tito via Dng said on Sun, 30 Nov 2025 07:59:27 +0100

>On Sat, 29 Nov 2025 21:58:28 -0500
>Steve Litt <slitt@???> wrote:
>
>> Peter via Dng said on 29 Nov 2025 07:36:17 -0700
>>

>> >From:    Steve Litt <slitt@???>
>> >Date:    Fri, 28 Nov 2025 04:20:36 -0500  
>> >> For the same reason not to have more than one partition per disk:
>> >> It does nothing for you. If you need to grab space off other
>> >> disks for a given (former) mountpoint, a bind mount to a
>> >> directory on the othe disk does just fine.    

>> >
>> >At an abstract level, makes sense.
>> >
>> >I don't have the details. What is needed to make it work?
>> >
>> >Install packages allowing LVM?
>>
>> I wouldn't use LVM if it were the last software on earth. Ext4 or
>> btrfs etc is good enough for me.
>>
>> >Use overlayfs? An alternative to LVM?
>>
>> Never heard of it, so I can't answer.
>>
>> >What other ingredients?
>>
>> Let's say your boot drive is a single partition on an NVMe. You
>> install your OS on that, as THE single partition.
>>
>> But that's not enough disk space (let's say it's only 2TB). You also
>> have a 14TB 7200RPM spinning rust drive at /dev/sda, with a single
>> partition called /dev/sda1, and you want your /home/peter directory
>> to go there. No problem. Partition and format your spinning rust
>> drive so it has one partition, and try your best to give that
>> partition the label "bindmounts" or something else uniquely human
>> recognizable.mount that partition as /mnt/bindmounts, or, if you're
>> willing to go against the Filesystem Hierarchy Standard (FHS), just
>> /bindmounts. For the rest of this I'll assume you chose /bindmounts.
>> I'll also assume the spinning rust you just formatted is /dev/sda,
>> and the single partition containing all the drive's space is
>> /dev/sda1.
>>
>> Now back up your /home tree, hopefully somewhere off this computer.
>> Then perform the following commands:
>>
>> sudo mkdir /bindmounts
>> sudo mkdir /mnt/whatever
>> sudo mount /dev/sda1 /mnt/whatever
>> sudo mv /home /mnt/whatever/
>> sudo mkdir /home
>> sudo chmod 755 /home
>> sudo mkdir -p /home/peter
>> sudo chown peter:peter /home/peter
>> ln -s /bindmounts/home/peter /home/peter
>> ls -l /home/peter
>>
>> If the preceding command gives you the stuff you'd expect in
>> /home/peter, then so far so good. Now you need to make your home
>> directory available at boot, the earlier the better. First things
>> first, edit /etc/fstab to bind mount to /bindmounts. Add something
>> like the following to /etc/fstab, assuming your spinning rust
>> bindmounts partition has UUID 51ef83f7-c103-42cd-fbc6-90ea76019149 :
>>
>> UUID=51ef83f7-c103-42cd-fbc6-90ea76019149 /bindmounts none
>> defaults,bind,nofail 0 0
>>
>> Next, as early in the boot as possible, hopefully right after the
>> mounts in /etc/fstab are completed, put a command somewhere that
>> does:
>>
>> ln -s /bindmounts/home /home
>>
>> The preceding command precede any use of /home . If you're using
>> sysvinit look in /etc/rc.d/rc5 or whatever, and give it a number
>> that's one after the inittab mounts get mounted. If you're using
>> runit, I'd suggest right after the shellscript that brings up and
>> mounts the filesystems. On Void it's
>> /etc/runit/core-services/03-filesystems.sh, so your new file to do
>> these particular symlinks would be something like
>> /etc/runit/core-services/03-filesystems-2.sh . Obviously, back it up
>> in case a later update or new install erases your new file.
>>
>> Now, if you reboot it, everything should act as if /home/peter were
>> still on your NVMe. The real beauty is when you add a few other
>> directories, which used to be mountpoints. Instead of you having to
>> guess how much they'll hold, you can just symlink them to
>> corresponding directories under /bindmounts, and you'll have former
>> mountpoints that are now completely expandable and shrinkable. Be
>> *sure* to have all your saved email and email cache symlinked this
>> way, because those take up huge space.
>>
>> It would be nice to put /var on /bindmounts, but that might not be
>> possible, because I think it's possible that Linux starts writing its
>> logs so early that /symlinks/var has not yet been symlinked to /var .
>> And of course, you WANT your /usr/ tree on the NVMe to gain
>> spectacular performance.
>>
>> I haven't tech edited this, so you'll want to thoroughly test it out
>> on a VM guest before doing it for real. This technique is 100% Linux,
>> portable as hell, doesn't require all the layers of LVM which must be
>> unlayered to recover data, is conceptually simple, and even though it
>> sounded like a lot of instructions, it's probably doable in 20
>> minutes. You could even make a shellscript to do parts of it.
>>
>> If you do this, please let us all know how it worked out.
>>
>> SteveT
>>
>> Steve Litt
>
>Hi,
>why not simply:
>
> sudo mount /dev/sda1 /mnt
>cp -dpR /home/peter/* /mnt/
>sudo umount /mnt
>sudo mount /dev/sda1 /home/peter
>
>put something like this in /etc/fstab to have it mounted at boot
>

>UUID=xxxxxxxxxxxxxxxxxxxxxxxx  /home/peter     ext4
>defaults,comment=x-gvfs-hide        0       2

>
>If the underlying partition /home/peter is big enough (at least same
>size as /dev/sda1) you can even use it as a back up and periodically
>rsync the content of /dev/sda1 to it (obviously with umount/mount
>dance),
>
>Just my 2 cents.

If he could positively say that the only real estate on the 7200
spinning rust that he'd ever have or need would be /home/peter, your
solution would be perfect and much easier. But what if he had other
directories that he wanted to bind mount? If you start carving up the
spinning rust with different partitions, you're right back in the same
place of not having expanding directories. With the bind mount
solution, he could have all sorts of rubber-walled "mount points".

As far as why not cp -dpR, it's because I didn't know about cp -dpR
until you said it and I looked it up on the cp man page. Heck, I've
only been doing Linux for 27 years now, there's a lot I don't know. So
thanks for telling me about cp -dpR.

-d looks interesting. I'll need to try it in the near future when I
want links to come along for the ride.

SteveT

Steve Litt

http://444domains.com