Episode: 1228
Title: HPR1228: Utilizing Maximum Space on a Cloned BTRFS Partition
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1228/hpr1228.mp3
Transcribed: 2025-10-17 21:59:15

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Howdy folks, this is 5150 for Hacker Public Radio and I'm just jumping in here real
quick for, forget everything to describe the project that has taken the last three hours
of my life.
And I'm doing this without a script so I'm just going to jump in. Here we go. I've
had an SSD sitting around for a long time to put in the computer I have in the kitchen.
And unlike most people this SSD is actually a little bigger than the spedding drive that
it's replacing since you may remember from previous podcasts. The computer I use in
the kitchen is a form of point of sale system with only an 80 gig hard drive. So I started
out this evening. Well I had some paperwork projects to do and I thought I thought to myself
well I'll get this. I'm going to find the clone that drive and then it can be running
while I'm doing this other paperwork. Well I do a lot of stuff that way. I get off on
stuff I would rather do than the stuff that I ought to be doing. I don't think I'm unique
in that respect hardly in this community. So I really can't clone the drive from the running
operating system. And I was moving that SSD. Well the first thing I did was edited my
flash-et-c-slash-f-stab to comment out the reference to the swap partition because obviously
with an SSD being a sold-state drive you can't have all those little constant reads and
writes so you don't want to have a swap partition because that's going to increase the likelihood
of drive failure. I also looked up at the same time the mounting options that would enable
trim on the device. Trim is usually able by default on Windows computers and essentially
tries to even out the wear over the entire drive. So instead of writing to the exact same
sector all the time it moves your bits and bytes around and then usually an SSD in the firmware
will have a reserved amount. Actually your SSD drive is maybe 10-20% larger than advertised. So
as memory locations fail they could actually move those sectors around. And I did find out it
seems for my group partition is XT4 and my home partition is BTRFS and the only reason I
installed butterFS in the first place is I sort of had this idea when I got the system of
eventually replacing the spinning drive with an SSD and I got on Linux questions and asked
what's the best file system for an SSD and everybody came back well the only weren't
Roy supports trim right now is butterFS so go with that. I entrust that for my group partition
so I made that the XT4. Turns out now both butterFS and XT4 can support trim and it looks like
in the boot at least the F-STAB switch that you want to put on the line for either one is
discard but I've article I found from boot I think it's a Debbie and article rather than
boot it really strongly suggested not doing that because that's going to that'll slow the drive
down if you enable trim and this is not the latest greatest fastest SSD I mean if you find
SSDs out on the market yeah you can find them right now like I did for about half the price in
dollars of the megabyte so this is a 120 gig 50 dollar drive after the rebate but the new ones
out there now for a firmware are probably a little more stable a little faster so you pay
your money and you take your chance so right now I'm going to leave trim support disabled okay so
the next step jump in there with my clone Zilla CD of course still the original hard drive still
on the box and the SSD mounted externally got nice little thing from monoprice one of those
little cradles that sits on your desk you just drop in say to drive right in there and sort of hot
I'm not sure I'd like to try that hot swapable but it's it's certainly easy enough to plug and
unplug and this is first time I've actually tried at riding to a disc mounted that way so I have
that going and I got in clone Zilla and there are options I mean there are distant image partition
image which I didn't do probably should I mean that's the back up and in image somewhere else
then you can do image onto the partition and that way you're not messing with the system with
your hard drive in there and I also didn't do what else you're supposed to do is back up the hard
drive in the first place because Roy these days the only way to back up a hard drive is to another
hard drive of the same or equal volume so I figured long as I didn't get crossed up in and
source and target I probably didn't have a very good chance of messing up the data on my original hard
drive okay so I started off and I knew I wanted to do partition to partition because if you do
disc to disc it'll do all the partitions proportional in other words so if I'm going from an 80 gig hard
drive to 120 gig hard drive it's going to just increase the size of my root partition by two
thirds and my home partition by two thirds and what my swap partition which I didn't want by two
thirds I didn't want that I wanted to create a root partition of approximately the same size
actually I should have looked at a little better for start off because my roots 12 gig I've only
got root in home and of course swap but my roots 12 gig and I'm I'm using nine of it now so I may
think better the later date of not giving myself another couple gig there and then I went from
about a 50 gig partition to the rest of the drive which is a little over 100 gig and those swap
but I found out that the volume of volume or disc to disc
selection that will format the target drive with the new partitions but partition to partition
doesn't so in other words if you're going to clone a partition to another partition you've got to
