DBISAM is susceptible to corruption caused by someone (or something like a power outage) physically turning off the machine that is running the application using DBISAM. The circumstances in which this type of failure occurs and the open mode of the table(s) (exclusive or shared) will determine what type of corruption you will encounter, if any. For example, if DBISAM is in the middle of adding a record to a shared table when the power goes out, the record being added will definitely be lost. However, due to the caching involved and the fact that the buffers don't actually get flushed until after the append operation, there's a large chance that there also won't be any corruption. Corruption will likely occur if the failure occurs while the buffers are getting flushed to disk and the flush operation does not complete or only half-completes. Keep in mind that when a table is opened in exclusive mode cached data will get flushed to disk in a seemingly random manner so corruption is much more likely after a failure in such a situation. If you think you have corruption in your table(s), you should immediately verify and/or repair the table.