Re: Btrfs tragedy: lack of space for metadata leads to loss of fs.

[Austin S Hemmelgarn <ahferroin7@gmail.com>]

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On 2015-08-25 10:59, Marc MERLIN wrote:
> On Tue, Aug 25, 2015 at 01:44:12PM +0000, Miguel Negrão wrote:
>> Hi list,
>>
>> This weekend had my first btrfs horror story.
>>
>> system: 3.13.0-49-lowlatency, btrfs-progs v4.1.2
>
> Sorry to say, but that's a very old kernels with many btrfs bugs, some
> did lead to corruption.
>
>> A disclaimer: I know 3.13 is very out of date, but I the requirement of
>> keeping kernel up to date clashes with my requirement of keeping a stable
>> system. At the moment I can't disturb my system as I'm doing important work,
>
> Unfortunately you have conflicting goals.
>
>> upgrading kernel requires upgrading ubuntu, which will upgrade a lot of
>> packages and might lead to problems which I don't have time to fix. One
>
> You're doing it wrong :)
> Upgrade/compile your own kernel without upgrading the OS.
>
>> block group 32...... flags 36'). This is a OCZ vertex 3, a quite fast SSD.
>
> I've had 5 (yes 5, I replaced my drive 4 times) OCZ Vertex 4 drives, and
> they all gave me corruption with btrfs on unclean power down. The last
> one didn't work any better, I just gave up and went to Samsung EVO 840
> and those have been fine.
Yeah, it's not just unclean power down that can cause this though, one 
of my friends wouldn't believe me when I told him his Vertex 3 was the 
cause of his problems till I did the following from a known good copy of 
SystemRescueCD (sda was his SSD):
dd if=/dev/urandom of=/dev/sda
dd if=/dev/zero of=/dev/sda
xxd dev/sda

and it returned thousands of blocks of non-zero data in just the first 
16G.  I wouldn't trust an OCZ drive for anything except scratch space. 
(Personally I'm a fan of Crucial SSD's due to their lower price point 
than the Samsung and Intel SSD's but almost equivalent performance and 
data integrity, but to each his own).


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