If you work with storage applications or storage hardware there’s a good chance you’ve heard of ZFS. ZFS is essentially a software implementation of RAID but in my experience the most reliable it’s software RAID I’ve worked with.

Traidtion RAID instead of ZFS
Comparison to standard RAID

Over the years I’ve worked with several implementations of hardware RAID and for the most part they are pretty equal. However, most hardware RAID implementations I’ve seen — mine included — aren’t really done well. Before I move on to ZFS RAID I’m going to cover the basic problems I’ve come across with Hardware RAID setups which contributed to my switch to ZFS. In this list below RAID = “Hardware RAID”

1. RAID controllers are typically more expensive than HBAs (Host Bus Adapters)
2. Many RAID users do not properly set their cache settings on top of the fact that most cards do not come with a BBU. Lots of admins get frustrated with throughput and force write-back without a BBU
3. RAID controllers rarely keep up with drive capacity
4. Sometimes the implementation is proprietary which can make your setup less scalable (limited RAID sets, inability to mix/max nested raid or difficult to expand existing sets)
5. Most user interfaces I have worked with for hardware RAID were poor; i.e. option ROMs on the card that can’t see full disk names or OS specific utilities that are buggy or available to select OS installs only
6. I’ve yet to see a RAID card that allows you to perform a scan for errors like the ZFS scrub. I’m not saying they don’t exist, just haven’t see them