Technical White Paper Dell EMC PowerVault ME4 Series and Linux Abstract This document provides best practices for Dell EMC™ PowerVault™ ME4 Series storage with Red Hat® Enterprise Linux® (RHEL).
Revisions Revisions Date Description September 2018 Initial release November 2019 Updated reference to the support matrix Acknowledgments Author: Henry Wong This document may contain certain words that are not consistent with Dell's current language guidelines. Dell plans to update the document over subsequent future releases to revise these words accordingly.
Table of contents Table of contents Revisions.............................................................................................................................................................................2 Acknowledgments ...............................................................................................................................................................2 Table of contents ................................................................................................
Table of contents 3.4.2 Physical volume data alignment .......................................................................................................................26 3.4.3 Expand storage for LVM ...................................................................................................................................26 3.5 File systems ......................................................................................................................................................
Executive summary Executive summary Dell EMC™ PowerVault™ ME4 Series entry-level storage systems offer many robust hardware and software features that rival those found in more expensive storage systems. The Linux® operating system is an extremely robust, scalable, and popular enterprise-class operating system (OS) used by many organizations. PowerVault ME4 Series supports various Linux distributions. Refer to the ME4 Series Storage System Support Matrix on Dell.
ME4 Series overview 1 ME4 Series overview The ME4 Series is a next-generation, entry-level storage system that is available in three models: PowerVault ME4012, ME4024, and ME4084. Three disk expansion enclosure models are also available to provide expanded capacity: PowerVault ME412, ME424, and ME484. 1.1 Hardware features ME4 Series arrays are available with single or dual controllers.
ME4 Series overview It is recommended to choose the right RAID level that best suits the type of workloads in the environment. Review the information in ME4 Series Administrator's Guide which details the benefits of each RAID level, the minimum and maximum disks requirements, and the recommendation of RAID levels for popular workloads. 1.2.3 Thin provisioning Virtual volumes are thin provisioned in the storage system where pages are allocated only when the data is written to the volume.
ME4 Series overview 1.2.9 Command-line interface The storage system provides a full-feature command-line interface (CLI) that enables administrators to manage and configure the storage system. The CLI software is embedded in the controller modules and can be accessed through HTTPS, HTTP, SSH, Telnet over the network, or by directly connecting to the controller's serial CLI port.
Connectivity considerations 2 Connectivity considerations In a dual-controller configuration, each ME4 Series system provides up to eight host ports, four per controller, that support the following host connectivity options: • • • • All Fibre Channel All iSCSI All SAS FC/iSCSI combination - FC: ports A0, A1, B0, and B1 iSCSI: ports A2, A3, B2, and B3 Note: To make sure the host HBAs, and FC or network switches meet the support requirements, refer to the ME4 Series Support Matrix at Dell.
Connectivity considerations The following list includes key zoning rules and recommendations. • Use the point-to-point protocol to connect to a fabric switch. • Both the ME4 Series system and the Linux hosts should be connected to two different Fibre Channel switches (fabrics) for high availability and redundancy. • Name zoning using WWNs is recommended. See 2.2.1.1 and 2.2.1.2 for instruction on identifying the WWNs on hosts and the ME4 Series array.
Connectivity considerations 2.2.1.2 Identify ME4 Series FC WWNs Locate the WWN information in the ME Storage Manager or by running the interactive CLI command. Refer to the ME4 Series CLI Guide for a detailed explanation of all available CLI commands. Identify WWNs using ME Storage Manager 1. Log in to ME Storage Manager. 2. Navigate to the Home topic. 3. Hover over the host ports to display the configuration information. See Figure 1.
Connectivity considerations 2. Execute the following CLI command to show the host-port information. The following shows information for one FC port. # show ports detail Ports Media Target ID Status Speed(A) Health Reason Action ---------------------------------------------------------------------------------------A0 FC(P) 207000c0fff03b17 Up 16Gb OK Topo(C) PID SFP Status Part Number Supported Speeds -----------------------------------------------------------------PTP N/A OK FTLF8529P3BCV-1D 4G,8G,16G 2.2.
Connectivity considerations 2.2.2.1 Identify ME4 Series iSCSI port network IP addresses If the iSCSI ports are set up during the initial Easy Start wizard, the iSCSI port network information can be found under the Home topic in ME Storage Manager. Hover over the iSCSI port to see the configuration information. See Figure 2. ME Storage Manager iSCSI port information Alternatively, use the ME4 Series CLI command to display the port information. 1. Log in to the ME4 Series controller using ssh.
Connectivity considerations 2. Execute the following CLI command to show all host-port information. The following shows the output for one iSCSI port. # show ports detail Ports Media Target ID Status Speed(A) Health Reason Action ---------------------------------------------------------------------------------------------------A2 iSCSI iqn.1988-11.com.dell:01.array.bc305bf03b17 Up 10Gb OK Port Details -----------IP Version: IPv4 IP Address: 10.10.61.12 Gateway: 0.0.0.0 Netmask: 255.255.0.
Connectivity considerations 4. Verify the host has established the iSCSI sessions to all the ME4 Series iSCSI ports. The following command should display a session for each ME4 Series iSCSI port. In this example, 10.10.61.12 corresponds to A2, 10.20.61.12 corresponds to B2, 10.10.61.13 corresponds to A3, and 10.20.61.13 corresponds to B3. # iscsiadm -m node 10.10.61.12:3260,5 10.20.61.12:3260,6 10.20.61.13:3260,7 10.10.61.13:3260,8 iqn.1988-11.com.dell:01.array.bc305bf03b17 iqn.1988-11.com.dell:01.array.
