There is an interesting thread over on the AVS forums discussing the pros and cons of unRAID, FlexRAID and SnapRAID. They all have their advantages and disadvantages, and the following post bullet points them nicely.
- unRAID and FlexRAID offer real-time parity
- both only offer a single parity drive solution at this stage (both have plans for dual parity setups in real-time but who gets there first is anyone’s guess)
- FlexRAID real-time is not as stable as unRAID for realtime parity (it does not handle anything that does not pre-allocate, and it hates Teracopy – author is aware of this issue)
- Only unRAID offers simulated drive failures — all other solutions won’t offer up your lost files until you do a full repair
- FlexRAID and unRAID again both offer this functionality (optional in flexraid, but mandatory for realtime raid)
- unRAID allows you to both view and operate on the individual drives that comprise the array without impacting realtime parity. Others only allow this functionality in Snapshot mode.
- FlexRAID and unRAID handle sharing via their interfaces
- SnapRAID etc. does sharing via the underlying OS
- FlexRAID is the fastest for realtime
- unRAID can incorporate a cache drive
- I’m not sure of what the speed is like comparing snapshot parity between FlexRAID and SnapRAID (but am perfectly fine with the performance of SnapRAID)
- unRAID wins this by a country mile, the community is the most active and very helpful
- SnapRAID and FlexRAID are also helpful, but suffer from lack of community participation
- FlexRAID has no limit on how many parity drives you can employ
- SnapRAID is limited to 2, but have plans for 3 drives in the future (probably distant future)
- unRAID does not have this feature
- SnapRAID does checks on the block level
- FlexRAID does checks on the file level
Thanks to hdkhang for summarising.