I’m very mutch not an expert on BTRFS, SnapRAID and NAS’ but here’s how I see it working:
You currently have four drives: 2 x 1TB, 1x 2TB, 1 x 3TB
You format the individual drives with BTFS. With SnapRAID
you set the 3TB drive to act as parity for the 2 x 1TB and 1x 2TB. You then use
BTRFS to pool space of the 2 x 1TB, 1x 2TB into a 4TB pool.
Later you get another 2TB drive. If you server has capacity
for more drives, add it to the pool and have 6TB available. If you can’t fit
more drives swap out one of the 1TB’s and have 5TBs.
Why do you hate unRAID so much?
Unintuitive, unstable (for me at least) GUI with missing features that needs user made plugins and command line intervention to be functional.
Resource intensive (just formatting drives near maxes out my CPU)
Slow network file transfer speed. They recommend adding cache drive but that takes a slot form you license and even with cache drive is still slow.
I have not used SnapRAID before, but from what you wrote, it seems like there’s more control available wrt parity. I am curious to learn about the benefits in more detail. Could you please explain?
As I understand it parity operations in SnapRAID aren’t real-time but on a user defined schedule.
SnapRAID allows for as many parity drives as you want, I think BTRFS is limited 2.
BTRFS and hence Rockstor allows usage of different size drives. How is it different in SnapRAID?
As I understand it BTRFS will treat all drive as if their capacity were that of the smallest drive. SnapRAID would give you the combined capacity excluding parity drive.
On your other proposed gains, could you elaborate how you see them being useful at a higher level?
A raid option that allows for different size drives with parity (not JBOD)
Lower entry cost
Flexible expansion options
Data accessible on drives removed from array
Emergency data access in the event of server failure
Ability to control when parity happens
Parity operations are not free, schedule sync operation for when you can afford the CPU time cost.
Would eliminate write amplification that occur in RAID5 and RAID6 arrays.
Allow for the reset of data to the state of when the last sync job was run.
Only spin up drives being used
Reduced power consumption
Extended drive live