Re: Unable to open ctree

[Leonidas Spyropoulos <artafinde@gmail.com>]

Hi Roman,


On 03/10/16, Roman Mamedov wrote:
> On Sun, 2 Oct 2016 13:29:56 -0600
> Chris Murphy <lists@colorremedies.com> wrote:
> 
> > Well short of a bug, the problem aren't the checksums. The problem is
> > the metadata is wrong, so if you recalculate checksums you're likely
> > end up with an even more corrupted file system because it'll start out
> > trusting bad metadata.
> 
> It appears that metadata got created with profile "single", because the device
> is SSD. If this was DUP metadata, this entire problem wouldn't happen.
> It is a terrible idea to downgrade metadata to single on detecting SSDs at
> mkfs. The original rationale was that "SSDs will deduplicate it anyways", but
> there are many ways things can corrupt way before reaching the SSD (from the
> point of view of which it will look like the computer sent two different
> metadata blocks, if one got corrupted in flight), and secondly, the ability of
> SSDs to perfectly deduplicate small 4K sized pieces of data at hundreds of
> megabytes in read/write speeds is VASTLY overestimated here.

I agree that the wear in SSDs due to metadata dublications is
overestimated and since my partition appears to be screwed I will make
sure next time to force it to have another copy there.

My progress from the repairs which both failed are: https://ptpb.pw/CtbC

Next step is initialize the extent tree
btrfs check --init-extent-tree --repair /dev/sda3

Thanks,

-- 
Leonidas Spyropoulos

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