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Mon, 10 Feb 2020 10:01:48 -0800 (PST) MIME-Version: 1.0 From: Muhammad Ahmad Date: Mon, 10 Feb 2020 12:01:13 -0600 Message-ID: Subject: [LSF/MM/BPF TOPIC] Multi-actuator HDDs To: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org Cc: Tim Walker Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Proofpoint-PolicyRoute: Outbound X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-10_06:2020-02-10,2020-02-10 signatures=0 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 bulkscore=0 impostorscore=0 mlxscore=0 spamscore=0 malwarescore=0 suspectscore=0 phishscore=0 lowpriorityscore=0 clxscore=1011 mlxlogscore=931 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002100134 X-Proofpoint-Spam-Policy: Default Domain Policy Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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=E2=80=99s 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=E2=80=99s 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/