Fixing corrupted Firebird database

Question

I have a 200 GB Firebird database (created with Firebird 2.1.3, currently running 2.1.5), and it appears to be corrupted. When I try to do a backup I get:

database file appears corrupt <>
wrong page type
page 0 is wrong type (expected 0 found 1)
gds_get_segment failed

gfix ends with a

deadlock

How can I fix it?

UPDATE

While this particular database wasn't fixed, i guess the solution is try IB FirstAID.

Recommended reading:

• Common InterBase/Firebird errors caused by corruptions and their recovery chances
• Firebird and InterBase corruptions reasons

Answer 1

Here's a short step-by-step walkthrough:

• disconnect users and disable incoming connections to the database
• make a copy of database file (or two copies) and work on that
• use GFIX with -v option to validate the database file
• use GFIX with -v and -f to do full validation

If problem is not too serious, you can try to backup the broken db and restore under a new name:

• use GFIX -mend to prepare corrupt database for backup
• use GBAK -b -g to backup the database. -g disables garbage collection
• use GBAK -c to restore backup to a new database.

If you succeed, you have fixed the problem and have a functional database. If not, you can try to create an empty database with the same structure and pump the data to it .

One of the reasons why backup or restore can fail is if some broken database triggers exist, and prevent connection to the database. For example, a database trigger might use some table which has a broken index, etc. To work around this, connect to database with isql tool using -nodbtriggers option and then disable those triggers. You can enable them later when you fix other problems and get a working database again.

Another reason restore might fail is when you have broken data, so some of validity constraints (check constraints, etc.) cannot be satisfied. In this case, you can try to restore your database using -N[O_VALIDITY] command switch to gbak.

If you're interested in a more detailed information of the process of fixing the database, as well as explanation of some types of corruption, take a look at the following page:

http://www.ibphoenix.com/resources/documents/search/doc_5

If all fails, you can try IBSurgeon tool, which is able to fix most problems and extract data. Also, IBSurgeon's website has a detailed explanation of causes of database corruption and ways to fix it:

http://ib-aid.com/option,com_content/task,view/id,58/Itemid,62/

check this guide http://www.firebirdfaq.org/faq324/

Answer 2

You can open the database file with a hex editor and fix the wrong page type from 0 to 1 as explained here. It worked for me.

Multiply the wrong page's number by the page size of the database. Convert the number to hex value Open the database with a hex editor, go to offset - the number you calculated. At that position you will see the wrong number - change it to the right one, save and you are ready to backup restore.