573
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
Yes, it matters! Your first example:
mount /dev/sdb1 /home
mount /dev/sdb2 /home/mythtv
is the only right way, when mounting you must respect the tree order.
In your second example,
mount /dev/sdb2 /home/mythtv
mount /dev/sdb1 /home
If we are assuming /home/mythtv exists on the filesystem, it is gonna mount it with no problem, but after you mount the second volume you won't be able to access the first one anymore.
This is because you let the system mount sdb2 on an existing path at /home/mythtv. When you mount on /home/, you are telling your system to mount it on the /home path which also exists but is going to "cover" existing mount point. They are both mounted, but when you type cd /home/mythtv, Bash takes you to sdb1:/home/mythtv instead sdb2:/home/mythtv because they are different paths.
I hope the explanation is clear. If not, please ask in the comments, I'll try to get it to you more clearly.
Update
as per @mook765's comment, the order is important also in the fstab files:
The fstab file is read up to down while mounting, and down to up when umounting. In another case, if you try to umount /home before /home/mythtv mount will tell you the /home resource is busy because you have the /home/mythtv mounted and it cannot handle it.
edited Jan 4 at 13:41
Dan
7,10934573
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
edited Jan 4 at 13:41
Dan
7,10934573
edited Jan 4 at 13:41
Dan
7,10934573
edited Jan 4 at 13:41
Dan
7,10934573
7,10934573
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
answered Jan 4 at 11:18
AtomiX84AtomiX84
955111
955111
2
@PerlDuck This is also important for/etc/fstab, line order matters.
– mook765
Jan 4 at 11:37
1
Yes Absolutely, @mook765 say the true, fstab file when mount is read up to down, and when umount down to up, in other case if you try to umount /home before /home/mythtv mount will say to you the /home resource is busy, because have the /home/mythtv mounted and cannot handle it.
– AtomiX84
Jan 4 at 11:47
In which cases would/etc/fstabbe used for unmounting? The only thing I could think of isumount -a, but that command looks at what's actually mounted, not/etc/fstab.
– kasperd
Jan 4 at 16:02
by reading here seems it also used by umount: man7.org/linux/man-pages/man5/fstab.5.html, anyway after thinking a while on this (if you can confirm to me) the umount go to read the fstab when you invoke: umount /mount/point. But I repeat, may I misunderstanding the process of umount, the mount I'm sure is gonna to work like I had describe.
– AtomiX84
Jan 4 at 18:44
Up to down? You mean bottom up or top down???
– FreeSoftwareServers
Jan 4 at 21:23
add a comment |
2
@PerlDuck This is also important for/etc/fstab, line order matters.
– mook765
Jan 4 at 11:37
1
Yes Absolutely, @mook765 say the true, fstab file when mount is read up to down, and when umount down to up, in other case if you try to umount /home before /home/mythtv mount will say to you the /home resource is busy, because have the /home/mythtv mounted and cannot handle it.
– AtomiX84
Jan 4 at 11:47
In which cases would/etc/fstabbe used for unmounting? The only thing I could think of isumount -a, but that command looks at what's actually mounted, not/etc/fstab.
– kasperd
Jan 4 at 16:02
by reading here seems it also used by umount: man7.org/linux/man-pages/man5/fstab.5.html, anyway after thinking a while on this (if you can confirm to me) the umount go to read the fstab when you invoke: umount /mount/point. But I repeat, may I misunderstanding the process of umount, the mount I'm sure is gonna to work like I had describe.
– AtomiX84
Jan 4 at 18:44
Up to down? You mean bottom up or top down???
– FreeSoftwareServers
Jan 4 at 21:23
2
2
@PerlDuck This is also important for
/etc/fstab, line order matters.– mook765
Jan 4 at 11:37
@PerlDuck This is also important for
/etc/fstab, line order matters.– mook765
Jan 4 at 11:37
1
1
Yes Absolutely, @mook765 say the true, fstab file when mount is read up to down, and when umount down to up, in other case if you try to umount /home before /home/mythtv mount will say to you the /home resource is busy, because have the /home/mythtv mounted and cannot handle it.
– AtomiX84
Jan 4 at 11:47
Yes Absolutely, @mook765 say the true, fstab file when mount is read up to down, and when umount down to up, in other case if you try to umount /home before /home/mythtv mount will say to you the /home resource is busy, because have the /home/mythtv mounted and cannot handle it.
– AtomiX84
Jan 4 at 11:47
In which cases would
/etc/fstab be used for unmounting? The only thing I could think of is umount -a, but that command looks at what's actually mounted, not /etc/fstab.– kasperd
Jan 4 at 16:02
In which cases would
/etc/fstab be used for unmounting? The only thing I could think of is umount -a, but that command looks at what's actually mounted, not /etc/fstab.– kasperd
Jan 4 at 16:02
by reading here seems it also used by umount: man7.org/linux/man-pages/man5/fstab.5.html, anyway after thinking a while on this (if you can confirm to me) the umount go to read the fstab when you invoke: umount /mount/point. But I repeat, may I misunderstanding the process of umount, the mount I'm sure is gonna to work like I had describe.
– AtomiX84
Jan 4 at 18:44
by reading here seems it also used by umount: man7.org/linux/man-pages/man5/fstab.5.html, anyway after thinking a while on this (if you can confirm to me) the umount go to read the fstab when you invoke: umount /mount/point. But I repeat, may I misunderstanding the process of umount, the mount I'm sure is gonna to work like I had describe.
– AtomiX84
Jan 4 at 18:44
Up to down? You mean bottom up or top down???
– FreeSoftwareServers
Jan 4 at 21:23
Up to down? You mean bottom up or top down???
– FreeSoftwareServers
Jan 4 at 21:23
add a comment |
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