[gentoo-user] btrfs and gcc 4.9

[gentoo-user] btrfs and gcc 4.9

[James]

<snip from stefan>

I give that a try ... as I set up a fresh new btrfs-subvolume to do a
fresh new build based on my  <at> world only yesterday I will see if I can do
it with gcc 4.9 while I am at it.

Let's see if things work out and if it gets any better.
<end/snip>

Hello Stefan,

Well. OK. I'm working on a fresh install of gentoo with btrfs.
Subvolumes have me a bit mystified still. I mostly followed this
doc for a basic (raid 1) configuration with btrfs:

http://wiki.gentoo.org/wiki/Btrfs_native_system_root

If you would be so cool as to post your subvolume setup;
I'd be very grateful:

My disks look like this:

(livecd)# fdisk -l

Disk /dev/sda: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: A278FD71-0AFC-448C-817F-BAA52F97F6E1

Device           Start          End   Size Type
/dev/sda1         2048         8191     3M BIOS boot partition
/dev/sda2         8192      1024000   496M Linux filesystem
/dev/sda3      1026048   3907029134   1.8T Linux filesystem


Disk /dev/sdb: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 08A52E74-1A4D-4681-9BF6-0F3A436251E0

Device           Start          End   Size Type
/dev/sdb1         2048         8191     3M BIOS boot partition
/dev/sdb2         8192      1024000   496M Linux filesystem
/dev/sdb3      1026048   3907029134   1.8T Linux filesystem



(livecd) # gdisk /dev/sda
GPT fdisk (gdisk) version 0.8.10

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): p
Disk /dev/sda: 3907029168 sectors, 1.8 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): A278FD71-0AFC-448C-817F-BAA52F97F6E1
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 3907029134
Partitions will be aligned on 2048-sector boundaries
Total free space is 4061 sectors (2.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048            8191   3.0 MiB     EF02  grub2biosboot
   2            8192         1024000   496.0 MiB   8300  boot
   3         1026048      3907029134   1.8 TiB     8300  root


I guess what really has me "confused" is to set up a traditional
fstab, uuid, efi,  with grub2. I'm just "dense" I guess
because the aforementioned doc, I think derived from some
of "Duncan's"  postings just does not click for me.  I've botched
a few runs at btrfs (raid1) one on fresh gentoo installs, just
so you know....

Your guidance is keenly appreciated.

James

Re: [gentoo-user] btrfs and gcc 4.9

[Stefan G. Weichinger]

Am 08.11.2014 um 21:27 schrieb James:

> If you would be so cool as to post your subvolume setup;
> I'd be very grateful:

[..]

> I guess what really has me "confused" is to set up a traditional
> fstab, uuid, efi,  with grub2. I'm just "dense" I guess
> because the aforementioned doc, I think derived from some
> of "Duncan's"  postings just does not click for me.  I've botched
> a few runs at btrfs (raid1) one on fresh gentoo installs, just
> so you know....

Starting with filesystems like zfs or btrfs means learning new concepts,
yes.

You talk of subvolumes but show partitioning ... right?

OK, what do I have here?

A bit easier as I don't run rootfs on a raid on my main box. I use
btrfs-pools with redundancy as well but not in this case.

The SSD here is partitioned like this:

Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 488397168 sectors, 232.9 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 32048E18-BD83-4873-96CF-48D04B8739E6
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 488397134
Partitions will be aligned on 2048-sector boundaries
Total free space is 2349 sectors (1.1 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048          194559   94.0 MiB    EF00  ESI
   2          194560       480585727   229.1 GiB   8300  Linux filesystem
   3       480585728       488396799   3.7 GiB     8200

(partition 3 is just some slice left over afaik)

-

/dev/sda2 went into one of the btrfs "pools" here:

# btrfs fi show
Label: 'btrfs_evo'  uuid: 741835e6-95a3-49f3-ba85-2ffe3ea0730d
	Total devices 1 FS bytes used 58.28GiB
	devid    1 size 229.07GiB used 63.02GiB path /dev/sda2

-

And from here you can start to create and use btrfs-subvolumes.

I currently have the following subvolumes in this pool:

# btrfs su list /
ID 256 gen 56 top level 5 path __active
ID 257 gen 2223 top level 256 path __active/root
ID 275 gen 2224 top level 256 path __active/root_rasa
ID 281 gen 2223 top level 256 path __active/home
ID 312 gen 851 top level 256 path __active/oopsfiles

And then I use them and mount them via /etc/fstab


# grep 741835e6-95a3-49f3-ba85-2ffe3ea0730d /etc/fstab
UUID=741835e6-95a3-49f3-ba85-2ffe3ea0730d	/mnt/btrfs_pool1	btrfs
noauto,noatime,compress=lzo,subvolid=5	0	0

UUID=741835e6-95a3-49f3-ba85-2ffe3ea0730d	/	btrfs
defaults,noatime,compress=lzo,subvolid=257	0	0

UUID=741835e6-95a3-49f3-ba85-2ffe3ea0730d	/home	btrfs
defaults,noatime,compress=lzo,subvolid=281	0	0

UUID=741835e6-95a3-49f3-ba85-2ffe3ea0730d	/home/sgw/oopsfiles	btrfs
defaults,noatime,compress=lzo,subvolid=312	0	0

UUID=741835e6-95a3-49f3-ba85-2ffe3ea0730d	/mnt/root_rasa	btrfs
x-systemd.automount,noatime,compress=lzo,subvolid=275	0	0


A special note here for mountpoint /mnt/btrfs_pool1: with subvolid 5 I
get access to the "root" or top of this btrfs pool: in this mountpoint
you can access all the subvolumes like in a directory tree. I mount it
"noauto" ... I sometimes use this to modify things or work with snapshots.

