dRAID

[ceinewydd]

Is HexOS thinking about supporting dRAID for larger topologies? I know the width is currently fixed, but does the team have an opinion on larger pools? When saying "larger", I'm specifically thinking of >=60 drive pools?

[Mawson]

I haven't heard of dRAID. How is it structured?

[ceinewydd]

3 minutes ago, Mawson said:

I haven't heard of dRAID. How is it structured?

https://arstechnica.com/gadgets/2021/07/a-deep-dive-into-openzfs-2-1s-new-distributed-raid-topology/

[Mawson]

OK, wow. I read just enough to get a tiny sliver of understanding and it seems super cool!

Quote

Effectively, dRAID is taking the concept of "diagonal parity" RAID one step farther. The first parity RAID topology wasn't RAID5—it was RAID3, in which parity was on a fixed drive, rather than being distributed throughout the array.

RAID5 did away with the fixed parity drive, and distributed parity throughout all of the array's disks instead—which offered significantly faster random write operations than the conceptually simpler RAID3, since it didn't bottleneck every write on a fixed parity disk.

dRAID takes this concept—distributing parity across all disks, rather than lumping it all onto one or two fixed disks—and extends it to spares. If a disk fails in a dRAID vdev, the parity and data sectors which lived on the dead disk are copied to the reserved spare sector(s) for each affected stripe.