Re: why are / and /home the same filesystem?

2022-02-08 Thread Chris Murphy
On Tue, Feb 8, 2022 at 6:30 AM Peter Boy  wrote:
>
>
>
> > Am 08.02.2022 um 12:11 schrieb Patrick O'Callaghan :
> >
> > On Tue, 2022-02-08 at 16:48 +1030, Tim via users wrote:
> >> You may actually want hard size limits on different partitions.
> >
> > You can still have this with subvolumes. See btrfs-quota(8).
>
> Yes, a sentence beginning with „You can have this with ….“ is probably true 
> for every IT topic.
>
> The question is rather whether you can realistically have it in everyday 
> practice.

Yes, (open)SUSE enables qgroups by default for years. Fedora doesn't
enable them, but it's worth checking out 'man btrfs quota'. They're
pretty cool, and the docs consider the dilemmas raised by snapshots,
and how that affects accounting. There are some performance concerns.
Desktop users don't need to worry about it, you can enable them, play,
disable them. The whole quota btree is removed, no residue remains on
the file system.


> Workstation WG made BTRFS default with F33. Even now with F35 one year later, 
> where is easily accessible documentation for a user who wants to install 
> Workstation? Neither the current Installation Guide nor the Administrator's 
> Guide give any information about how to handle BTFRS. The complete text is up 
> to date with Fedora 25 or perhaps a bit later, only minimally updated to 
> subsequent versions.

?

https://docs.fedoraproject.org/en-US/fedora/f35/install-guide/install/Installing_Using_Anaconda/

Those are Fedora 33 screenshots. "btrfs" appears 34 times in the
document. There's an entire section on creating a btrfs layout.
https://docs.fedoraproject.org/en-US/fedora/f35/install-guide/install/Installing_Using_Anaconda/#sect-installation-gui-manual-partitioning-btrfs

Since I wrote up the lightweight changes for docs when btrfs became
the default, I'm aware that the documentation has weaknesses. It is
still LVM centric, and doesn't have hints for Btrfs nuances.

In particular, with how to get the installer to reuse the "home"
subvolume for the /home mountpoint. It is super easy to do, but
totally non-obvious. The part most folks run into is not reusing
"home" subvolume itself, which is just a matter of clicking on the
previous installation "home" and assigning it to the /home mountpoint.
But rather how to install to / because it won't let you reuse the
"root" subvolume. This is due to the installer requiring a new clean
filesystem for root. Ext4 and XFS require reformat, but Btrfs gets a
partial exemption. You don't have to reformat, but you do need a new
"root" subvolume, so you just create a new mountpoint with the +
button, specify the mountpoint as /, and leave the capacity field
blank. It'll add / mountpoint *and* create a new subvolume in the
process. You can either delete the old "root" subvolume, or keep it -
it's a matter of space available but as all subvolume share space it's
a pretty simple calculation whether you have room for it or not.


> And I see no Workstation doc listet on docs.fp.o, unlike the other Fedora 
> editions, again, after a year.

1. https://docs.fedoraproject.org/en-US/docs/
2. click on engineering teams, https://docs.fedoraproject.org/en-US/engineering/
3. click on workstation working group,
https://docs.fedoraproject.org/en-US/workstation-working-group/


> And is there an adapted installation step in Anaconda to expose an option to 
> set a max. limit (e.g. like to handle the root login - deactivated, key only, 
> . . .) and probably some other valuable capabilities? I can’t remember to 
> have seen something like that.

Workstation is a different installation experience than Server.
Workstation does a Live install, using rsync, and users are setup in
GNOME Initial Setup rather than in the installer.


> Therefore, a user is dependent on clear and informative terminology. And, 
> well, sub-„volume“ after 32 Fedora releases has a specific meaning.

There are only so many words.

