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Smart Prefetch Smart Prefetch User Guide Issue 02 Date 2021-03-30 HUAWEI TECHNOLOGIES CO., LTD. Copyright © Huawei Technologies Co., Ltd. 2021. All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd. Trademarks and Permissions and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this document are the property of their respective holders. Notice The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS" without warranties, guarantees or representations of any kind, either express or implied. The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute a warranty of any kind, express or implied. Issue 02 (2021-03-30) Copyright © Huawei Technologies Co., Ltd. i Smart Prefetch User Guide Contents Contents 1 Introduction.............................................................................................................................. 1 2 Environment Preparations.....................................................................................................3 2.1 Server Environment................................................................................................................................................................ 3 2.2 Installing bcache-tools...........................................................................................................................................................3 3 Compiling and Installing Software..................................................................................... 5 3.1 Compiling bcache.................................................................................................................................................................... 5 3.2 Installing and Configuring bcache.....................................................................................................................................6 3.3 Installing and Configuring acache_client and hcache................................................................................................ 7 4 Using the Software............................................................................................................... 10 4.1 Setting Smart Prefetch to Start Upon System Boot..................................................................................................10 4.2 Enabling Smart Prefetch for Distributed Storage...................................................................................................... 11 4.2.1 Configuring bcache........................................................................................................................................................... 11 4.2.2 Starting the Smart Prefetch Engine............................................................................................................................ 11 4.3 Disabling Smart Prefetch for Distributed Storage..................................................................................................... 11 4.3.1 Stopping the Smart Prefetch Engine.......................................................................................................................... 12 4.3.2 Stopping bcache.................................................................................................................................................................12 4.4 Enabling the Big Data Smart Prefetch...........................................................................................................................12 4.4.1 Precautions.......................................................................................................................................................................... 12 4.4.2 Configuring bcache........................................................................................................................................................... 12 4.4.3 Starting the Smart Prefetch Engine............................................................................................................................ 15 4.5 Disabling the Big Data Smart Prefetch......................................................................................................................... 16 4.5.1 Stopping the Smart Prefetch Engine.......................................................................................................................... 16 4.5.2 Stopping bcache.................................................................................................................................................................16 4.6 Querying Versions.................................................................................................................................................................18 4.7 About acache_client and hcache Logs...........................................................................................................................18 4.8 Querying I/O Information.................................................................................................................................................. 19 4.9 Troubleshooting..................................................................................................................................................................... 20 4.9.1 Drive Faults.......................................................................................................................................................................... 20 4.9.2 Cache Drive Faults.............................................................................................................................................................20 4.9.3 sequential_cutoff Is Missing...........................................................................................................................................21 4.9.4 The bcache Device Is Abnormal After the Server Is Rebooted.......................................................................... 21 4.9.5 Failure to Automatically Register with bcache After the Server is Rebooted.............................................. 22 Issue 02 (2021-03-30) Copyright © Huawei Technologies Co., Ltd. ii Smart Prefetch User Guide Contents A Change History...................................................................................................................... 24 Issue 02 (2021-03-30) Copyright © Huawei Technologies Co., Ltd. iii Smart Prefetch User Guide 1 Introduction 1 Introduction In storage I/O-intensive scenarios such as Spark and HBase components in distributed storage and big data, the performance of accessing I/O storage devices has a significant impact on the overall service performance. Users are also concerned about the cost per gigabyte of storage devices. The contradiction between storage capacity and I/O performance will exist for a long period of time. It is a good practice to use small-capacity, high-speed storage media as cache drives. Cache drives improve the overall storage I/O performance. They store the predicted I/O data that may be accessed again so that the data can be directly obtained from the high-speed cache. Figure 1-1 and Figure 1-2 illustrate the smart prefetch software architecture for distributed storage and big data respectively. Figure 1-1 Smart prefetch software architecture for distributed storage Issue 02 (2021-03-30) Copyright © Huawei Technologies Co., Ltd. 1 Smart Prefetch User Guide 1 Introduction Figure 1-2 Smart prefetch software architecture for big data NO TE ● I/O storage devices include hard disk drives (HDDs) and solid-state drives (SSDs). ● The performance here refers to the bandwidth, latency, and number of operations per unit time for accessing I/O storage devices. ● Small-capacity, high-speed storage media may be random access memory (RAM) drives or Non-Volatile Memory express (NVMe) SSDs. The smart prefetch function uses high-speed cache drives and efficient prefetch algorithms to improve the storage I/O performance, thus improving the overall system performance in I/O-intensive scenarios. The smart prefetch function consists of the following modules: 1. Huawei smart prefetch driver in kernel mode: bcache 2. Huawei smart prefetch engine framework in user mode: acache_client 3. Huawei smart prefetch engine algorithm in user mode: hcache 4. bcache configuration tool: bcache-tools Issue 02 (2021-03-30) Copyright © Huawei Technologies Co., Ltd. 2 Smart Prefetch User Guide 2 Environment Preparations 2 Environment Preparations 2.1 Server Environment 2.2 Installing bcache-tools 2.1 Server Environment Table 2-1 Operating system (OS) requirements OS Version CentOS Linux release 7.6.1810 (AltArch) Table 2-2 Software requirements Software Version Description GCC 7.3.0 The acache_client is compiled in the GCC 7.3.0 environment. Ensure that the GCC version has been upgraded to 7.3.0. GNU Make - Default version for CentOS 7.6. bcache-tools - See 2.2 Installing bcache-tools. 2.2 Installing
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