I'm not sure how exactly this happened, but I have a corrupted manifest file in
which the (partial) record just before the 983040-byte mark is filled with
zeros. The file was written to successfully after this; the entire file is
1081344 bytes long. The database worked normally for the lifetime of the
process that this happened in, but now opening it results in an error
"Corruption: missing start of fragmented record(2)".
983040 bytes is one of the points where PosixMmapFile unmaps the old region and
maps a new one, so it is possible that the fault lies in the way the data is
unmapped (and written to disk with fsync/fdatasync instead of msync).
This may be related to the bug fixed in version 1.9: Errors from Sync() are now
ignored as long as the record is readable in the file (which may be reading
from memory rather than disk). Sync failures may not be recoverable in general
(the device on which this occurred has a history of unexplained crashes and so
may just have flaky hardware), but in the event of a sync failure it may be
better to close the manifest and reopen a new file with a fresh snapshot (and
then if that cannot be done to fail the write and mark the database as
unusable).
What version of the product are you using? On what operating system?
LevelDB 1.9 on iOS 6.
Original issue reported on code.google.com by ben.darn...@gmail.com on 29 Mar 2013 at 5:41
Original issue reported on code.google.com by
ben.darn...@gmail.comon 29 Mar 2013 at 5:41