I'm reminded of the word "chunk". You see this word quite a bit in
computer storage. If you specialize in one thing or another, you might
get the idea that chunk is a specialized word that has a pretty
specific meaning. And then you're surprised when you come across that
same term in another context, it means something quite different.
Chunk in mdadm is what the SNIA dictionary calls "strip" or "stripe
element" [1] On Btrfs, chunk is a different thing entirely, there's no
SNIA equivalent term. So it's certainly easy to get confused when
terms get reused.


[1] can you believe those two terms are synonyms?[2]
[2] part of the problem might be the English language, really. If
you've ever been confused about strip and stripe [3], it's not you,
it's the words themselves.
[3] These two terms are not synonyms. [4]
[4] It really could make you a bit bonkers. I've really digressed now.

-- 
Chris Murphy
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Re: why are / and /home the same filesystem?

2022-02-08 Thread Samuel Sieb

On 2022-02-08 17:28, Gordon Messmer wrote:

On 2/8/22 04:56, Peter Boy wrote:
The quote describes a situation which has gone for more of a decade 
now. Since we have LVM (when got that part of the Linux kernel? kernel 
2.6? 2004 or so? Don’t know exactly), no one would partition a hard 
disk along file system subdirectories. You create logical volumes 
instead, which can easily "changed without a reinstallation“ and space 
for any logical volume "can be expanded or restricted on the fly“. The 
latter even easier with „thin provisioning“.



Expanded, sure.  But restricted?  I don't think that's as clear for 
LVM.  IIRC, XFS can't be shrunk at all, and ext4 can only be shrunk 
offline.  Users should be able to create, destroy, or resize qgroups 
online for btrfs.


I'm unclear on what you mean is easier with thin provisioning; can you 
clarify that?


I may be naive here, as I use writable snapshots in LVM but not thin 
provisioning specifically: my impression was that users needed to be 
very careful not to allow the volume group to run out of space when 
using either of these, because filesystems generally don't deal well 
with the unexpected write failures that occur when LVM has no more 
extents to allocate.  btrfs' free space handling can be surprising to 
users, and statfs() might suggest there is more space available than 
there is, but it's not the sort of thing that can corrupt the filesystem 
itself.


Exactly!  I tried using thin provisioning once as a way to solve the 
"how much in / and how much in /home" dilemna and ended up regretting 
it.  There is no indication of how much space is really available and 
when it ran out, it was messy.  At least btrfs gives you an accurate 
number even if it might be a little confusing at first why / is getting 
so small when you fill up /home.

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Re: why are / and /home the same filesystem?

2022-02-08 Thread Gordon Messmer

On 2/8/22 04:56, Peter Boy wrote:

The quote describes a situation which has gone for more of a decade now. Since we have 
LVM (when got that part of the Linux kernel? kernel 2.6? 2004 or so? Don’t know exactly), 
no one would partition a hard disk along file system subdirectories. You create logical 
volumes instead, which can easily "changed without a reinstallation“ and space for 
any logical volume "can be expanded or restricted on the fly“. The latter even 
easier with „thin provisioning“.



Expanded, sure.  But restricted?  I don't think that's as clear for 
LVM.  IIRC, XFS can't be shrunk at all, and ext4 can only be shrunk 
offline.  Users should be able to create, destroy, or resize qgroups 
online for btrfs.


I'm unclear on what you mean is easier with thin provisioning; can you 
clarify that?


I may be naive here, as I use writable snapshots in LVM but not thin 
provisioning specifically: my impression was that users needed to be 
very careful not to allow the volume group to run out of space when 
using either of these, because filesystems generally don't deal well 
with the unexpected write failures that occur when LVM has no more 
extents to allocate.  btrfs' free space handling can be surprising to 
users, and statfs() might suggest there is more space available than 
there is, but it's not the sort of thing that can corrupt the filesystem 
itself.

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Re: why are / and /home the same filesystem?

