If it’s just raid0 and raid1, then there’s likely not any significant CPU time or CPU overhead involved. Most southbridges or I/O controllers support mirroring directly, and md knows how to use them. Most virtualized disk controllers do this in hardware as well.
CPU overhead comes into play when you’re doing parity on a software raid setup (like md or zfs) such as in md raid5 or raid6.
If they needed data scrubbing at a single host level like zfs offers, then probably CPU would be a factor, but I’m assuming they achieve data integrity at a higher level/across hosts, such as in their distributed DB.
well we do use md raid on raid10 on nvme disks and on write heavy workloads it can quickly raise cpu usage tough (few percent) thats why I'm asking.
it might also be a problem that we have two cpu's and we probably go over multiple i/o controllers tough (and we do not care since we are not really cpu bound, so we have plenty to spare, our workload is more i/o,memory heavy
CPU overhead comes into play when you’re doing parity on a software raid setup (like md or zfs) such as in md raid5 or raid6.
If they needed data scrubbing at a single host level like zfs offers, then probably CPU would be a factor, but I’m assuming they achieve data integrity at a higher level/across hosts, such as in their distributed DB.