Re: Avoiding BRTFS RAID5 write hole

Hubert Tonneau
2019-11-28T10:37:45Z

Goffredo Baroncelli wrote:
>
> You are suggesting to keep the "hot" data in a RAID1 block group, and write/update the RADID5 block group only when the data is "cold" in the RAID1 cache.

Following this view, just adding a 'source data profile' (extent filter) and a 'target data profile' (overules filesystem data profile) option to 'btrfs filesystem defragment' utility would be a good starting point.
It would allow, within a RAID1 btrfs filesystem, to manualy convert some subtree to RAID5, and increase free disk space as a result, so get the best of both worlds.