# Mysqld not starting due to apparent db corruption

I am very new at admining mysql, and bad for me, something caused the db to get clobbered. There are many error messages in the log that I am not sure how to safely proceed. Can you give some tips?

Here's the log:

110107 15:07:15  mysqld started
110107 15:07:15  InnoDB: Database was not shut down normally!
InnoDB: Starting crash recovery.
InnoDB: Reading tablespace information from the .ibd files...
InnoDB: Restoring possible half-written data pages from the doublewrite
InnoDB: buffer...
110107 15:07:15  InnoDB: Starting log scan based on checkpoint at
InnoDB: log sequence number 35 515914826.
InnoDB: Doing recovery: scanned up to log sequence number 35 515915839
InnoDB: 1 transaction(s) which must be rolled back or cleaned up
InnoDB: in total 1 row operations to undo
InnoDB: Trx id counter is 0 1697553664
110107 15:07:15  InnoDB: Starting an apply batch of log records to the database...
InnoDB: Progress in percents: 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73
74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
InnoDB: Apply batch completed
InnoDB: Starting rollback of uncommitted transactions
InnoDB: Rolling back trx with id 0 1697553198, 1 rows to undoInnoDB: Error: trying to
access page number 3522914176 in space 0,
InnoDB: space name ./ibdata1,
InnoDB: which is outside the tablespace bounds.
InnoDB: Byte offset 0, len 16384, i/o type 10
110107 15:07:15InnoDB: Assertion failure in thread 3086403264 in file fil0fil.c line
3922
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/mysql/en/Forcing_recovery.html
mysqld got signal 11;

This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help diagnose
the problem, but since we have already crashed, something is definitely wrong
and this may fail.

key_buffer_size=0
max_used_connections=0
max_connections=100
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections = 217599 K
bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

thd=(nil)
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
Cannot determine thread, fp=0xbffc55ac, backtrace may not be correct.
Stack range sanity check OK, backtrace follows:
0x8139eec
0x83721d5
0x833d897
0x833db71
0x832aa38
0x835f025
0x835f7a3
0x830a77e
0x8326b57
0x831c825
0x8317b8d
0x82a9e66
0x8315732
0x834fc9a
0x828d7c3
0x81c29dd
0x81b5620
0x813d9fe
0x40fdf3
0x80d5ff1
New value of fp=(nil) failed sanity check, terminating stack trace!

instructions on how to resolve the stack trace. Resolved
stack trace is much more helpful in diagnosing the problem, so please do
resolve it The manual page at http://www.mysql.com/doc/en/Crashing.html contains
information that should help you find out what is causing the crash.
110107 15:07:15  mysqld ended

-
where is the error ? –  silviud Jan 8 '11 at 16:13
Restore from your latest backup. You do keep those, right? –  jgoldschrafe Jan 8 '11 at 16:40
the error is in the mysqld log file. And yes I have backups and they are pretty good but I wanted to get the up to the minute ones. Can you tell if there is a way for a cleverer DBA than me to fix the db, or at least salvage part of it? Can you tell which db is broken? –  pitosalas Jan 8 '11 at 17:36
You should be able to restore your latest backup, and from the timestamp of that log- replay the binary log from that point up until the point it broke. This is assuming you have the binary log enabled. –  Steve Jan 10 '11 at 0:56
@silvuid here --> mysqld got signal 11; –  bahamat Jan 11 '11 at 6:18