Doesn't support transactions. The data is stored in a .MYD file and all index are stored in a .MYI file. Supports fixed record and dynamic record formats. Scanning data is fast as we can use sequential reads. Scanning on index is fast is the index doesn't contain data.
All indexes are equally fast.
Tables can be checked, repaired and optimized with the standalone tool myisamchk . Berkeley DB tables New table format in MySQL 3.23.15. Berkeley DB tables are coded and maintained by Sleepycat. Berkeley DB has been around a long time, is widely used and known to be very scalable and very robust. The data and index are stored in a .db file.