partition question

partition question

[Roelof Wobben]

Hello,

I have one thing I think I don't really understand about btrfs,

Normally if I use ext4 I make a  3 partitions for my distro.

one for boot about 1G
one for home about 30G
one for root for the rest of my 100G.

Now I wonder if I want to do the same with btrfs.

Can I do the same so make 3 partitions with btrfs or can I better make 1 
partiton of 100G and make the /boot /home and  / subvolumes of the big 
partitiion.

Can one of you btfrs gurus shine a light of this matter ?

Regards,

Roelof Wobben

Re: partition question

[Chris Carlin]

On Fri, Jan 11, 2013 at 2:21 PM, Roelof Wobben <r.wobben@home.nl> wrote:
> Hello,
>
> I have one thing I think I don't really understand about btrfs,
>
> Normally if I use ext4 I make a  3 partitions for my distro.
>
> one for boot about 1G
> one for home about 30G
> one for root for the rest of my 100G.
>
> Now I wonder if I want to do the same with btrfs.
>
> Can I do the same so make 3 partitions with btrfs or can I better make 1
> partiton of 100G and make the /boot /home and  / subvolumes of the big
> partitiion.

Well. what is your motivation for doing it that way in the ext4?

If you're looking to be able to selectively mount sections of your
filesystem, then sure, subvolumes might work, but a lot of people
divide partitions this way so that they'd be independent for purposes
of reliability. Subvolumes of one btrfs partition wouldn't provide
that independence.

~Chris

Re: partition question

[Chris Murphy]

On Jan 11, 2013, at 12:21 PM, Roelof Wobben <r.wobben@home.nl> wrote:

> Hello,
> 
> I have one thing I think I don't really understand about btrfs,
> 
> Normally if I use ext4 I make a  3 partitions for my distro.
> 
> one for boot about 1G
> one for home about 30G
> one for root for the rest of my 100G.
> 
> Now I wonder if I want to do the same with btrfs.
> 
> Can I do the same so make 3 partitions with btrfs or can I better make 1 partiton of 100G and make the /boot /home and  / subvolumes of the big partitiion.
> 
> Can one of you btfrs gurus shine a light of this matter ?

You can make one Btrfs volume with /boot, /home, and / as subvolumes. GRUB2 2.00 can boot this arrangement, and that's the first caveat which is that many distributions are using older versions of GRUB2. It even works with Btrfs data/metadata profiles single, dup; and multiple device raid 0, 1, 10; and compression zlib, and lzo.

Swap still needs to be on a separate partition, as I don't think Btrfs is supporting swapfiles yet still, but maybe someone else can comment on the status of that.

While GRUB2 has LUKS support, its easier to have /boot on a separate partition for such purposes.

The limiting factor is an installer that doesn't offer the unified option, and also won't install to a pre-configured Btrfs volume.  I can vouch for Fedora 18, which can do both. That is, it will install to an existing Btrfs volume either reusing or creating subvols for home, boot, usr, var; and it will compel you to create a new subvol for root. Further, it can create new Btrfs volumes. By default with the non-custom partition path, it will put /boot on ext4. If you choose BTRFS in Installation Options > Partition scheme configuration *before* you get to custom partitioning (the screen labeled Manual Partitioning), you will be able to add a Boot mountpoint and change it from ext4 to Btrfs, and set the size however large you want. Any additional mount points other than swap will be created as subvolumes.

Chris Murphy

Re: partition question

[Hugo Mills]

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On Fri, Jan 11, 2013 at 03:34:25PM -0700, Chris Murphy wrote:
> On Jan 11, 2013, at 12:21 PM, Roelof Wobben <r.wobben@home.nl> wrote:
> > I have one thing I think I don't really understand about btrfs,
> > 
> > Normally if I use ext4 I make a  3 partitions for my distro.
> > 
> > one for boot about 1G
> > one for home about 30G
> > one for root for the rest of my 100G.
> > 
> > Now I wonder if I want to do the same with btrfs.
> > 
> > Can I do the same so make 3 partitions with btrfs or can I better make 1 partiton of 100G and make the /boot /home and  / subvolumes of the big partitiion.
> > 
> > Can one of you btfrs gurus shine a light of this matter ?