2022-02-08 Thread Patrick O'Callaghan
On Tue, 2022-02-08 at 17:15 -0500, Robert Moskowitz wrote:
> 
> 
> On 2/8/22 12:44, Joe Zeff wrote:
> > On 2/8/22 05:56, Peter Boy wrote:
> > > no one would partition a hard disk along file system
> > > subdirectories.
> > 
> > Want to bet?  Some of us, especially home users, consider LVM a 
> > pointless complication for our use case and never use it.
> 
> I am still using EXT4 partitions (via manual partition setup) for F35
> on 
> my notebook for /boot, /, and /home:
> 
> temp stuff deleted.
> 
> $ df -h
> Filesystem  Size  Used Avail Use% Mounted on
> /dev/sda2    69G   27G   39G  42% /
> /dev/sda1   974M  293M  614M  33% /boot
> /dev/sda5   372G  241G  113G  69% /home
> 
> 
> I've still got plenty of room on my 500GB SSD drive, so I am not 
> concerned about space.  Perhaps with F36 (or F37 if I skip), I will
> try 
> and see if btrfs gains me anything for possible performance loss.
> 
> Oh, in /home/common/ietf I have ALL RFCs and drafts! (over 138K 
> drafts!), so lots of little files

I used to do the same, having to manually partition because the default
setup was LVM. However I prefer BTRFS because a) I don't have to guess
what size of partitions to create at install time, something which is
difficult to change later, and b) BTRFS includes features such as
snapshots and built-in RAID without having to deal with an additional
layer as with LVM.

Again, it's a matter of preference.

poc
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Re: why are / and /home the same filesystem?

2022-02-08 Thread Robert Moskowitz



On 2/8/22 12:44, Joe Zeff wrote:

On 2/8/22 05:56, Peter Boy wrote:

no one would partition a hard disk along file system subdirectories.


Want to bet?  Some of us, especially home users, consider LVM a 
pointless complication for our use case and never use it.


I am still using EXT4 partitions (via manual partition setup) for F35 on 
my notebook for /boot, /, and /home:


temp stuff deleted.

$ df -h
Filesystem  Size  Used Avail Use% Mounted on
/dev/sda2    69G   27G   39G  42% /
/dev/sda1   974M  293M  614M  33% /boot
/dev/sda5   372G  241G  113G  69% /home


I've still got plenty of room on my 500GB SSD drive, so I am not 
concerned about space.  Perhaps with F36 (or F37 if I skip), I will try 
and see if btrfs gains me anything for possible performance loss.


Oh, in /home/common/ietf I have ALL RFCs and drafts! (over 138K 
drafts!), so lots of little files




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Re: why are / and /home the same filesystem?

2022-02-08 Thread Joe Zeff

On 2/8/22 05:56, Peter Boy wrote:

no one would partition a hard disk along file system subdirectories.


Want to bet?  Some of us, especially home users, consider LVM a 
pointless complication for our use case and never use it.

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Re: why are / and /home the same filesystem?

2022-02-08 Thread Patrick O'Callaghan
On Tue, 2022-02-08 at 13:56 +0100, Peter Boy wrote:
> > On the other hand, the traditional approach has only a poor
> > solution to
> > restrict directories. At installation time, the harddisk can be
> > partitioned so that every directory (eg. /usr, /var/, ...) that
> > needs a
> > limit gets its own partition. The obvious problem is that those
> > limits
> > cannot be changed without a reinstallation. The btrfs subvolume
> > feature
> > builds a bridge. Subvolumes correspond in many ways to partitions,
> > as
> > every subvolume looks like its own filesystem. With subvolume
> > quota, it
> > is now possible to restrict each subvolume like a partition, but
> > keep
> > the flexibility of quota. The space for each subvolume can be
> > expanded
> > or restricted on the fly.
> 
> The quote describes a situation which has gone for more of a decade
> now. Since we have LVM (when got that part of the Linux kernel?
> kernel 2.6? 2004 or so? Don’t know exactly), no one would partition a
> hard disk along file system subdirectories. You create logical
> volumes instead, which can easily "changed without a reinstallation“
> and space for any logical volume "can be expanded
> or restricted on the fly“. The latter even easier with „thin
> provisioning“. And of course you can do backups and restores via
> snapshot, it's called LVM snapshot. What a surprise.

