On 23/11/2020 17:16, Ralf Prengel wrote: > Backup!!!!!!!! > > Von meinem iPhone gesendet You do have a recent backup available anyway, haven't you? That is: Even without planning to replace disks. And testing such strategies/sequences using loopback devices is definitely a good idea to get used to the machinery... On a side note: I have had a fair number of drives die on me during RAID-rebuild so I would try to avoid (if at all possible) to deliberately reduce redundancy just for a drive swap. I have never had a problem (yet) due to a problem with the RAID-1 kernel code itself. And: If you have to change a disk because it already has issues it may be dangerous to do a backup - especially if you do a file based backups - because the random access pattern may make things worse. Been there, done that... peter >> Am 23.11.2020 um 17:10 schrieb centos at niob.at: >> >> On 23/11/2020 16:49, Frank Bures wrote: >>> On 11/23/20 10:46 AM, Simon Matter wrote: >>>>> Hi, >>>>> >>>>> I want to replace my hard drives based SW RAID-1 with SSD's. >>>>> >>>>> What would be the recommended procedure? Can I just remove one drive, >>>>> replace with SSD and rebuild, then repeat with the other drive? >>>> I suggest to "mdadm --fail" one drive, then "mdadm --remove" it. After >>>> replacing the drive you can "mdadm --add" it. >>>> >>>> If you boot from the drives you also have to care for the boot loader. I >>>> guess this depends on how exactly the system is configured. >> If you can the new disks while the original 2 disks are still available then grow, add, wait, fail, remove, shrink. That way you will never loose redundancy... >> >> # grow and add new disk >> >> mdadm --grow -n 3 /dev/mdX -a /dev/... >> >> # wait for rebuild of the array >> >> mdadm --wait /dev/mdX >> >> # fail old disk >> >> mdadm --fail /dev/sdY >> >> # remove old disk >> >> mdadm /dev/mdX --remove /dev/sdY >> >> # add second disk >> >> mdadm /dev/mdX --add /dev/... >> >> # wait >> >> mdadm --wait /dev/mdX >> >> # fail and remove old disk >> >> mdadm --fail /dev/sdZ >> >> mdadm /dev/mdX --remove /dev/sdZ >> >> # shrink >> >> mdadm --grow -n 2 /dev/mdX >> >>