By some reason these files ibdata1, ib_logfile0, ib_logfile1 were been deleted from hard drive, mysql server was restarted and of course one of the database stoped with error "db.table does not exist!". Is it possible to restore somehow these files, if there are only *.frm, db.opt files?
Thanks.
Take disk image as soon as possible or mount MySQL partition read-only(if it was not on /).
Then you need to compile data recovery toolkit(install dependencies if "make" fails):
make
Then scan the disk image with page_parser. It will find InnoDB pages and sort them per page type, per index_id.
./page_parser -f /path/to/disk.img
Then you need table structures (either take them from old backup or restore from .frm). You need the structure to compile constraints_parser - a tool that fetches records from InnoDB page(s).
./constraints_parser -5f pages-XXXXXX/FIL_PAGE_INDEX/0-x/
Save output in some file. It will also generate LOAD DATA to stderr to upload the dump back to MySQL.
Check the documentation on Percona's website for more details.
From my experience, 70-80%% of data should be recoverable after this kind of accident.
Related
Yesterday, the hard drive from my dedicated server crashed. The only choice I had was to save what I could, before replacing the hard drive with a new one.
The only thing I could save was the /var/lib/mysql folder. Now I have a new hard drive with a new MySQL database running, but empty. I want to restore the data from the database I had.
I tried several things, and read over the internet that InnoDB export wasn't as easy as copying all the /var/lib/mysql folder, so I'm not sure what solution I have.
I tried to replace the new /var/lib/mysql folder with the new, but now mysqld won't run. The error log looks a lot like this, but adding innodb_force_recovery = 1 is not helping at all.
Now I'm kinda lost and out of options. Anyone faced something similar recently?
Thanks
There is a tool that can retrieve MySQL database from corrupted disk https://launchpad.net/undrop-for-innodb .
I hope you still have old hard drive attached to the server or at least an image taken from it.
Download the last revision and compile it. You'd need gcc, flex and bison as the dependency.
Let's say you have attached the old (corrupted) disk as /dev/sdb
First, you need to scan the disk and find InnoDB pages
./stream_parser -f /dev/sdb
Then you need to recover InnoDB dictionary to know table name -> index_id correspondence. See "Recover InnoDB dictionary" for details.
You would also need tables structure. Take it from some old backup. (Other options would be to recover the structure from .frm files or from InnoDB dictionary)
When you know table structure and index_id of a table you can extract the table records from InnoDB pages:
./c_parser -6f pages-actor.ibd/FIL_PAGE_INDEX/0000000000002655.page -t actor.sql
actor.sql is CREATE TABLE statement
c_parser will generate LOAD DATA INFILE command to load the dump back in MySQL.
I am attempting to restore my old databases to a new Wamp installation. However, I did not take a backup of Mysql files before I did this. Thankfully the uninstallation has not deleted all the files, but in my data folder I have :
1) All the databases (As folders)
2) auto.cnf
There are no ib* files in the old folder. Is it still possible to restore my databases somehow?
I have tried to replace the entire mysql5.6.17 folder (there has been no change of version between the installations), but Wamp remains orange and never turns green.
If I replace only the data folder, the MySQL service starts, I can see the databases, but not the tables.
If I change the path in my.ini to point to the old wamp's data folder, I cannot see the old databases at all.
EDIT : Was experimenting a bit, copying the database folders directly into the new Wamp's data folder allows me to get a list of all the tables properly, but there is no actual data in the tables, and trying to query it using MySQLWorkbench gives me the error :
Error Code: 1146. Table 'testdb.users' doesn't exist
EDIT 2 : Found this in the error log file in my data folder :
2014-08-03 06:24:46 25164 [Warning] InnoDB: Cannot open table testdb/users from the internal data dictionary of InnoDB though the .frm file for the table exists. See http://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting.html for how you can resolve the problem.
As I thought, its a problem with InnoDB's own mapping. Is there a way to resolve this manually?
If you created an INNODB database, and made no other config changes to store the actual data in seperate table spaces then all the actual data for that INNODB databases will have been stored in the \wamp\bin\mysql\mysql5.6.17\ibdata1 file.
If you do not have that file from the old install then your data is lost.
There will also be info in a \wamp\bin\mysql\mysql5.6.17\data\DATA_BASE_NAME\ folder, one .frm file for each table that was in the database, but this is basically just schema information and not actual data.
For future reference, InnoDB Backup and Recovery
GOLDEN RULE:
Always backup database (from phpmyadmin) before major changes.. better to spend 1 minute for that, than going into trouble..
How to Copy data folder
If you want to copy the database, then INSTALLATION/mysql versions should be same.. then rename newly installed data folder to i.e. data_my_old,so now there you can place the backuped data folder (it should contain ibdata1 file).
Depends on innodb_file_per_table setting.
If it was OFF then all your tables were in ibdata1. Now you have quite new ibdata1 (since you see errors "Cannot open table testdb/users from the internal data dictionary", that means InnoDB runs fresh new dictionary). That means that now the data is somewhere on the disk. The recovery is quite difficult and requires a lot of tedious work. You need to take an image of the disk, scan it with stream_parser to find InnoDB pages, then recover the InnoDB dictionary, then find index_id of every table and if the stream_parser has found this index run c_parser to extract records from the index.