I've been using BTRFS for several years now and it suits me. I could
never get my head around LVM and considered it overkill for what most
workstation users need, but that's a matter of personal taste.

poc
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Re: why are / and /home the same filesystem?

2022-02-08 Thread Peter Boy


> Am 08.02.2022 um 12:11 schrieb Patrick O'Callaghan :
> 
> On Tue, 2022-02-08 at 16:48 +1030, Tim via users wrote:
>> You may actually want hard size limits on different partitions.
> 
> You can still have this with subvolumes. See btrfs-quota(8).

Yes, a sentence beginning with „You can have this with ….“ is probably true for 
every IT topic. 

The question is rather whether you can realistically have it in everyday 
practice. 

Workstation WG made BTRFS default with F33. Even now with F35 one year later, 
where is easily accessible documentation for a user who wants to install 
Workstation? Neither the current Installation Guide nor the Administrator's 
Guide give any information about how to handle BTFRS. The complete text is up 
to date with Fedora 25 or perhaps a bit later, only minimally updated to 
subsequent versions. 

And I see no Workstation doc listet on docs.fp.o, unlike the other Fedora 
editions, again, after a year.

And is there an adapted installation step in Anaconda to expose an option to 
set a max. limit (e.g. like to handle the root login - deactivated, key only, . 
. .) and probably some other valuable capabilities? I can’t remember to have 
seen something like that.

Therefore, a user is dependent on clear and informative terminology. And, well, 
sub-„volume“ after 32 Fedora releases has a specific meaning. 

(And that is one of my issues with those „missionaries“ who fight about their 
principles, but don’t care about their flock)

Peter
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Re: why are / and /home the same filesystem?

2022-02-08 Thread Peter Boy


> Am 07.02.2022 um 23:35 schrieb Patrick O'Callaghan :
> 
> On Mon, 2022-02-07 at 11:50 -0800, Gordon Messmer wrote:
>> On 2/6/22 08:17, Paolo Galtieri wrote:
>>> so why are / and /home the same device?
>> 
>> 
>> To the question of "why," I'd think the answer is in the discussion
>> held 
>> in the devel@ mailing list linked below. Generally, sharing the
>> storage 
>> pool in order to avoid running out of space in one location when
>> there 
>> was still space left in the pool due to "bad" partitioning choices
>> was 
>> seen as a benefit.
>> 
>> https://lists.fedoraproject.org/archives/list/de...@lists.fedoraproject.org/thread/IOPR2R3SCKOFUCKPLMS4MDD5664SGQFR/
> 
> From btrfs-quota(8):
> 
> On the other hand, the traditional approach has only a poor solution to
> restrict directories. At installation time, the harddisk can be
> partitioned so that every directory (eg. /usr, /var/, ...) that needs a
> limit gets its own partition. The obvious problem is that those limits
> cannot be changed without a reinstallation. The btrfs subvolume feature
> builds a bridge. Subvolumes correspond in many ways to partitions, as
> every subvolume looks like its own filesystem. With subvolume quota, it
> is now possible to restrict each subvolume like a partition, but keep
> the flexibility of quota. The space for each subvolume can be expanded
> or restricted on the fly.

The quote describes a situation which has gone for more of a decade now. Since 
we have LVM (when got that part of the Linux kernel? kernel 2.6? 2004 or so? 
Don’t know exactly), no one would partition a hard disk along file system 
subdirectories. You create logical volumes instead, which can easily "changed 
without a reinstallation“ and space for any logical volume "can be expanded
or restricted on the fly“. The latter even easier with „thin provisioning“. And 
of course you can do backups and restores via snapshot, it's called LVM 
snapshot. What a surprise.

And you can do all that without that "subvolume (only) looks like its own 
filesystem“ but in reality are not separate and independent filesystems but 
merely pretend to be.

