Re: How to salvage a degraded mdadm RAID1 with as little data loss as possible?

On 6/21/26 23:18, Michel Verdier wrote:
> RAID is always before LUKS : partition > RAID array > LUKS >
> filesystem


On 6/22/26 00:35, [email protected] wrote:
> "Is always" means for you "should always be" or "has to be"?
> 
> As far as I understand OP, their case is the other way around (and I
> don't see why it shouldn't be technically possible: a block device
> is a block device is a block device, after all).


On 6/22/26 01:04, Paul Leiber wrote:
> Tomas' description of my setup is correct, LUKS before RAID. It has
> been working in the past, and it is working right now again. Is this
> type of setup recommended? I don't know. BTRFS doesn't show any
> issues with this setup.


Stackable I/O layers is a feature of Linux and other operating systems. 
Depending upon which layers you want, there may be more than one way to 
stack them.


An advantage of:

     partitions > md RAID > LUKS > filesystem

Versus:

     partitions > LUKS > md RAID > filesystem

Is that the former only has to do the encryption once for the RAID 
virtual device, while the latter has to do encryption N times; once for 
each partition.


When you have a layer that combines RAID, volume management, and 
filesystems, such as ZFS and btrfs, the stackable encryption layer must 
be underneath (e.g. the latter of above two I/O layering configurations).


For N=2, magnetic hard disk drives, and a 2+ core processor with 
hardware cryptographic acceleration (e.g. Intel AES-NI), your current 
I/O layering configuration should be okay.


David