-

If you set up your btrfs pool with raid1 redundancy this doesn't make
any difference from there. Create subvolumes and mount them where you
need them.

-

Does this help in any way?

Did you create your pool already?

There are lots of things to say here, please let us know where we can
help, learn and share ;-)

Stefan

Re: [gentoo-user] btrfs and gcc 4.9

[Stefan G. Weichinger]

Am 08.11.2014 um 22:07 schrieb Stefan G. Weichinger:

> Number  Start (sector)    End (sector)  Size       Code  Name
>    1            2048          194559   94.0 MiB    EF00  ESI
>    2          194560       480585727   229.1 GiB   8300  Linux filesystem
>    3       480585728       488396799   3.7 GiB     8200
> 
> (partition 3 is just some slice left over afaik)

correction: it is swap .... more than enough with 16 GB RAM ... ;-)

[gentoo-user] Re: btrfs and gcc 4.9

[James]

Stefan G. Weichinger <lists <at> xunil.at> writes:

> Does this help in any way?

Yes very much so. I use gmane to read and post,
So I have to write more than I quote.... and trim
the replied verbiage down.

> Did you create your pool already?

No. Following the gentoo wiki:

http://wiki.gentoo.org/wiki/Btrfs_native_system_root

It seems that comes after what I have done.

> There are lots of things to say here, please let us know where we can
> help, learn and share 

Yes. It's going to take me some time to test all you have written.

I'm trying to keep it as simple as possible (the old boot root swap 
type of approach for btrfs is all I'm after for now. (simple).

I have several system to experiment on, so once I get it figured out,
I'll try a more agressive set up. For now it's everything under
/root/ with subvolumes created under /root partition ?


/usr/local/  is the only thing I do special. The /home dir
is just me. So I'm trying to keep this simple and get
it working on 3 old boxes.. 

Then I'm going to put CEPH (a distributed file system)
across all three on them to run a simple Apache-mesos cluster.

https://github.com/trozamon/overlay/tree/master/sys-cluster

It's just a learning/experimenting testbed for for a (3)
node cluster, for now.

So give me a day or 2 to digest and test what you have posted.
 
> Stefan


thanks, very much,
James

Re: [gentoo-user] Re: btrfs and gcc 4.9

[Neil Bothwick]

On 8 November 2014 22:17:44 GMT+00:00, James <wireless@tampabay.rr.com> wrote:
> 
> Yes very much so. I use gmane to read and post,
> So I have to write more than I quote.... and trim
> the replied verbiage down.
> 
> node 


That's not just a gmane rule, it's good netiquette. 
-- 
Sent from my Android phone with K-9 Mail. Please excuse my brevity.

[gentoo-user] Re: btrfs and gcc 4.9

[James]

Neil Bothwick <neil <at> digimed.co.uk> writes:


> > Yes very much so. I use gmane to read and post,
> > So I have to write more than I quote.... and trim
> > the replied verbiage down.

> That's not just a gmane rule, it's good netiquette. 

Usually yes. But in this case, I would like to eventually
respond with a paragraph or 2 about everything stefan pointed
out. But, I just post to a thread(idea) one at a time,
with new information and questions.....

Gmane is too restrictive, because they save disk storage and
can carry more groups that way, according to Lars......


cheers!
James

Re: [gentoo-user] Re: btrfs and gcc 4.9

[Neil Bothwick]

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On Sun, 9 Nov 2014 02:58:48 +0000 (UTC), James wrote:

> > > Yes very much so. I use gmane to read and post,
> > > So I have to write more than I quote.... and trim
> > > the replied verbiage down.  
> 
> > That's not just a gmane rule, it's good netiquette.   
> 
> Usually yes. But in this case, I would like to eventually
> respond with a paragraph or 2 about everything stefan pointed
> out. But, I just post to a thread(idea) one at a time,
> with new information and questions.....

That's a fair point. While the 50% is a good rule of thumb, there are
times where is just doesn't make sense so you either cut too much or add
several lines of "This is to keep gmane happy" to the bottom of your post.

Or you use something other than gmane...


-- 
Neil Bothwick

Maybe... How much are you bribing me this time?

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Re: [gentoo-user] Re: btrfs and gcc 4.9

[Stefan G. Weichinger]

Am 08.11.2014 um 23:17 schrieb James:

> I'm trying to keep it as simple as possible (the old boot root swap 
> type of approach for btrfs is all I'm after for now. (simple).
> 
> I have several system to experiment on, so once I get it figured out,
> I'll try a more agressive set up. For now it's everything under
> /root/ with subvolumes created under /root partition ?
> 
> 
> /usr/local/  is the only thing I do special. The /home dir
> is just me. So I'm trying to keep this simple and get
> it working on 3 old boxes.. 

