I have very bad news for you.
You should not have deleted the ibdata1 file. Here is why:
ibdata1 contains four type of information:
- table metadata
- MVCC data
- data pages (with innodb_file_per_table enabled)
- index pages (with innodb_file_per_table enabled)
Each InnoDB table created has a numercial id assigned to it via some auto increment metadata feature to each ibd file. That internal tablespace id (ITSID) is embedded in the .ibd file. That number is checked against the list of ITSIDs maintained, guess where, ... ibdata1.
I also have very good news for you along with some bad news.
It is possible to reconstruct ibdata1 to have the correct ITSIDs but it takes work to do it. While I personally have not done procedure alone, I assisted a client at my employer's web hosting to do this. We figured this out together but since the client hosed ibdata1, I let him do most of the work (30 InnoDB tables).
Anyway, here a past post I made in the DBA StackExchange. I answered another question whose root cause was the mixing up of ITSIDs.
To cut right to the chase, here is the article explaining what to do with reference to ITSID and how to massage ibdata1 into acknowledging the presence of the ITSID contained within the .ibd file.
I am sorry there is no quick-and-dirty method for recovering the .ibd file other than playing games with ITSIDs.
UPDATE 2011-10-17 06:19 EDT
Here is your original innodb configuration from your question:
innodb_file_per_table=1
innodb_flush_method=O_DIRECT
innodb_log_file_size=1G
innodb_buffer_pool_size=4G
innodb_data_file_path=ibdata1:10M:autoextend
innodb_buffer_pool_size = 384M
innodb_log_file_size=5M
innodb_lock_wait_timeout = 18000
Please notice that innodb_log_file_size is there twice. Look carefully...
innodb_file_per_table=1
innodb_flush_method=O_DIRECT
innodb_log_file_size=1G <----
innodb_buffer_pool_size=4G
innodb_data_file_path=ibdata1:10M:autoextend
innodb_buffer_pool_size = 384M
innodb_log_file_size=5M <----
innodb_lock_wait_timeout = 18000
The last setting of innodb_log_file_size takes precedence. MySQL expected to start up with the log files being 5M. Your ib_logfile0 and ib_logfile1 were 1G when you tried to start up mysqld. It saw a size conflict and took the path of least resistance, which was to disable InnoDB. That's why InnoDB was missing from show engines;
. Mystery solved !!!
UPDATE 2011-10-17 11:07 EDT
The error message was deceptive because innodb_log_file_size was smaller than the log files (ib_logfile0 and ib_logfile1), which were 1G at the time. What's interesting is this: Corruption was reported because the file was expected to be 5M and the files were bigger. If the situation were reversed and the innodb log files were smaller than the declared size in my.cnf you should get something like this in the error log:
110216 9:48:41 InnoDB: Initializing buffer pool, size = 128.0M
110216 9:48:41 InnoDB: Completed initialization of buffer pool
InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes
InnoDB: than specified in the .cnf file 0 33554432 bytes!
110216 9:48:41 [ERROR] Plugin 'InnoDB' init function returned error.
110216 9:48:41 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
In this example, the log files were already existing as 5M and the setting for innodb_log_file_size was bigger (in this case, 32M).
For this particular question, I blame MySQL (eh Oracle [still hate saying it]) for the inconsistent error message protocol.
Best Answer
I would not recommend the MEMORY storage engine
REASON #1 : No Redundancy
Whether you have a server crash or a normal system shutdown, all the data in the MEMORY table are lost. All you would have is the table structure.
REASON #2 : Mild Disk I/O
No matter what Storage Engine you choose, the
.frm
of a table is always accessed to check for table existence and availability. This will incur some disk I/O for this check.Please read past posts on the pros and cons of the MEMORY Storage Engine
May 22, 2011
: I am using the MEMORY storage engine but MySQL still writes to my disk...Why?Sep 26, 2011
: Is it feasible to have MySQL in-memory storage engine utilize 512 GB of RAM?Jan 17, 2012
: Mysql Memory table getting many locksJan 20, 2012
: How much memory will a MEMORY table take up?RECOMMENDATION
Given the two reasons for not using the MEMORY Storage Engine, I would recommend the MyISAM Storage Engine over using MEMORY or InnoDB. Why?
Looking back at Reason #1, you can have everything in RAM and have data redundancy on disk if you create the table as follows:
STEP 01) Create the table like this:
STEP 02) Create a dedicated 16MB MyISAM cache for that table:
STEP 03) Add this to /etc/my.cnf
STEP 04) Restart MySQL
That's it.
Going forward, every reload of the table will populate the dedicated key cache. Please note the
ROW_FORMAT=Fixed clause
. What that does is speed up character search 20-25% (I wrote about this before).Why not use InnoDB?
Using MyISAM, the data remains on disk but is exclusively accessed from the dedicate key cache.