I’m planning on building a new home server and was thinking about the possibility to use disc spanning to create matching disk sizes for a RAID array. I have 2x2TB drives and 4x4TB drives.
Comparison with RAID 5
4 x 4 TB drives
- 1 RAID array
- 12 TB total
4 x 4 TB drives & 2 x 2 TB drives
- 2 RAID arrays
- 14 TB total
5 x 4* TB drives
- Several 4TB disks and 2 smaller disks spanned to produce a 4 TB block device
- 16 TB total
I’m not actually planning on actually doing this because this setup will probably have all kinds of problems, however I do wonder, what would those problems be?
I ran RAID-Z2 across 4x14TB and a (4+8)TB LVM LV for close to a year before finally swapping the (4+8)TB LV for a 5th 14TB drive for via
zpool replacewithout issue. I did, however, make sure to use RAID-Z2 rather than Z1 to account for said shenanigans out of an abundance of caution and I would highly recommend doing the same. That is to say, the extra 2x2TB would be good additional parity, but I would only consider it as additional parity, not the only parity.Based on fairly unscientific testing from before and after, it did not appear to meaningfully affect performance.