Mysql Data Migration Start error

Today after work do not know why, MySQL has been unable to start, tossing for a long time so decided to reload

My local server is Wamp, when the reload, to do data backup, I use the most simple rough backup method, is directly into the MySQL installation directory, the data can be copied one copy.

Then unload the Wamp after the reload, data migration is to put data into the same location to replace the OK

But after today's migration, MySQL can't boot, check log, show various errors

2014-11-13 13:40:29 5196 [Note] Plugin ' federated ' is disabled.
2014-11-13 13:40:29 5196 [Note] innodb:the InnoDB memory heap is disabled
2014-11-13 13:40:29 5196 [Note] innodb:mutexes and rw_locks use Windows interlocked functions
2014-11-13 13:40:29 5196 [Note] innodb:compressed tables use zlib 1.2.3
2014-11-13 13:40:29 5196 [Note] innodb:not using CPU CRC32 instructions
2014-11-13 13:40:29 16e4 InnoDB:Error:unable to create temporary file; Errno:2
2014-11-13 13:40:29 5196 [ERROR] Plugin ' InnoDB ' init function returned ERROR.
2014-11-13 13:40:29 5196 [ERROR] Plugin ' InnoDB ' registration as a STORAGE ENGINE failed.
2014-11-13 13:40:29 5196 [ERROR] unknown/unsupported storage Engine:innodb
2014-11-13 13:40:29 5196 [ERROR] Aborting

After looking at various materials, and have a rough way, delete the data directory in addition to the database folder and ibdata1 files, and then restart, OK, the small green icon came out, MySQL normal start.

* Note: Do not delete ibdata1, check the information, said this is a very important document, the preservation of INNODB related data

Of course, as a sister blogger, naturally have their own careful side, why delete the other files can be launched?

And, in the process of migration, sister paper made a variety of tests.

1. Only replace the database folder within the data, after the restart, MySQL can start, but after using Navicat to connect the database cannot open the data table, show that the data table does not exist (that is, data loss, the above ibdata1 related)

2. Replace the database folder and ibdata1 in the data directory with the backup, and restart , MySQL will not start

3. Ib_logfile0 and Ib_logfile1 deleted, restarted, MySQL started normally, connection database data table information recovery.

Roughly understand the purpose of the three parts of the document, the specific reasons, but also to dig into the future, fill the text.

Mysql Data Migration Start error