My home NAS runs mdraid RAID1 on top of two HDDs, each of which is covered by dm-integrity to guard against silent data corruption. Due to how dm-integrity lays out its data, the read-write performance is about half of what the hardware is capable of. I moved dm-integrity tags onto a separate disk to improve the situation, and bumped into a few problems along the way. More details in my blog: https://blog.tty8.org/posts/2025-04-02-moving-dm-integrity-tags-off-the-hdd-to-speed-up-raid.html

#linux #mdraid #dmintegrity

Turns out, #LVM #RAID-1 with #dmintegrity over two separate physical disks and then putting a #dmcrypt device on top of the RAID is really slow. As in, it's estimating to take a week to do the initial sync on the two 12TB WD Red drives on SATA. (For comparison, zeroing out one of these disks should take 8 hours or something.)

Apparently it's a somewhat-known problem with dm-integrity, related to its journal.

How would you build something bitrot-safe & encrypted with that hardware? #Debian 12.