recovering RAID5 with mdadm command : dik busy??
 

Due to a failure of the hardware of NAS Lacie 5big, I want to trasnfert the data to a new Synology NAS ;
the only way I know to do it is to mount each HDD in order to copy after the data.
fdisk provides me the list of device (sdc1-10)in this HDD so I have tried the mdadm -A command to prepare the md0 device BUT I got always sdc2 (the biggest partition) busy!
but this partiion is not used elsewhere.
the force option in the mdadm does nothing.

any clue to solve my problem ?

Ps : my system is OPENSUSE LEAP 42.3

Can't help you. The only similar errors I've seen from mdadm are "Device or resource busy" and "disk busy not available", but those aren't what you get.

Busy block device may be by LVM, multipath, mdadm and all other similar stuff.
If you fail to find what exactly keep it busy, you can use single user mode.