A Reference Guide for Optimizing the Dell™ PowerVault™ MD1000 SAS Solution Authored By: SAS Solution Team April, 2006 rev A01
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A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 TABLE OF CONTENTS 1. INTRODUCTION ...................................................................................................................................................................4 Serial Attached SCSI (SAS)....................................................................................................................................................5 2.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 1. Introduction A complete enterprise storage solution involves various software and hardware components. A given storage project can be addressed using several approaches. Therefore, it is essential to identify optimum storage solutions for different applications.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 The paper presumes that the reader has a basic understanding of different RAID levels and interconnect technologies – such as Serial Attached SCSI (SAS) and PCI Express. In this paper, we will focus on Serial Attached SCSI storage technology, specifically for Dell’s PowerVault MD1000 storage expansion enclosure and Dell’s PERC 5/E RAID controller.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Figure 2: Bandwidth improvement with SAS port aggregation One parallel SCSI cable Up to 320MB/s performance One x4 SAS cable Up to 12.0 Gbps performance Improved capacity scalability • SAS allows for port expansion, enabling the ability to “daisy-chain” storage enclosures for dramatic improvements in capacity scalability. With Ultra320 SCSI, systems were limited to a maximum of 16 devices on a single SCSI channel.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 http://support.dell.com/support/topics/global.aspx/support/notifications/en/index?c=us&l=en&s =gen Enable Background Read Patrol Background Read Patrol, a function of the RAID controller, is an automatically scheduled background task that scans and helps resolve possible physical disk errors that may lead to physical disk failure and result in data integrity issues.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Performance • Support for 3.0 Gbps SAS physical disks (both 10,000 and 15,000 RPM) • External cable supports a SAS x4 wide-lane to achieve a total interface bandwidth of up to 12.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 For the latest information on support for specific physical disks, see the Dell Storage web site at: http://www.us.dell.com/storage/ 3rd Party Hardware support To help provide the best possible customer experience, Dell supports only hardware purchased direct from Dell for the PowerVault MD1000 and PERC 5/E controller.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Split Topology In split mode, the enclosure is divided into two logical enclosures; with each host connection accessing its own set of physical disks. The primary Enclosure Management Module (EMM) (located on the left side of the enclosure when viewed from the rear), accesses physical disk slots 7 through 14. The secondary EMM accesses physical disk slots 0 through 6.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Figure 4: Max configuration on a single PERC 5/E controller port Figure 5: Max configuration on a single PERC 5/E controller (both ports connected) PowerVault MD1000 – Common Features and Capabilities Regardless of the topology, the PowerVault MD1000 storage enclosure provides a set of common features and capabilities.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Mixing Physical Disk Capacities By supporting the mixing of physical disk of different sizes within an enclosure, the PowerVault MD1000 storage enclosure enables optimal matching of physical disk type to the requirements of multiple applications. Mixing of physical disk sizes is supported but not recommended within a single RAID group. The PowerVault MD1000 storage enclosure supports 36 GB, 73 GB, 146 GB, and 300 GB capacities for SAS.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 External SAS Cables Depending on the enclosure topology, one or two external SAS cables may be attached between the host system(s) and the PowerVault MD1000 storage enclosure. SAS cables use four active 3 Gbps SAS lanes in a single cable to deliver an aggregate of 12.0 Gbps connection. All PowerVault MD1000 SAS cables purchased from Dell have been tested and comply with the ANSI SAS 1.0 standard.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Reliability Capabilities • Thermal Reliability A fully-redundant PowerVault MD1000 storage enclosure contains four digital temperature sensors, two on the backplane and one on each EMM. In conjunction with the SES processor, the temperature sensors provide device protection against adverse thermal conditions. The PowerVault MD1000 storage enclosure is designed to operate within an ambient temperature range of 10°C (50°F) to 35°C (95°F).