General rule(s) for subvolumes as I learned them:

* create them if you want to separate things logically

* use them if you want to use specific settings/parameters for specific
directories/subvols: for example compression, quotas ...

* use them if you want to use snapshots. A (btrfs-)snapshot is always
based on a subvolume so if you want to create snapshots for particular
areas you have to set them up as subvolumes in advance.

Splitting it into /boot, /, /home and maybe /distfiles (no compression
here ... ?) is a usual approach. Keeping it as simple as possible in the
start is a good idea. You can always add subvols later ... and move
things over ...


As I see the howto and the steps about booting:

http://wiki.gentoo.org/wiki/Btrfs_native_system_root#Embedding_an_initram_filesystem

I didn't do it that way but used dracut for the initrd ... the
ml-archives have some threads around learning this (combined with
systemd and LVM stuff back then I spent quite some time ...).

Canek's tool kerninst also helps here:

https://github.com/canek-pelaez/kerninst

[gentoo-user] Re: btrfs and gcc 4.9

[James]

Stefan G. Weichinger <lists <at> xunil.at> writes:


> General rule(s) for subvolumes as I learned them:

> * create them if you want to separate things logically

> * use them if you want to use specific settings/parameters for specific
> directories/subvols: for example compression, quotas ...

> * use them if you want to use snapshots. A (btrfs-)snapshot is always
> based on a subvolume so if you want to create snapshots for particular
> areas you have to set them up as subvolumes in advance.

> Splitting it into /boot, /, /home and maybe /distfiles (no compression
> here ... ?) is a usual approach. Keeping it as simple as possible in the
> start is a good idea. You can always add subvols later ... and move
> things over ...

Yea, I'm still planning what exactly I'm going to do
what needs to be snapshots and where I'll store and work
on various codes

> As I see the howto and the steps about booting:

>
http://wiki.gentoo.org/wiki/Btrfs_native_system_root#Embedding_an_initram_filesystem

> I didn't do it that way but used dracut for the initrd ... the
> ml-archives have some threads around learning this (combined with
> systemd and LVM stuff back then I spent quite some time ...).

> Canek's tool kerninst also helps here:

> https://github.com/canek-pelaez/kerninst


I'm also trying to work out the booting setup, maintenance and 
recovery in the event of failures.

I'll post what I come up with for you and other to comment
on and make suggestions for improvment.

Thanks,
James

Re: [gentoo-user] Re: btrfs and gcc 4.9

[Stefan G. Weichinger]

Back to the topic of the thread:

As I mentioned I started to prepare a new root-filesystem within a
btrfs-subvolume.

By using systemd-nspawn I "chroot" into it and can rebuild my system
from scratch while running my main installation.

I set up a second grub2-entry as well so I can even chose booting this
and that root-partition (or better: "root-subvolume" )

I try to build the new system with gcc-4.9, just being curious, 4.9.2
for now.

emerge -e @system went through fine completely ... but my @world is a
different thing. Some gnome-related stuff does not compile yet,
additionally complicated by the fact that I run the very unstable
packages from the gnome-overlay, bringing gnome 3.14. This runs fine on
my main installation (and on a thinkpad as well, btw). But gcc-4.9 might
be a bit too early ;-)

Anyway.

This is just a small project for playing around ...

Stefan

Re: [gentoo-user] Re: btrfs and gcc 4.9

[Stefan G. Weichinger]

Am 13.11.2014 um 19:12 schrieb Stefan G. Weichinger:

> emerge -e @system went through fine completely ... but my @world is a
> different thing. Some gnome-related stuff does not compile yet,
> additionally complicated by the fact that I run the very unstable
> packages from the gnome-overlay, bringing gnome 3.14. This runs fine on
> my main installation (and on a thinkpad as well, btw). But gcc-4.9 might
> be a bit too early ;-)

Up and running with gnome 3.14 as well.
Snappy performance so far.
Only a few packages left to care about.

Nice.

Re: [gentoo-user] Re: btrfs and gcc 4.9

[Stefan G. Weichinger]

Am 13.11.2014 um 21:34 schrieb Stefan G. Weichinger:

> Up and running with gnome 3.14 as well.
> Snappy performance so far.
> Only a few packages left to care about.
> 
> Nice.

Just another status for the records:

so far I am running happily on ~amd64 built from scratch with
sys-devel/gcc(**)4.9.2

-

As mentioned before I set up a separate btrfs-subvolume and started a
fresh installation there ... instead of good old chroot I used
systemd-nspawn and built up a fresh new system inside there, based on my
@world (and feeding it configs from /etc here and then).

-

There were some packages (<3) on the way that gave me issues which I did
NOT document fully ... ;-)  Some grep-wizardry might bring them up, yes.

For now things are running fine, even with gnome-3.14 from the
gnome-overlay.

-

It would be fun maybe to boot into the old btrfs-subvolume now and
switch back to my system as it was some weeks ago ...

Stefan