SUSE Linux Enterprise Server 12 SP4 Storage Administration Guide Storage Administration Guide SUSE Linux Enterprise Server 12 SP4 Provides information about how to manage storage devices on a SUSE Linux Enterprise Server. Publication Date: September 24, 2021 SUSE LLC 1800 South Novell Place Provo, UT 84606 USA https://documentation.suse.com Copyright © 2006– 2021 SUSE LLC and contributors. All rights reserved. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or (at your option) version 1.3; with the Invariant Section being this copyright notice and license. A copy of the license version 1.2 is included in the section entitled “GNU Free Documentation License”. For SUSE trademarks, see https://www.suse.com/company/legal/ . All other third-party trademarks are the property of their respective owners. Trademark symbols (®, ™ etc.) denote trademarks of SUSE and its aliates. Asterisks (*) denote third-party trademarks. All information found in this book has been compiled with utmost attention to detail. However, this does not guarantee complete accuracy. Neither SUSE LLC, its aliates, the authors nor the translators shall be held liable for possible errors or the consequences thereof. Contents About This Guide xii 1 Available Documentation xii 2 Giving Feedback xiv 3 Documentation Conventions xiv 4 Product Life Cycle and Support xvi Support Statement for SUSE Linux Enterprise Server xvii • Technology Previews xviii I FILE SYSTEMS AND MOUNTING 1 1 Overview of File Systems in Linux 2 1.1 Terminology 3 1.2 Btrfs 3 Key Features 4 • The Root File System Setup on SUSE Linux Enterprise Server 4 • Migration from Ext and ReiserFS File Systems to Btrfs 9 • Btrfs Administration 10 • Btrfs Quota Support for Subvolumes 10 • Btrfs send/receive 11 • Data Deduplication Support 15 • Deleting Subvolumes from the Root File System 16 1.3 XFS 17 High Scalability by Using Allocation Groups 17 • High Performance through Efficient Management of Disk Space 17 • Preallocation to Avoid File System Fragmentation 18 1.4 Ext2 18 1.5 Ext3 19 Easy and Highly Reliable Upgrades from Ext2 19 • Reliability and Performance 20 • Converting an Ext2 File System into Ext3 20 • Ext3 File System Inode Size and Number of Inodes 21 iii Storage Administration Guide 1.6 Ext4 25 1.7 ReiserFS 26 1.8 Other Supported File Systems 26 1.9 Large File Support in Linux 27 1.10 Linux Kernel Storage Limitations 29 1.11 Troubleshooting File Systems 29 Btrfs Error: No space is left on device 30 • Freeing Unused File System Blocks 31 • Btrfs: Balancing Data across Devices 32 • No Defragmentation on SSDs 33 1.12 Additional Information 33 2 Resizing File Systems 35 2.1 Use Cases 35 2.2 Guidelines for Resizing 35 File Systems that Support Resizing 36 • Increasing the Size of a File System 36 • Decreasing the Size of a File System 37 2.3 Changing the Size of a Btrfs File System 37 2.4 Changing the Size of an XFS File System 38 2.5 Changing the Size of an Ext2, Ext3, or Ext4 File System 39 2.6 Changing the Size of a Reiser File System 40 3 Using UUIDs to Mount Devices 41 3.1 Persistent Device Names with udev 41 3.2 Understanding UUIDs 41 3.3 Additional Information 42 4 Multi-tier Caching for Block Device Operations 43 4.1 General Terminology 43 4.2 Caching Modes 44 iv Storage Administration Guide 4.3 bcache 45 Main Features 45 • Setting Up a bcache Device 45 • bcache Configuration Using sysfs 47 4.4 lvmcache 47 Configuring lvmcache 47 • Removing a Cache Pool 49 II LOGICAL VOLUMES (LVM) 51 5 LVM Configuration 52 5.1 Understanding the Logical Volume Manager 52 5.2 Creating Volume Groups 54 5.3 Creating Logical Volumes 57 Thinly Provisioned Logical Volumes 60 • Creating Mirrored Volumes 61 5.4 Automatically Activating Non-Root LVM Volume Groups 62 5.5 Resizing an Existing Volume Group 63 5.6 Resizing a Logical Volume 64 5.7 Deleting a Volume Group or a Logical Volume 66 5.8 Using LVM Commands 67 Resizing a Logical Volume with Commands 70 • Dynamic Aggregation of LVM Metadata via lvmetad 72 • Using LVM Cache Volumes 73 5.9 Tagging LVM2 Storage Objects 74 Using LVM2 Tags 74 • Requirements for Creating LVM2 Tags 75 • Command Line Tag Syntax 75 • Configuration File Syntax 76 • Using Tags for a Simple Activation Control in a Cluster 77 • Using Tags to Activate On Preferred Hosts in a Cluster 78 6 LVM Volume Snapshots 81 6.1 Understanding Volume Snapshots 81 6.2 Creating Linux Snapshots with LVM 83 6.3 Monitoring a Snapshot 83 v Storage Administration Guide 6.4 Deleting Linux Snapshots 84 6.5 Using Snapshots for Virtual Machines on a Virtual Host 84 6.6 Merging a Snapshot with the Source Logical Volume to Revert Changes or Roll Back to a Previous State 86 III SOFTWARE RAID 89 7 Software RAID Configuration 90 7.1 Understanding RAID Levels 90 RAID 0 