Re: Recovering MySQL Server 4 Data from crashed Harddrive

[Daniel Rindt]

Am Montag, 18. Juni 2007 12:50 schrieb Martin Friebe:
Hello Martin,
thanks for your fast informative reply. Thanks.
> there is some documentation on the File format here (MYD and MYI):
> http://forge.mysql.com/wiki/MySQL_Internals_MyISAM
>
> It may help, if you can recover the frm file
> http://forge.mysql.com/wiki/MySQL_Internals_File_Formats
>
> You 1st need to know if you look at a table with fixed or variable row
> length.
i had here a dump from the tables and her structures. so i can read in the 
dump and can mysqld recreate the frm files. then i only need the myd files 
wich contain the data, the index is in my opinion  not required instead of 
mysql really need it. (possibly that mysql can rebuild it self?)
>
> Another possibility is trying to recover the index (MYI) file, it
> contains pointers into the MYD file:
> variable length => position in pyte
> fixed length => record no (pos = record_no * record_len)
>
> It may be easier to recover the index files, because they may have a
> more recognizable structure. ( But again you need to konw the format
> (packed/unpacked, which columns) of the index, so you need the .frm file
> first.)
> The index also holds duplication of some of the data. So once you have
> the index, you can extract the data + position, and search this info on
> the remaining sectors.
i must write a tool for doing this job i guess?
The binlog is another way to recover somthing?

but what you not should forget i must first extract from a collon of data 80gb 
these files, so i first should find the files by header or footer. 

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