>Because if your drive does not support the flush track cache mechanism you are in for a world of pain. If your drive does not support CACHE_FLUSH mechanism, t

>Because if your drive does not support the flush track cache mechanism you are in for a world of pain. If your drive does not support CACHE_FLUSH mechanism, then pretty much any file system that are supposed to handle unclean shutdowns (ZFS, btrfs), etc., are going to be screwed. More generally, any time you have a file system, there will always be very delicate code. Fundamentally file systems are _hard_. It has to handle a huge amount of concurrent operations, and users want speed, so we use fine-grained locking, and there's a reason why file systems take 100 man years or so to become production ready. The btrfs folks started in 2007, and I warned them it would probably be at least 5-7 years, minimum before it would be ready for the enterprise. And now here it is five years later, and the community distributions (not the enterprise distros) are just starting to adopt btrfs. ZFS took seven years to develop before Sun announced it, and then it took a few more years before people trusted it on production servers. No one believes how hard it is when they start, but the history is pretty clear.