Terribly slow Disk Read (I/O) When fixing corrupt MyISAM table (9GB)
To anyone whom it may concern;

The problem of such slow disk read lies in the fragmentation of the data. A subsequent repair of the same table gives very high disk read i/o, indicating sequential access as opposed to random access.

The table has plenty of deleted rows, and the newly inserted records must then be read in a random fashion, resulting in slow read speeds. Again, after the table was repaired, the records where stored sequentially, and the same repair operation gave very fast results. I guess this is another reason to use InnoDB over MyISAM.

Thanks, Michael.