BTRFS has specific advantages, without a doubt. And it is attractive for 
specific use cases. But it's not a silver bullet against all the tribulations 
of file storage, nor is it the only way to the future of IT. And by far it is 
not the almighty system, which fits everything as default,  as many "BTRFS 
missionaries" would have you believe, throwing buzz words around. 

Peter

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Re: why are / and /home the same filesystem?

2022-02-08 Thread Patrick O'Callaghan
On Tue, 2022-02-08 at 16:48 +1030, Tim via users wrote:
> You may actually want hard size limits on different partitions.

You can still have this with subvolumes. See btrfs-quota(8).

poc
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Re: why are / and /home the same filesystem?

2022-02-07 Thread Tim via users
On Mon, 2022-02-07 at 14:12 -0800, jdow wrote:
> Why bother with defining a separate /home at all? It gives a false
> sense of security.

There are various different reasons people do partitioning (whether
that be home, boot, var, whatever).  It's not all about security (or
lack of).

You might want it completely separate (partition or different drive
altogether) so that system updates can be done around /home without
losing it.  Of course you should have backups, but if you can keep
/home during an update, that saves having to re-import it.

A 100% filled up home doesn't wedge the system.

You may actually want hard size limits on different partitions.

You may want different mounting options.

Historically, there was also that people chose partitions for speed
optimisation (putting constantly accessed files into the fastest parts
of the drive).
 
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Re: why are / and /home the same filesystem?

2022-02-07 Thread Gordon Messmer

On 2/7/22 14:12, jdow wrote:
Ah, fix it so that when the system logs run away you can also destroy 
user data that has not been written yet. 



That's... not really how POSIX works.  And most logs on Fedora should be 
in the journal at this point, has a maximum size.



Gd planning. Why bother with defining a separate /home at all? It 
gives a false sense of security.



I don't see how there's any less "security" for /home now than there was 
before.  It's not like the old system was immune from user processes 
"running away" and filling the filesystem.  The system has never held 
space in reserve for non-root users.


There are a long list of good reasons to make /home a subvolume, 
though.  It's groundwork for system snapshots that can be rolled back in 
the event of an update failure.  It's easier to preserve /home but 
perform a clean install for everything else. Replication (possibly as a 
backup mechanism) requires subvolume as a boundary, and separating / and 
/home for that is desirable most of the time.

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Re: why are / and /home the same filesystem?

2022-02-07 Thread John Mellor


On 2022-02-07 5:39 p.m., Joe Zeff wrote:

On 2/7/22 15:12, jdow wrote:
Ah, fix it so that when the system logs run away you can also destroy 
user data that has not been written yet. Gd planning. Why bother 
with defining a separate /home at all? It gives a false sense of 
security.


Only if you define it as btrfs.


Maybe its time to ask the stupid question: Why is not /var in its own 
subvolume, and why does it not have a quota by default?  That would 
almost trivially resolve the issue of runaway logs making the system 
unusable.


--

John Mellor
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Re: why are / and /home the same filesystem?

2022-02-07 Thread Joe Zeff

On 2/7/22 15:12, jdow wrote:
Ah, fix it so that when the system logs run away you can also destroy 
user data that has not been written yet. Gd planning. Why bother 
with defining a separate /home at all? It gives a false sense of security.


Only if you define it as btrfs.
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Re: why are / and /home the same filesystem?

2022-02-07 Thread Patrick O'Callaghan
On Mon, 2022-02-07 at 11:50 -0800, Gordon Messmer wrote:
> On 2/6/22 08:17, Paolo Galtieri wrote:
> > so why are / and /home the same device?
> 
> 
> To the question of "why," I'd think the answer is in the discussion
> held 
> in the devel@ mailing list linked below. Generally, sharing the
> storage 
> pool in order to avoid running out of space in one location when
> there 
> was still space left in the pool due to "bad" partitioning choices
> was 
> seen as a benefit.
> 
> https://lists.fedoraproject.org/archives/list/de...@lists.fedoraproject.org/thread/IOPR2R3SCKOFUCKPLMS4MDD5664SGQFR/

