Re: RAID 6, 6 device array - all devices lost superblock

[Wols Lists <antlists@youngman.org.uk>]

On 28/08/2022 18:01, Peter Sanders wrote:
> It was set up on the device level, not partitions.  (I remember getting 
> some advice on the web that device was better than partition... Yay for 
> internet advice)

Well, it really SHOULDN'T matter. Except there's plenty of crap software 
that says "ooh a disk with no partition table - it must be empty - let's 
initialise it without asking the user whether it's okay". Or, as in your 
case, it seems like your mobo has wiped the start of the disk for some 
reason. We now recommend partitions, not because it's better, but as a 
defensive mechanism against the idiots out there ... :-(
> 
> I'm surveying my other disks to see what I have available to do the 
> overlay attempt.
> 
> What are the size of the overlay files going to end up being?

I'm not sure what the recommendation is, I think it used to be about 
10%, but I think you'll get away with much less. If you have the space 
ELSEWHERE eg your system partition, try and allow about 1% ie 60GB per 
drive. So you want about 360GB of free space if possible.

I don't think it's dangerous if you don't allow enough space - you'll 
just hit a "disk full" on your overlays which will be a frustration but 
not a disaster. So just give it as much room as you can afford.
> 
> I did run into UEFI vs AHCI issues early in the process.. they are all 
> set to non-UEFI.
> 
> OS update was onto a new SSD...
> 
Cheers,
Wol