Re: RAID 1 | Changing HDs

[Hannes Reinecke <hare@suse.de>]

On 9/3/25 13:55, Stefanie Leisestreichler (Febas) wrote:
> Hi.
> I have the system layout shown below.
> 
> To avoid data loss, I want to change HDs which have about 46508 hours of 
> up time.
> 
> I thought, instead of degrading, formatting, rebuilding and so on, I could
> - shutdown the computer
> - take i.e. /dev/sda and do
> - dd bs=98304 conv=sync,noerror if=/dev/sda of=/dev/sdX (X standig for 
> device name of new disk)
> 
Why would you do that?
In the end, you will have to transfer data from the entire disk
(to a new disk). And that will be the main drag, at it'll take ages.
And there it doesn't matter if you use 'dd' or md resync; both will
be taking roughly the same time.

> Is it save to do it this way, presuming the array is in AA-State?
> 
I would not recommend it.
Replacing drives is _precisely_ why RAID was created in the first place,
so really there is no difference between replacing a faulty drive or
replacing a non-faulty drive.

So I would strongly recommend to use MD tools to replace the drive;
it will serve as a nice exercise on what to do in case of a real
fault :-)

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
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