Linux setup and configuration 3 Linux setup and configuration The following subsections describe best practices when working with ME4 Series arrays on Linux operating systems. This paper uses Red Hat Enterprise Linux to illustrate various Linux setup and configuration tasks. 3.1 Discover and identify ME4 Series volumes After creating and enabling host access of the LUNs in the ME4 Series system, the host operating system needs to scan for these new LUNs before they can be used.
Linux setup and configuration To reclaim LUN 0 for a regular volume, manually unmap and remap the volume in ME Storage Manager. In ME Storage Manager under the Volumes topic, right-click the desired volume and click Map Volumes. On the Map volume interface, override the LUN ID. Map wizard On the Linux host, perform a force rescan on all SCSI buses. This removes the enclosure entries and the volume is assigned to LUN 0. # rescan-scsi-bus.
Linux setup and configuration After scanning and adding the volumes on a Linux host, the volumes can be identified by either their LUN IDs or their SCSI IDs. 3.1.3.1 Identify volumes by LUN ids The LUN ID information can be found in ME Storage Manager in the Volumes topic. Select the desired volume and click the Maps tab. The LUN column reflects the assigned ID. If the volume belongs to a Volume Group, right-click the group and select View Map Details. See Figure 4.
Linux setup and configuration On the Linux host, run the lsscsi command to show the volume LUN IDs. The highlighted digits in red correspond to the LUN IDs of the volumes.
Linux setup and configuration Additional options to show SCSI IDs include using the multipath command (if device multipath is enabled), or scsi_id command. These options are detailed as follows: Option 1: Show the SCSI ID with the multipath command.
Linux setup and configuration Filter and select volumes in ME Storage Manager Export Data to CSV Review the SCSI IDs (WWNs) in the CSV file Option 2: Use the following interactive CLI command to identify ME4 Series volume SCSI IDs. 1. Log in to the ME4 controller using ssh.
Linux setup and configuration 2. Execute the CLI command to show the volume information. The following example shows volumes that match the pattern r730xd-1-* and only display the non-snapshot volumes. The details argument includes extended attributes including the WWN of the volumes.
Linux setup and configuration Note: Dell EMC recommends using the native Linux multipath solution with ME4 Series storage. 3.2.2 Configure multipath for ME4 Series storage The native Linux multipath software comes with a set of default settings for an extensive list of storage models from different vendors. The default settings allow the software to work with the ME4 Series system right out of the box.
Linux setup and configuration Note the following in the prior example: • • • • • 3.2.3 The device section identifies the ME4 Series system by its vendor and product tags. It is recommended to enable user_friendly_names. It is recommended to enable Asymmetric Logical Unit Access (ALUA). See section 3.2.3. The path_selector can either be service-time or round-robin.
Linux setup and configuration partitioning the volume wherever possible. This eases future volume expansion and reduces administration overhead for maintaining the partitions. If partitioning is required, it is recommended to align the partition on the 1 MB boundary. ME4 Series storage uses internal disk pool chunk sizes ranging from 64k to 512k. The 1 MB boundary works well because it is a multiple of the chunk size. Misalignment can result in extra I/Os to the volumes and degrades overall performance.
Linux setup and configuration • Snapshot schedules can be created on individual volumes in ME Storage Manager. Currently, it is not possible to create a schedule against a group of volumes. Therefore, it becomes a challenge to coordinate taking consistent snapshots for multiple volumes. One option is to write a script that incorporates the necessary steps to take a consistent snapshot. The following shows an example of the high-level tasks to be included in the script. a. b. c. d. e. f. g. • 3.4.
Linux setup and configuration 3.5.1 File system layout The file system can be created on top of a LUN, a LUN partition, or a logical volume within LVM. Dell EMC recommends using the whole LUN without a partition or logical volume in LVM for ease of management. If the file systems reside in LVM, follow the LVM guidelines when creating and grouping multiple file systems. 3.5.
Linux setup and configuration 3.6 Using snapshots for data protection ME4 Series storage can create multiple point-in-time snapshots of virtual volumes. This section discusses snapshots and some use cases. Consider the following when deciding to use snapshots to protect data on virtual volumes. • • • • • • • Do not enable snapshots for all volumes. Carefully consider what data requires this type of protection and plan accordingly. The maximum number of mappable snapshots per system is 1,024.
Linux setup and configuration 4. Change the snapshot volume’s UUID. This step is not necessary if step 2 has been executed. a. Use the uuidgen command to generate a new unique UUID on the host. b. For xfs, use the xfs_admin -U command to change the filesystem UUID to the new UUID. # uuidgen 09d56888-eb9f-4a8d-9e9e-bca028edf4ef # xfs_admin -U 09d56888-eb9f-4a8d-9e9e-bca028edf4ef /dev/mapper/mpathe Clearing log and setting UUID writing all SBs new UUID = 09d56888-eb9f-4a8d-9e9e-bca028edf4ef c.
Technical support and resources A Technical support and resources Dell.com/support is focused on meeting customer needs with proven services and support. Storage solutions technical documents provide expertise that helps to ensure customer success on Dell EMC storage platforms. A.1 Related resources The following ME4 Series publications and additional resources are available at Dell.com/support.