From btrfs-quota(8):

On the other hand, the traditional approach has only a poor solution to
restrict directories. At installation time, the harddisk can be
partitioned so that every directory (eg. /usr, /var/, ...) that needs a
limit gets its own partition. The obvious problem is that those limits
cannot be changed without a reinstallation. The btrfs subvolume feature
builds a bridge. Subvolumes correspond in many ways to partitions, as
every subvolume looks like its own filesystem. With subvolume quota, it
is now possible to restrict each subvolume like a partition, but keep
the flexibility of quota. The space for each subvolume can be expanded
or restricted on the fly.

poc
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Re: why are / and /home the same filesystem?

2022-02-07 Thread jdow

On 20220207 11:50:12, Gordon Messmer wrote:

On 2/6/22 08:17, Paolo Galtieri wrote:

so why are / and /home the same device?



To the question of "why," I'd think the answer is in the discussion held in 
the devel@ mailing list linked below. Generally, sharing the storage pool in 
order to avoid running out of space in one location when there was still space 
left in the pool due to "bad" partitioning choices was seen as a benefit.


https://lists.fedoraproject.org/archives/list/de...@lists.fedoraproject.org/thread/IOPR2R3SCKOFUCKPLMS4MDD5664SGQFR/ 



Ah, fix it so that when the system logs run away you can also destroy user data 
that has not been written yet. Gd planning. Why bother with defining a 
separate /home at all? It gives a false sense of security.


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Re: why are / and /home the same filesystem?

2022-02-07 Thread Tom Horsley
On Mon, 7 Feb 2022 11:50:12 -0800
Gordon Messmer wrote:

> Generally, sharing the storage 
> pool in order to avoid running out of space in one location when there 
> was still space left in the pool due to "bad" partitioning choices was 
> seen as a benefit.

Yep, I've been partitioning systems that way for years for that very
reason. Does mean more places to look to find out why you are running
out of space, but you don't run out of space anywhere quite as fast.
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Re: why are / and /home the same filesystem?

2022-02-07 Thread Gordon Messmer

On 2/6/22 08:17, Paolo Galtieri wrote:

so why are / and /home the same device?



To the question of "why," I'd think the answer is in the discussion held 
in the devel@ mailing list linked below. Generally, sharing the storage 
pool in order to avoid running out of space in one location when there 
was still space left in the pool due to "bad" partitioning choices was 
seen as a benefit.


https://lists.fedoraproject.org/archives/list/de...@lists.fedoraproject.org/thread/IOPR2R3SCKOFUCKPLMS4MDD5664SGQFR/
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Re: why are / and /home the same filesystem?

2022-02-07 Thread Peter Boy


> Am 07.02.2022 um 10:43 schrieb GianPiero Puccioni 
> :
> 
> On 06/02/2022 23:48, Peter Boy wrote:
> about using brtfs:
> 
>> Among the cons is, as your /home grows it minimizes the space for „/„. So it 
>> can completely block your system (this could not happen with F31 and xfs.) 
>> But you can take other group activities, e.g. limit the maximum space for
>> the group /home (=subvolume /home), so that there is always enough space left
>> for /.
> 
> Another con is that it is really hard to reinstall without destroing /home.
> I'm not using brtfs again unless this is somehow corrected
> 
> GiP

Agreed. And even worse, in case of a serious filesystem issue probably not only 
data of one subvolume are lost but of allsubvolumes. Well, hopefully a most 
rare event.

Those are some cons why the server WG could not get enthusiastic about btrfs. 
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Re: why are / and /home the same filesystem?

2022-02-07 Thread Peter Boy


> Am 07.02.2022 um 00:00 schrieb Samuel Sieb :
> 
> On 2/6/22 14:48, Peter Boy wrote:
>> BTRFS subvolumes are not dedicated volumes as you may have used to in Fedora 
>> 31. That version used xfs filesystem, where every volume is a separate 
>> space, not entangeled with any other volume.
> 
> Before btrfs, workstation used ext4 as the default.  It was only server that 
> switched to xfs.

