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

Thu Nov 26 13:35:51 UTC 2020
Simon Matter <simon.matter at invoca.ch>

> On 11/24/20 8:20 AM, Simon Matter wrote:
>> 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.
> Same setup I've been using for 15 years at least.
> Just have a standard partition size and keep using that (or multiple of
> that,
> e.g. 256GiB, then 512GiB, than 1024MiB), so to keep numbers down.

Thanks for sharing! Interesting to hear that some people did the same or
similar things as I did without knowing from each other.

IIRC initially I started to do this when I got a server with different
disk sizes and different paths to the disks. Think of some 18G disks, some
36G, some 73G and also some 146G. Now, if you have to make the storage
redundant for disk failures and also for single path failures, you get
creative how to cut the larger disks into slices and spread the mirror
pairs over the paths.

It proved to be quite flexible in the end and still allowed the extension
of the storage without any downtime. Needless to say that the expensive
hardware RAID controllers have been removed from the box and replaced by
simple SCSI controllers - because the hardware just couldn't do what was
required here.