hesela.devdRAID (OpenZFS)
OpenZFS dRAID is a RAID-Z variant with fixed-width redundancy groups distributed across child devices and integrated distributed-spare capacity.
OpenZFS 2.3 spreads reconstruction work across children instead of funneling writes into one spare disk. Its fixed-width layout permits sequential resilvering but pads small blocks; eight data columns with 4 KiB sectors have a 32 KiB minimum allocation. Configured distributed spares serve only their own dRAID vdev. [1]
Sequential reconstruction restores redundancy without verifying checksums and is followed by a scrub. That is a separate verification stage, not a promise of file-level access beyond parity tolerance. D-GRAID is a different research design. [2] [3]
Relations
- related
- RAIDZ, Parity declustering, Distributed spare, Resilver, D-GRAID
Limitations
- Fixed-width padding can reduce usable capacity and effective compression for small blocks. [1]
- Distributed spare capacity is a recovery resource, not extra parity. [1]
Citations
- OpenZFS 2.3 zpoolconcepts(7): dRAID virtual devices and hot spares.
- OpenZFS 2.3 zpool-replace(8): sequential reconstruction and subsequent scrub.
- Sivathanu, Prabhakaran, A. C. Arpaci-Dusseau and R. H. Arpaci-Dusseau. Improving Storage System Availability with D-GRAID. FAST 2004, sections 3, 5-7 and 9.