Thanks for the info. F31, "felt" it was a long time ago. 

The basic characteristics regarding the original question are the same, though. 
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Re: why are / and /home the same filesystem?

2022-02-07 Thread GianPiero Puccioni

On 06/02/2022 23:48, Peter Boy wrote:
about using brtfs:

Among the cons is, as your /home grows it minimizes the space for „/„. So it 
can completely block your system (this could not happen with F31 and xfs.) 
But you can take other group activities, e.g. limit the maximum space for

the group /home (=subvolume /home), so that there is always enough space left
for /.



Another con is that it is really hard to reinstall without destroing /home.
I'm not using brtfs again unless this is somehow corrected

GiP
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Re: why are / and /home the same filesystem?

2022-02-06 Thread Samuel Sieb

On 2/6/22 14:48, Peter Boy wrote:

BTRFS subvolumes are not dedicated volumes as you may have used to in Fedora 
31. That version used xfs filesystem, where every volume is a separate space, 
not entangeled with any other volume.


Before btrfs, workstation used ext4 as the default.  It was only server 
that switched to xfs.

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Re: why are / and /home the same filesystem?

2022-02-06 Thread Peter Boy


> Am 06.02.2022 um 18:26 schrieb Paolo Galtieri :
> 
> The system is x86_64 and I'm using brtfs.  So that clears that up:
> 
> findmnt --notruncate /
> 
> TARGET SOURCE   FSTYPE OPTIONS
> /  /dev/nvme0n1p10[/root00]
> btrfs 
> rw,relatime,seclabel,ssd,space_cache,subvolid=276,subvol=/root00
> 
> findmnt --notruncate /home
> 
> TARGET SOURCE   FSTYPE OPTIONS
> /home  /dev/nvme0n1p10[/home]
> btrfs 
> rw,relatime,seclabel,ssd,space_cache,subvolid=257,subvol=/home
> 
> However, it's still confusing to me having df show that both /home and / are 
> filled up when du -s shows that /home is only using 96G.  I found the problem 
> by doing du -s /usr/* and saw that /usr/local was consuming a lot of space.

BTRFS subvolumes are not dedicated volumes as you may have used to in Fedora 
31. That version used xfs filesystem, where every volume is a separate space, 
not entangeled with any other volume.

With version 33 Fedora workstation switched to btrfs. Here subvolumes are no 
longer dedicated separate entities, but just a kind of groups of files tagged 
the same label, „home“ or „/„. But they share the same real total disk space. 
„In real“ you have only one large partition, where you can define „tags“, 
called subvolume, which gather a bunch of files under the same label.


So, the output of df may be a bit misleading. The row „available“ refers not 
the the subvolume, but to the total space left for both of your subvolumes. 
That is a big difference to Fedora 31 you’re used to. 


There are  cons and pros, as with any technical features. One of the pros is 
you can group files without having to reserve a fixed storage area in advance. 
But still you can do "group activities“ (= subvolume operations), e.g. backup 
and restore just /home without touching system files.

Among the cons is, as your /home grows it minimizes the space for „/„. So it 
can completely block your system (this could not happen with F31 and xfs.) But 
you can take other group activities, e.g. limit the maximum space for the group 
/home (=subvolume /home), so that there is always enough space left for /. 

If you do not want this behavior, you can choose the old xfs during the 
installation, among other things. Some people use the server DVD, which 
defaults to xfs and dedicated partitions, to install the system, and add a 
graphical interface.



But nevertheless, the good news is, there is nothing wrong with your system. 

Best
Peter

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Re: why are / and /home the same filesystem?

