Am 20.01.2017 um 02:08 schrieb Qu Wenruo:
At 01/19/2017 06:06 PM, Sebastian Gottschall wrote:
Hello
I have a question. after a power outage my system was turning into a
unrecoverable state using btrfs (kernel 4.9)
since im running --init-extent-tree now for 3 days i'm asking how long
this process normally takes and why it outputs millions of lines like
--init-extent-tree will trash *ALL* current extent tree, and *REBUILD*
them from fs-tree.
This can takes a long time depending on the size of the fs, and how
many shared extents there are (snapshots and reflinks all counts).
its about 1,8 tb. so not a great size, but millions of files. its a
build server
Such a huge operation should only be used if you're sure only extent
tree is corrupted, and other tree are all OK.
since operations like zero-log doesnt help and scrub cancles after 5
seconds with error (can't remember the exact error right now)
i'm sure there is something corrupt in it
Or you'll just totally screw your fs further, especially when
interrupted.
running since 4 days now and for sure i wont interrupt it now at this state
Backref 1562890240 root 262 owner 483059214 offset 0 num_refs 0 not
found in extent tree
Incorrect local backref count on 1562890240 root 262 owner 483059214
offset 0 found 1 wanted 0 back 0x23b0211d0
backpointer mismatch on [1562890240 4096]
This is common, since --init-extent-tree trash all extent tree, so
every tree-block/data extent will trigger such output
adding new data backref on 1562890240 root 262 owner 483059214 offset 0
found 1
Repaired extent references for 1562890240
But as you see, it repaired the extent tree by adding back
EXTENT_ITEM/METADATA_ITEM into extent tree, so far it works.
If you see such output with all the same bytenr, then things goes
really wrong and maybe a dead loop.
they are all incremental. so looks okay then. i just dont know where the
end is
Personally speaking, normal problem like failed to mount should not
need --init-extent-tree.
Especially, extent-tree corruption normally is not really related to
mount failure, but sudden remount to RO and kernel wanring.
initially i was able to mount the fs, but it turned to be ro only.
Thanks,
Qu
please avoid typical answers like "potential dangerous operation" since
all repair options are declared as potenial dangerous.
Sebastian
--
Mit freundlichen Grüssen / Regards
Sebastian Gottschall / CTO
NewMedia-NET GmbH - DD-WRT
Firmensitz: Berliner Ring 101, 64625 Bensheim
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