Open Addressable Device Tiers


Andy Kowles, Seagate


The lack of determinism and the opaque nature of the existing Media Cache (MC) based Drive Managed Shingled Magnetic Recording (DM-SMR) and Host Aware (HA-SMR) designs have proven fatal for broad acceptance of shingled disks in enterprise storage systems. While the improved density and relatively high quality of SMR is welcome, systems designers cannot accept the latency variances and modal slowdowns inherent to SMR-related autonomous behavior, such as cache cleaning. This proposal aims to publicly fix that by exposing the MC (or other internal device tiers) via a simple block addressing scheme for system software to utilize. Tail latencies and overall performance for data the system designers designate can also be improved by creative use of the Openly Addressed Tiers (OATs) scheme presented.

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@inproceedings {203346,
author = {Andy Kowles},
title = {Open Addressable Device Tiers},
booktitle = {9th USENIX Workshop on Hot Topics in Storage and File Systems (HotStorage 17)},
year = {2017},
address = {Santa Clara, CA},
url = {},
publisher = {USENIX Association},
month = jul