[CentOS] Replacing SW RAID-1 with SSD RAID-1

Tue Nov 24 07:20:07 UTC 2020
Simon Matter <simon.matter at invoca.ch>

> 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...

Sure, and for large disks I even go further: don't put the whole disk into
one RAID device but build multiple segments, like create 6 partitions of
same size on each disk and build six RAID1s out of it. So, if there is an
issue on one disk in one segment, you don't lose redundancy of the whole
big disk. You can even keep spare segments on separate disks to help in
case where you can not quickly replace a broken disk. The whole handling
is still very easy with LVM on top.