[LSF/MM/BPF TOPIC] Multi-actuator HDDs

Muhammad Ahmad
2020-02-10T18:14:23Z

Background:
As the capacity of HDDs increases so is the need to increase
performance to efficiently utilize this increase in capacity. The
current school of thought is to use Multi-Actuators to increase
spinning disk performance. Seagate has already announced it’s SAS
Dual-Lun, Dual-Actuator device. [1]

Discussion Proposal:
What impacts multi-actuator HDDs has on the linux storage stack?

A discussion on the pros & cons of accessing the actuators through a
single combined LUN or multiple individual LUNs? In the single LUN
scenario, how should the device communicate it’s LBA to actuator
mapping? In the case of multi-lun, how should we manage commands that
affect both actuators?

For NVMe HDDs are namespaces the appropriate abstraction of the
multiple actuators?

We would like to share our work mapping LUNs/Actuators through LVM &
MD-RAID to study the performance characteristics and hope to get some
feedback from the community on this approach.

[1] https://www.seagate.com/solutions/mach-2-multi-actuator-hard-drive/