90 • RAID 1 91 • RAID 2 and RAID 3 91 • RAID 4 91 • RAID 5 91 • RAID 6 92 • Nested and Complex RAID Levels 92 7.2 Soft RAID Configuration with YaST 92 RAID Names 95 7.3 Troubleshooting Software RAIDs 96 Recovery after Failing Disk is Back Again 96 7.4 For More Information 97 8 Configuring Software RAID for the Root Partition 98 8.1 Prerequisites for Using a Software RAID Device for the Root Partition 98 8.2 Setting Up the System with a Software RAID Device for the Root (/) Partition 99 9 Creating Software RAID 10 Devices 103 9.1 Creating Nested RAID 10 Devices with mdadm 103 Creating Nested RAID 10 (1+0) with mdadm 104 • Creating Nested RAID 10 (0+1) with mdadm 106 9.2 Creating a Complex RAID 10 108 Number of Devices and Replicas in the Complex RAID 10 109 • Layout 110 • Creating a Complex RAID 10 with the YaST Partitioner 112 • Creating a Complex RAID 10 with mdadm 115 vi Storage Administration Guide 10 Creating a Degraded RAID Array 118 11 Resizing Software RAID Arrays with mdadm 120 11.1 Increasing the Size of a Software RAID 121 Increasing the Size of Component Partitions 122 • Increasing the Size of the RAID Array 123 • Increasing the Size of the File System 124 11.2 Decreasing the Size of a Software RAID 125 Decreasing the Size of the File System 125 • Decreasing the Size of the RAID Array 125 • Decreasing the Size of Component Partitions 126 12 Storage Enclosure LED Utilities for MD Software RAIDs 129 12.1 The Storage Enclosure LED Monitor Service 130 12.2 The Storage Enclosure LED Control Application 131 Pattern Names 132 • List of Devices 135 • Examples 136 12.3 Additional Information 136 IV NETWORK STORAGE 137 13 iSNS for Linux 138 13.1 How iSNS Works 138 13.2 Installing iSNS Server for Linux 140 13.3 Configuring iSNS Discovery Domains 142 Creating iSNS Discovery Domains 142 • Adding iSCSI Nodes to a Discovery Domain 143 13.4 Starting the iSNS Service 145 13.5 For More Information 145 14 Mass Storage over IP Networks: iSCSI 146 14.1 Installing the iSCSI LIO Target Server and iSCSI Initiator 147 vii Storage Administration Guide 14.2 Setting Up an iSCSI LIO Target Server 148 iSCSI LIO Target Service Start-up and Firewall Settings 148 • Configuring Authentication for Discovery of iSCSI LIO Targets and Initiators 149 • Preparing the Storage Space 151 • Setting Up an iSCSI LIO Target Group 152 • Modifying an iSCSI LIO Target Group 156 • Deleting an iSCSI LIO Target Group 156 14.3 Configuring iSCSI Initiator 157 Using YaST for the iSCSI Initiator Configuration 157 • Setting Up the iSCSI Initiator Manually 160 • The iSCSI Initiator Databases 161 14.4 Using iSCSI Disks when Installing 163 14.5 Troubleshooting iSCSI 163 Portal Error When Setting Up Target LUNs on an iSCSI LIO Target Server 163 • iSCSI LIO Targets Are Not Visible from Other Computers 164 • Data Packets Dropped for iSCSI Traffic 164 • Using iSCSI Volumes with LVM 164 • iSCSI Targets Are Mounted When the Configuration File Is Set to Manual 165 14.6 iSCSI LIO Target Terminology 165 14.7 Additional Information 167 15 Fibre Channel Storage over Ethernet Networks: FCoE 168 15.1 Configuring FCoE Interfaces during the Installation 169 15.2 Installing FCoE and the YaST FCoE Client 170 15.3 Managing FCoE Services with YaST 171 15.4 Configuring FCoE with Commands 174 15.5 Managing FCoE Instances with the FCoE Administration Tool 176 15.6 Additional Information 178 16 NVMe over Fabric 179 16.1 Overview 179 viii Storage Administration Guide 16.2 Setting Up an NVMe over Fabric Host 179 Installing Command Line Client 179 • Discovering NVMe over Fabric Targets 180 • Connecting to NVMe over Fabric Targets 180 • Multipathing 181 16.3 Setting Up an NVMe over Fabric Target 181 Installing Command Line Client 181 • Configuration Steps 181 • Back Up and Restore Target Configuration 183 16.4 Special Hardware Configuration 184 Overview 184 • Broadcom 184 • Marvell 184 16.5 More Information 185 17 Managing Multipath I/O for Devices 186 17.1 Understanding Multipath I/O 186 17.2 Hardware Support 186 Storage Arrays That Are Automatically Detected for Multipathing 187 • Tested Storage Arrays for Multipathing Support 189 • Storage Arrays that Require Specific Hardware Handlers 190 17.3 Planning for Multipathing 190 Prerequisites 190 • Disk Management Tasks 191 • Software RAIDs 191 • High-Availability Solutions 192 • Always Keep the initrd in Synchronization with the System Configuration 192 17.4 Multipath Management Tools 192 Device Mapper Multipath Module 193 • Multipath I/O Management Tools 195 • Using MDADM for Multipathed Devices 196 • The multipath Command 196 • The mpathpersist Utility 199 17.5 Configuring the System for Multipathing 200 Enabling, Disabling, Starting and Stopping Multipath I/O Services 200 • Preparing SAN Devices