Kernel v2.6.x started the difficult task of handling distributed database. Cron jobs got complicated and still not working. So, database such as MySql is best working with single server indexed for IP addresses. Drizzle being originally sponsored by Sun, did not get anywhere with Linux unionfs and aufs. Some where on the way to the forum, unionfs and aufs got side tracked to support Linux kernel and apps update at various repository(synaptic). Whereas distributed databases need cron jobs for data update in drams(terabyte appliance). Which needs crossbar packet switching depending on the data input location, and the rest of the distributed data storage and delivery points.

So, its still indexed servers winning the job of handling distributed database. SQL keyword search engine will get all the database regardless of locations. Cron jobs are not efficient as a basic principle of storing database in many locations. However, sooner or later cron jobs can be a savior of backup requirement. Multiple copies of database can avoid denial of service, and maintain data that will never be corrupted.

Unionfs and aufs had to have specific database hooks to do a thorough cron job with checksum, date stamped by miniature atomic clocks.