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

David Christensen <[email protected]>
Newsgroups gmane.linux.debian.user
Message-ID <[email protected]>
On 6/23/26 01:22, [email protected] wrote:
> On Tue, Jun 23, 2026 at 08:00:11AM +0200, Michel Verdier wrote:
>> On 2026-06-22, [email protected] wrote:
>>> On 6/21/26 23:18, Michel Verdier wrote:
>>>> RAID is always before LUKS : partition > RAID array > LUKS > filesystem
>>>
>>> "Is always" means for you "should always be" or "has to be"?
>>
>> "has to be". LUKS encrypt a partition in a unique way. So 2 encrypted
>> partitions are always different and cannot be synced.
> 
> I think that is wrong.


+1


Both configurations work, but have different performance and security 
considerations:

* partitions > RAID > encryption > filesystem

     Will encrypt the RAID virtual block device, saving CPU cycles and 
requiring one passphrase and/or key.

* partitions > encryption > RAID > filesystem

     Will encrypt each partition, arguably improving security but 
requiring more CPU cycles and passphrases/ keys.


My SOHO file server uses ZFS, which combines RAID > filesystem.  (ZFS 
native encryption has issues, so I avoid it.)  So, the file server must 
use a variation of the above latter I/O layering configuration:

     partitions > encryption > ZFS


David
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