[xubuntu-users] How to get Btrfs on 2nd partition of USB HDD to automount as read/write

dg1727 dg1727 at hushmail.com
Sun Aug 19 19:44:37 UTC 2012

On Fri, 17 Aug 2012 15:07:06 -0400 dg1727 <dg1727 at hushmail.com> 
>The following is based on 
>I have a user with an Xubuntu 12.04.1 laptop, 32-bit.  He needs to 
>use a USB hard disk drive which has 2 partitions:  the 1st 
>partition is NTFS and the 2nd partition is Btrfs.  
>When he plugs in the hard drive, both partitions auto-mount OK, 
>except that the Btrfs partition automounts read-only.  That is, 
>the permissions of the directories in /dev are drwx------ for the 
>NTFS and dr-xr-xr-x for the Btrfs.  
>How can the OS be set up so that the Btrfs will automount 
>The "dmesg" command shows the following on plug-in of the drive:  
>[ 7253.520087] usb 2-4: new high-speed USB device number 11 using 
>[ 7253.656344] scsi11 : usb-storage 2-4:1.0
>[ 7256.651677] scsi 11:0:0:0: Direct-Access     TOSHIBA  External 
>USB 3.0 0001 PQ: 0 ANSI: 6
>[ 7256.654722] sd 11:0:0:0: Attached scsi generic sg2 type 0
>[ 7256.656970] sd 11:0:0:0: [sdb] 1465149168 512-byte logical 
>blocks: (750 GB/698 GiB)
>[ 7256.660515] sd 11:0:0:0: [sdb] Write Protect is off
>[ 7256.660534] sd 11:0:0:0: [sdb] Mode Sense: 1f 00 00 08
>[ 7256.662509] sd 11:0:0:0: [sdb] No Caching mode page present
>[ 7256.662523] sd 11:0:0:0: [sdb] Assuming drive cache: write 
>[ 7256.668478] sd 11:0:0:0: [sdb] No Caching mode page present
>[ 7256.668498] sd 11:0:0:0: [sdb] Assuming drive cache: write 
>[ 7256.673838]  sdb: sdb1 sdb2
>[ 7256.681474] sd 11:0:0:0: [sdb] No Caching mode page present
>[ 7256.681493] sd 11:0:0:0: [sdb] Assuming drive cache: write 
>[ 7256.681507] sd 11:0:0:0: [sdb] Attached SCSI disk
>[ 7257.545702] device label partition_label devid 1 transid 19 
>[ 7257.546790] btrfs: disk space caching is enabled
>Neither the "usbmount" nor "pmount" packages are installed, but 
>"thunar-volman" is installed.  I did install "pmount" only to find 
>that it appears to be meant to be invoked manually, so I un-
>installed it again.  
>"uname -rv" reports:  
> 3.2.0-29-generic #46-Ubuntu SMP Fri Jul 27 17:04:05 UTC 2012
>The "groups" command shows that the user is a member of the 
>following (in addition to a group named after his username):  
> adm dialout fax cdrom floppy tape sudo dip video plugdev fuse 
>lpadmin sambashare
>The "mount" command shows for the Btrfs partition in question:  
> /dev/sdb2 on /media/[partition_label] type btrfs 
>(I have substituted [partition_label] for the partition label, 
>which is all letters, no punctuation marks.)
>Because "mount" shows "rw", does that mean that it is the 
>configuration of Btrfs, not the configuration of automounting, 
>that is at issue?  
>I appreciate any help.  

Thanks in advance for any useful comments about this issue.  

Sorry that this follow-up message won't show up under the same 
thread as the original message, but I think that any future follow-
ups by me to this list (even for different issues) will be 
correctly under the original thread.  (On the list options page, I 
have turned on "Receive your own posts to the list?" and intend to 
reply to those in future so the threading will work right.)  


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