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Siduction Forum => Software - Support => Topic started by: Lanzi on 2014/03/28, 13:48:45

Title: Why is my btrfs disk not mounting?
Post by: Lanzi on 2014/03/28, 13:48:45
I took the parameters from an ubuntu pgae, but my drive is not mounted autimatically.
If I do it manually it is mounting!

fstab
Quote
UUID=4cb0f615-664f-4911-a0a8-3800dddexxxx    /home/h/disk3        btrfs        defaults,subvol=@    0   1


blkid
Quote
/dev/sda1: LABEL="disk3" UUID="11cdeb6d-81c1-4767-ae6f-1d26881cxxxx" UUID_SUB="4cb0f615-664f-4911-a0a8-3800dddexxxx" TYPE="btrfs"
Title: Re: Why is my btrfs disk not mounting?
Post by: dibl on 2014/03/28, 14:03:22
Hi Lanzi.  Is that an entire hdd, or only a partition?  I have a 2-drive btrfs filesystem, here is the /etc/fstab line to automatically mount it:

Code Select
UUID=9025bea6-b615-470a-8759-df1b13f63b52     /mnt/DATA            btrfs        device=/dev/sdd,device=/dev/sde,compress=lzo,space_cache,inode_cache   0    0




I wonder if the UUID in /etc/fstab should be the first UUID in your blkid output?
Title: Re: Why is my btrfs disk not mounting?
Post by: Lanzi on 2014/03/28, 14:46:26
an entire disk!
Title: Re: Why is my btrfs disk not mounting?
Post by: dibl on 2014/03/28, 15:33:59
Try using the first UUID in the /etc/fstab mount line -- the one that goes "11cdeb6d-81c1-4767-ae6f-1d26881cxxxx"
Title: Re: Why is my btrfs disk not mounting?
Post by: Lanzi on 2014/03/28, 16:14:02
Ah, sorry, now I see.
I copied the wrong line.
I already tested boths uuids with fstab and unfortunatly I copied only the second.

I tested both UUID, also the frist and the result is the same -> no automount!

SO, I suppose its a problem with the options.


Title: Re: Why is my btrfs disk not mounting?
Post by: dibl on 2014/03/28, 17:46:04
I'm not sure -- your setup looks like others used in examples that I can find around the web.  But clearly you need to mount the btrfs "root" -- the main filesystem itself, which is defined by the first UUID that you have.  I have not made use of subvolumes -- that must be where the trouble is.
Title: Re: Why is my btrfs disk not mounting?
Post by: timc on 2014/03/28, 20:13:21
Well, if his btrfs is defined on an entire disk, then his root is a subvolume. I don't do that (whole disk), but I do have several subvolumes mounted at bootup. I do not think that, in and of itself, is a problem.

Tim
Title: Re: Why is my btrfs disk not mounting?
Post by: Lanzi on 2014/04/03, 18:47:41
Hi guys,
sorry for the delay. had a lot to do this week.

I changed my parameters in fstab to dibls:

compress=lzo,space_cache,inode_cache
and now it works.

I really don't understand what was wrong with the old ones.

So, thanks a lot to everybody involved!


One more question: dibl: what defines your parameter
"device=/dev/sdd,device=/dev/sde"  ?


Title: Re: Why is my btrfs disk not mounting?
Post by: dibl on 2014/04/04, 13:48:54
Quote from: Lanzi on 2014/04/03, 18:47:41
One more question: dibl: what defines your parameter
"device=/dev/sdd,device=/dev/sde"  ?


When you make a single BTRFS filesystem on multiple disks (https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices), that is how you mount it -- you have to use the device IDs in the mount line in /etc/fstab.
Title: Re: Why is my btrfs disk not mounting?
Post by: Lanzi on 2014/04/04, 17:51:33
ah, okay...
I will read about it. Sounds interesting to determine device to discs!
Title: Re: Why is my btrfs disk not mounting?
Post by: dibl on 2014/04/04, 19:01:27
I like the added security of striped data (RAID 0) and mirrored metadata (RAID 1) on a pair of drives.  I do back up my data regularly, but theoretically I can recover from a single drive failure without needing to restore a backup.   (But I hope I never have to test the theory!)
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