If innodb_file_per_table was ON and you do see .ibd files in the databases directories then recovery is much easier. First, you may try to reconnect individual ibd files with ibdconnect or extract records from the ibd files with stream_parser/c_parser.
The mentioned tools are part of TwinDB data recovery toolkit
i have just done a google search and found this....
Go to C:\wamp\bin\mysql\mysql5.5.24\data
Find a file called "mysql-bin.index"
Rename that file to "mysql-bin.index-corrupt"
Restart the server and it will work fine, all your database will be where you left them.
I am having to restore a mysql database from .myd and .frm files. And Ii have no idea where to begin, I tried just copying them over while preserving file permisssions but to no avail what other steps do i need to take?
I have a feeling its got something to do with the ib_logfile0, ib_logfile1 and ib_data files. But dont know what to do.
You shouldn't be doing backups by dealing with the raw MySQL files. It's trivially easy to end up with a corrupted database that way. Consider what happens when you start copying the files to your backup medium - the copy will take a non-zero amount of time, during which the database could potentially write new data in various places, including the parts you've already copied. Now you're copying a modified file, a mix of old data and new data. This modified copy is almost guaranteed to be corrupted.
You should be using mysqldump or mysqlhotcopy instead, which guarantee a consistent backup.
However, on the chance that your database is relatively quiet and you managed to get a good clean backup copy, the files you need to restore depend on the type of tables you're restoring. InnoDB stores all of its data in the ib* files, regardless of database/table name. MyISAM uses files in directories named according to the database/table names.
After copying the backup copies into the correct locations, you'll have to restart MySQL, as it will still be accessing the original copies of the files.
The short question:
Is it safe skip ib_logfile* files while creating custom-made backup of MySQL installation with InnoDB engine used?
Custom-made backup is just copy all (or subset of) /var/lib/mysql + /etc/my.cnf to safe place.
As I know ib_logfile* files are recreated by MySQL on start + the files are really huge, so that may not be wise to store them in backup. And yes, assume MySQL is (correctly) stopped before backup.
It's not safe to back up a database in the manner you're describing.
The reason is that you cannot know if some data pages are still in MySQL Server's memory, pending an I/O flush to disk. So copying the files has a good chance of copying garbage, whether or not you include the ib_log files.
Don't do what you're doing. Use mysqlbackup or InnoDB's Hot Backup product.
edit:
Read Farhan Mashraqi's blog article about InnoDB Performance Optimization, in which he says you can delete the ib_log files if you have shut down MySQL Server.
InnoDB log resizing: is not as simple
as changing option and restarting. You
need to shut down MySQL server and
make sure it shuts down normally
(check error log for errors to
confirm). Then move away InnoDB log
files ib_log*. Then start the MySQL
server and check error log files to
see if it successfully created new log
files.
So yes, you should be able to do a filesystem copy of the ibdata files only. You don't need to include the ib_log files, because they should be recreated as MySQL Server starts up. I reiterate, however, that I do not recommend backing up databases with filesystem copy.
Suppose you back up a database today in this manner, using MySQL 5.0. Someday later you need to restore the backup, but by that time you'll be using some future version like MySQL 6.5 for example. Do the ib_data files still use the same internal format in that future version? Will MySQL 6.5 read those files you backed up today? You can't be sure. The backup format is intended to be more portable.
I have to restore a database that has been inadvertently DROPped in MySQL 5.0. From checking the backup files, I only seem to have .FRM files to hold the database data.
Can anyone advise whether this is all I need to perform a database restore/import from the backup, or are there other files I should have to hand to complete this?
.frm files are not the data files, they just store the "data dictionary information" (see MySQL manual). InnoDB stores its data in ib_logfile* files. That's what you need in order to do a backup/restore. For more details see here.
Restoring innodb:
(assuming your data folder is C:\ProgramData\MySQL\MySQL Server 5.5\data)
Copy the folders of the databases (named after the database name) you want to restore to C:\ProgramData\MySQL\MySQL Server 5.5\data
Copy the 3 ibdata files to the data folder ex. (C:\ProgramData\MySQL\MySQL Server 5.5\data)
_ib_logfile0
_ib_logfile1
_ibdata1
Get the size of the _ib_logfile0 in MB (it should be the same as _ib_logfile1) by File Right click -> Properties
Edit the mysql config file (mysql\bin\my.ini) for the innodb_log_file_size=343M to be exactly the ibdata files size
Run
mysqld --defaults-file=mysql\bin\my.ini --standalone --console
--innodb_force_recovery=6
Now your data should be back in your database. Export them using phpmysql or any other tool
The detailed solution you can found here:
http://www.unilogica.com/mysql-innodb-recovery/ (Article in Portuguese)
Besides the flag of innodb_force_recovery, I found another solution: innodb_file_per_table, that splits InnoDB tables in each file like MyISAM tables.
In a crash recovery you can lost less data than in single file ibdata1.