Mounting newer BtrFs version in CentOS 6.6

wagscat123 · 01-20-2015, 04:21 PM

Hi all,

I have a CentOS 6.6 installation that took the place of an openSUSE 13.1 installation. I need to use the older CentOS, but would like to be able to mount my BtrFS home partition. When I try to mount it, I get the following error:

Code:

[root@localhost /]# mount /dev/sda6 /a
mount: wrong fs type, bad option, bad superblock on /dev/sda6,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

I assume it is because openSUSE 13.1 used a newer BtrFS with unsupported features in the older CentOS 6. Are there ways to disable the newer BtrFS features in an openSUSE live CD, or to update the BtrFS driver and progs in my CentOS 6.6?

John VV · 01-21-2015, 01:31 PM

CentOS 7.0 should support that file system

remember that cent6 features and major versions of software were LOCKED with rhel 6.0 November of 2010

wagscat123 · 01-21-2015, 04:16 PM

I'm using 6 so I can remain in sync with the platform that my CompSci instructors will be using. Know any BtrFS workarounds? One thing I thought of is indiviually upgrading the kernel and checking for updates. CentOS 6's wiki says it supports BtrFS with btrfs-progs installed, and it still didn't mount my homr partition after that, which lead me to think it has something to do with more recent features in BtrFS

John VV · 01-21-2015, 09:54 PM

you will likely have issues if the /home and / partitions are btrfs

try disabling SELinux ( setenforce=0)
then see

the operating system checks the SE context and if wrong ( or missing ) will refuse to mount or boot or log in that user

are you trying to REUSE the opensuse /home/username partition on cent6

if so that will NOT work

for starters the uuid on suse starts at 1000 for root and 1001 for the first normal user
cent uses 500 and 501

next
opensuse dose NOT use SELinux ( it can but a custom built kernel)

se on Cent WILL preven mounting of /home if the se context and user permission are off

and they will be

wagscat123 · 01-22-2015, 11:45 AM

I tried disabling SELinux and mounting that partition, and I still received the same error message. I'm also testing to see if it mounts before making it my new home partition by mounting it to another non-system directory until I have it mounting in the mean time.

Would upgrading just the kernel or disabling new BtrFS features still be a viable approach?

John VV · 01-22-2015, 12:02 PM

updating the kernel to a non standard cent6.6 kernel
will not help if you are trying to reuse the opensuse /home partition and the opensuse /home/"UserName" folder on cent 6

reusing /home between OS's almost NEVER works

copy off the data that is needed
pictures
music
documents
and so on

and use the CENTOS 6 created "/" "/home" ext4 ( or the default LVM )

Quote:

and it still didn't mount my homr partition after that,

if you are NOT reusing the opensuse /home partition
but just need to mount it and copy data off it

please post the full command you are using
it should be something like this

Code:

su -
mkdir /mnt/BtrfsHome
mount -t btrfs /dev/sd?? /mnt/BtrfsHome

or
are you trying to use " fstab "
-- from RHEL 7 documentation

Code:

--- over many devices ----
/dev/sdb    /mnt    btrfs    device=/dev/sdb,device=/dev/sdc,device=/device/sdd,device=/dev/sde    0

on the redhat family of OS's you need to mount a partition in a folder on /
such as
/mnt/folder
/DATA/folder
/opt/folder
-- DO NOT use "/media" that is for the AUTO mounted devices

wagscat123 · 01-22-2015, 01:03 PM

Here's the exact command I used and its error message:

Code:

[root@localhost ~]# mount -t btrfs /dev/sda6 /nh
mount: wrong fs type, bad option, bad superblock on /dev/sda6,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

At this point I just want to get it mounted, copy my data, then re-format the partition.

John VV · 01-22-2015, 01:11 PM

mounting a partition directly on / ( "/nh" ) will cause problems
se will NOT want to allow you to do it ( big major security problem that it will try to STOP you from doing)

was that opensuse made btrfs partition spread over MANY devices ( a lvm or raid?) suse defaults to a LVM install

what is the output from the "help" the error offered
" dmesg | tail "

now you do need to run it RIGHT AFTER the error is given

wagscat123 · 01-22-2015, 01:28 PM

I tried mounting it into /mnt/nh and I still got the same error.

From dmesg_| tail:

Code:

[root@localhost /]# dmesg | tail
usb 3-1: configuration #1 chosen from 2 choices
gvfs-gphoto2-vo[7307]: segfault at 3 ip 00007f40dcff1290 sp 00007fff8181d470 error 4 in ptp2.so[7f40dcfd1000+4f000]
device fsid 1000ecb1-1faa-4680-8cb0-31f72cdba181 devid 1 transid 36266 /dev/sda6
btrfs: disk space caching is enabled
BTRFS: couldn't mount because of unsupported optional features (40).
btrfs: open_ctree failed
device fsid 1000ecb1-1faa-4680-8cb0-31f72cdba181 devid 1 transid 36266 /dev/sda6
btrfs: disk space caching is enabled
BTRFS: couldn't mount because of unsupported optional features (40).
btrfs: open_ctree failed
[root@localhost /]#

I didn't spread the BtrFS filesystem over many partitions - it is just on a logical partition on a ms_dos partition table

John VV · 01-22-2015, 04:56 PM

this basically says it all

Quote:

BTRFS: couldn't mount because of unsupported optional features (40).

remember rhel/cent 6 was LOCKED in 2010

all major( minor upgrades and improvments YES but not major ones) features and software was locked back then

opensuse 13.1 however is WAY newer using newer options that what was around 5 years ago .

https://access.redhat.com/documentat.../ch-btrfs.html

to quote the rhel guide

Quote:

Btrfs is not a production quality file system at this point. With Red Hat Enterprise Linux 6 it is at a technology preview stage and as such is only being built for Intel 64 and AMD64.

also redhat only added btrfs as a "PREVIEW "
--- pdf file-6.6_Technical_Notes
https://access.redhat.com/documentat...otes-en-US.pdf
"Red Hat Enterprise Linux 6 includes Btrfs as a technology preview "

wagscat123 · 01-23-2015, 01:50 PM

In that case, I'll just mount it with the openSUSE 13.1 Live CD and backup my data then make a new ext4 partition in its place.
Thanks

wagscat123 · 01-23-2015, 02:20 PM

John_VV - I once noticed you answered a question I had on QGIS. Do you work in a field related to geology of some sort?