2022-02-06 Thread Paolo Galtieri

The system is x86_64 and I'm using brtfs.  So that clears that up:

findmnt --notruncate /

TARGET SOURCE   FSTYPE OPTIONS
/  /dev/nvme0n1p10[/root00]
    btrfs 
rw,relatime,seclabel,ssd,space_cache,subvolid=276,subvol=/root00


findmnt --notruncate /home

TARGET SOURCE   FSTYPE OPTIONS
/home  /dev/nvme0n1p10[/home]
    btrfs 
rw,relatime,seclabel,ssd,space_cache,subvolid=257,subvol=/home


However, it's still confusing to me having df show that both /home and / 
are filled up when du -s shows that /home is only using 96G.  I found 
the problem by doing du -s /usr/* and saw that /usr/local was consuming 
a lot of space.


du -s /home
96971060    /home

du -s /
5436965761    /

Paolo

On 2/6/22 08:49, francis.montag...@inria.fr wrote:

Hi.

On Sun, 06 Feb 2022 11:42:22 -0500 "Garry T. Williams" wrote:


You probably have / and /home on subvolumes of a btrfs file system.

+1

The clearer way to see that is probably to use:

   findmnt --notruncate /
   findmnt --notruncate /home

Example: see the subvol= option:

findmnt --notruncate /
TARGET SOURCEFSTYPE OPTIONS
/  /dev/mapper/luks-c92191d5-7811-49f9-867c-1e300d1e9410[/root]
  btrfs  
rw,relatime,compress=lzo,ssd,space_cache,subvolid=258,subvol=/root

findmnt --notruncate /home
TARGET SOURCEFSTYPE OPTIONS
/home  /dev/mapper/luks-c92191d5-7811-49f9-867c-1e300d1e9410[/home]
  btrfs  
rw,relatime,compress=lzo,ssd,space_cache,subvolid=257,subvol=/home


That is the current default configuration now.

But it was not in F31 ...


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Re: why are / and /home the same filesystem?

2022-02-06 Thread Francis . Montagnac

Hi.

On Sun, 06 Feb 2022 11:42:22 -0500 "Garry T. Williams" wrote:

> You probably have / and /home on subvolumes of a btrfs file system.

+1

The clearer way to see that is probably to use:

  findmnt --notruncate /
  findmnt --notruncate /home

Example: see the subvol= option:

findmnt --notruncate /
TARGET SOURCEFSTYPE OPTIONS
/  /dev/mapper/luks-c92191d5-7811-49f9-867c-1e300d1e9410[/root]
 btrfs  
rw,relatime,compress=lzo,ssd,space_cache,subvolid=258,subvol=/root

findmnt --notruncate /home
TARGET SOURCEFSTYPE OPTIONS
/home  /dev/mapper/luks-c92191d5-7811-49f9-867c-1e300d1e9410[/home]
 btrfs  
rw,relatime,compress=lzo,ssd,space_cache,subvolid=257,subvol=/home

> That is the current default configuration now.

But it was not in F31 ...

-- 
francis
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Re: why are / and /home the same filesystem?

2022-02-06 Thread Garry T. Williams
On Sunday, February 6, 2022 11:17:25 AM EST Paolo Galtieri wrote:
> so why are / and /home the same device?  In the past / and /home where
> separate devices.

You probably have / and /home on subvolumes of a btrfs file system.
That is the current default configuration now.

-- 
Garry T. Williams


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Re: why are / and /home the same filesystem?

2022-02-06 Thread Peter Boy


> Am 06.02.2022 um 17:17 schrieb Paolo Galtieri :
> 
> Folks,
>   today I ran into a strange problem.  Both the root file system and the 
> /home filesystem showed 100% usage:
> 
> df -l
> Filesystem  1K-blocks  Used Available Use% Mounted on
> ...
> /dev/nvme0n1p10 283625472 281920988735540 100% /
> ...
> /dev/nvme0n1p10 283625472 281920988735540 100% /home

as you may notice / and /home use the same disk area. Are you on aarch64? And 
do you use btrfs file system (look at the output of e.g. mount)?


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