> You can make one Btrfs volume with /boot, /home, and / as
> subvolumes. GRUB2 2.00 can boot this arrangement, and that's the
> first caveat which is that many distributions are using older
> versions of GRUB2. It even works with Btrfs data/metadata profiles
> single, dup; and multiple device raid 0, 1, 10; and compression
> zlib, and lzo.
> 
> Swap still needs to be on a separate partition, as I don't think
> Btrfs is supporting swapfiles yet still, but maybe someone else can
> comment on the status of that.

   I don't know this area of the code at all well, but as I understand
it, there's been some work in the kernel (swap over NFS) which lays
down some of the underlying infrastructure we'd need to support
swapfiles on btrfs, but we don't have anything beyond that. I don't
know of anyone working on it, either.

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
  PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
       --- It's against my programming to impersonate a deity! ---       

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Re: partition question

[Roelof Wobben]

Op 11-1-2013 23:38, Hugo Mills schreef:
> On Fri, Jan 11, 2013 at 03:34:25PM -0700, Chris Murphy wrote:
>> On Jan 11, 2013, at 12:21 PM, Roelof Wobben <r.wobben@home.nl> wrote:
>>> I have one thing I think I don't really understand about btrfs,
>>>
>>> Normally if I use ext4 I make a  3 partitions for my distro.
>>>
>>> one for boot about 1G
>>> one for home about 30G
>>> one for root for the rest of my 100G.
>>>
>>> Now I wonder if I want to do the same with btrfs.
>>>
>>> Can I do the same so make 3 partitions with btrfs or can I better make 1 partiton of 100G and make the /boot /home and  / subvolumes of the big partitiion.
>>>
>>> Can one of you btfrs gurus shine a light of this matter ?
>> You can make one Btrfs volume with /boot, /home, and / as
>> subvolumes. GRUB2 2.00 can boot this arrangement, and that's the
>> first caveat which is that many distributions are using older
>> versions of GRUB2. It even works with Btrfs data/metadata profiles
>> single, dup; and multiple device raid 0, 1, 10; and compression
>> zlib, and lzo.
>>
>> Swap still needs to be on a separate partition, as I don't think
>> Btrfs is supporting swapfiles yet still, but maybe someone else can
>> comment on the status of that.
>     I don't know this area of the code at all well, but as I understand
> it, there's been some work in the kernel (swap over NFS) which lays
> down some of the underlying infrastructure we'd need to support
> swapfiles on btrfs, but we don't have anything beyond that. I don't
> know of anyone working on it, either.
>
>     Hugo.
>

Im testing Crux where I must make a custom partiion scheme before I can 
start the installer.
And Im making this scheme before because people told me that was the 
best way to work.

Roelof

Re: partition question

[dima]

>     I don't know this area of the code at all well, but as I understand
> it, there's been some work in the kernel (swap over NFS) which lays
> down some of the underlying infrastructure we'd need to support
> swapfiles on btrfs, but we don't have anything beyond that. I don't
> know of anyone working on it, either.
>
>     Hugo.
>

You can use swapfile on btrfs with mounting it via a loop device. It 
won't be incredibly fast, but it will work.

Re: partition question

[David Sterba]

On Fri, Jan 11, 2013 at 10:38:45PM +0000, Hugo Mills wrote:
> On Fri, Jan 11, 2013 at 03:34:25PM -0700, Chris Murphy wrote:
> > Swap still needs to be on a separate partition, as I don't think
> > Btrfs is supporting swapfiles yet still, but maybe someone else can
> > comment on the status of that.
> 
>    I don't know this area of the code at all well, but as I understand
> it, there's been some work in the kernel (swap over NFS) which lays
> down some of the underlying infrastructure we'd need to support
> swapfiles on btrfs, but we don't have anything beyond that. I don't
> know of anyone working on it, either.

Nobody up to my knowledge.

david