set it up that partition up first so I and still going back and operating since I don't you know I
want to be I don't want to change anything my existing operating system now that I've started messing
with it I could have done it that way instead I but and I've been hit I'll let you know I don't have
very good luck making USB boot sticks work that may be another article so I I burned a
G-Parted CD put that in there and created all my 12 my 12 gig XT for a boot partition on the
new new drive and the XT root partition the XT or so I'm sorry but butter FS home partition
for the remainder of the drive and then the rest of the drug and you know no swap so okay went back in
clones there no problem okay I'm going to do partition to partition and you know
SDA1 to SDB1 and did that and SDA2 to SDB2 and did that so of course you do it you have to go
through it twice and you know no problem and I thought I've I've had this trouble before that
it wants to clone a partition of the exact same size not so I better check it I so I booted
back into the G-Parted and you know sure enough that the root partition was close enough to the
same size that it that it worked out but the home partition you look at normally there is the
yep when you look at the partition graphically you've got the yellow part that accounts for the
use space and the white part that accounts for empty space and then I had a gray part that was
like 40% of the desk unusable space or 40% of the partition and there there's a little
explanation point on SDB2 so I click on it and it says yeah 40 gig is unutilized but you can fix it
by going into from the main G-Parted menu partition and then from the drop down menu check
not so much boys and girls because as you may know BTRFS partition still don't support FS check
okay so what do we do there is supposedly a BTRFS check command out there I think you'd install that
wasn't supported on my G-Parted CD and there's a lot of people saying that might get a little funky
out there because it's a it's a brand new command okay so this this is what you do I did try
to shrink the volume back to about the original size in G-Parted and of course you
rescan and then you then I tried to expand it and then we expanded that gray area unusable
was still there so that doesn't gonna work okay but there are bunch of BTRFS command line functions
and they were supported in the G-Parted CD I just had to do a little bit of research online to
figure out how to use them so the first thing you have to do of course to get out of the graphical
G-Parted open or terminal you have to mount the partition that you want to shrink or grow
or expand the max size because a lot of examples online what they're actually wanting to do
is going from a larger spinning drive to an SSD and they got to shrink everything down to fit
so that's the most common so it's but for the BTRFS resize command to work you have to mount the
drive at a mount point so you can't just do BTRFS resize options slash dev slash sdb2 that's
an on starter so what you do is you know most people are probably going to want to mount something
in media so you can make a directory at media even though it's on a CD but you can create that
in the file systems and you got to be root so assuming the Debian world sudo space make
your space slash media slash BTRFS that's what I called it you call it what you want okay then
you know the command is mount to the device and then space then the mount point so sudo mount
space slash dev slash sdb2 space slash media slash BTRFS okay now there's various
various arguments arguments for size in the BTRFS resize command and if it's bored you can you
can look at this just doing a man BTRFS but you can shrink your partition by a certain amount
you can expand your partition by a certain amount and it's like you know plus 2g minus 2g etc
and you can tell it just I want this big you can go sudo space BTRFS space file system base
resize space 10g space slash media slash BTRFS in my case and it it would have shrank or expanded
as necessary that partition take up exactly 10 gig what I wanted to do was expand the file system
to the maximum size of that partition so I wanted to utilize the entire partition so it's a
little bit different case but it sudo space BTRFS space file system space resize space max space slash
media slash BTRFS and then execute that and then of course you want to unmount so you you mount
space slash devs slash sdb2 or you mount the mount point you mount space slash media slash BTRFS
in my case again and then I went back in G parted boom Bob your uncle you know no no gray I just
have yellow and a whole bunch of white space so I have I haven't flopped the drives rail and tried
to boot yet but it looks like we've got the procedure for fixing the desk after doing a partition
to partition copy or clone in clone zilla and it looks like I think you'd have the same problem
if it was xt4 or whatever I mean the problem is you're you're going if you're going from a
smaller partition to a bigger partition you don't wind up with unusable space in that bigger
partition the only difference is FS check will fix it for I gather for any other file system other
in BTRFS so if you deal with BTRFS you go do a little more research and really since if I wind
up not engaging the trim then I'm not sure going with BTRFS was the best idea I haven't any trouble
with it so far but that lack of an SFS check is beginning to be troubling for me so I hope this
made sense I hope it someday helped somebody out so that they don't have to spend a lot of time
looking stuff up and in any case this has been 5150 for hacker public radio you can find my
contact information at thebigredswitch.drupleguardance.com and I'll catch you the next time
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