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 5. PERC 5/E Controller - Detailed Features PERC 5/E is the RAID controller used to connect the PowerVault MD1000 storage enclosure with PowerEdge servers. It supports 3 Gbps Serial Attached SCSI (SAS) as the storage interconnect technology and PCI -E as the host-based interconnect technology. PERC 5/E controller supports RAID levels 0, 1, 5, 10 and 50.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS • VER A00 RAID Level Migration Changing the RAID level of a virtual disk from the existing level (e.g. RAID 1) to another level (e.g. RAID 5) is called RAID level migration. Dell recommends that data in the virtual disk be backed up before a RAID level migration is initiated.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 A global hot spare is a backup physical disk capable of replacing a failed physical disk in any virtual disk on PERC 5/E controller. The capacity of a global hot spare should be greater than or equal to the largest physical disk in all the disk groups. Dedicated Hot Spare A dedicated hot spare is a backup physical disk capable of replacing a failed physical disk in a specific PERC 5/E virtual disk.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Table 2: PERC 5/E controller features Feature Comment SAS Technology 3Gbps Host Bus Interface x8 PCI Express Internal connectors N/A External Connectors 2 RAID Levels Supported 0, 1, 5, 10, 50 Cache Size (DIMM) 256MB DDR2 Write Cache Options Write-Through, Write-Back Read Cache Options Read-Ahead, No Read Ahead BBU Battery Life Up to 72 hours Maximum Number of Virtual Disks/Controller Maximum Number of Physical Drives/
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 6. Dell OpenManage Server Administrator Dell OpenManage Server Administrator is a management application for configuring PowerEdge servers. The Server Administrator’s configuration abilities for host-based RAID and non-RAID disk storage are of particular interest for this paper. The Server Administrator enables you to perform controller and enclosure functions from a single, graphical or command line interface.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Figure 6: Screenshot of Create Virtual Disk Advanced Wizard with Disk Selection Displayed The Create Virtual Disk Express and Create Virtual Disk Advanced wizards set the virtual disk initialization to “Fast Initialize” by default.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Table 3: Virtual disk reconfiguration on the PERC 5/E RAID controller PERC 5/Controller Starting RAID Level Target RAID Level Disk Requirements RAID 0 RAID 0 Add at least one additional disk RAID 0 (on a single disk) RAID 1 Add a single disk RAID 0 RAID 5 Add at least one additional disk RAID 1 RAID 0 With or without adding additional disks RAID 1 RAID 5 Add additional disks RAID 5 RAID 0 With or without adding additiona
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 The following procedure describes how to migrate the physical disks from one controller to another: 1. Shut down the system from which the physical disks are being moved. 2. Shut down the server of the receiving controller if it does not have a preexisting virtual disk configuration. 3. Place the physical disks into the new enclosure. 4. Start up the system connected to the receiving controller. 5.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Figure 7: Physical Disk with a Foreign State The Server Administrator displays the Import Foreign Configuration task when the controller detects a foreign configuration. If you have an incomplete foreign configuration which cannot be imported, using the Clear Foreign Configuration task, erases the foreign data on the physical disks.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Figure 8: Controller Tasks Drop-down Menu With the Import Foreign Configuration and Clear Foreign Configuration Tasks Displayed Upgrading from Dell OpenManage Array Manager Dell has discontinued the release of Dell OpenManage Array Manager. Server Administrator is a replacement for Array Manager. Customers wishing to take advantage of SAS technology must upgrade their Array Manager installation to Server Administrator.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 SNMP Traps The architecture for handling SNMP traps and the Management Information Base (MIB) is different in Server Administrator than in Array Manager. You may need to modify the applications that are customized to receive SNMP traps from Array Manager. Event Numbering The numbering scheme for Storage Management alerts or events is different than the numbers used for the corresponding Array Manager events.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Picking a solution based on the application profile One of the most important factors to consider when selecting a storage solution is the type of application that will be utilizing the storage solution. This defines the overall purpose of the server/storage solution and will determine what RAID configuration will be optimal for the application. Table 5 outlines the recommended RAID solution based on the usage of the server.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 RAID 10 RAID 10 has good I/O performance, excellent availability and redundancy. The biggest drawback of RAID 10 is that it requires twice the number of physical disks needed for data. This RAID configuration should be used in situations requiring maximum availability, redundancy, and performance. RAID 5 RAID 5 has good I/O performance, data protection and requires only one additional physical disk than the number needed for data.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Table 7: Email Sever RAID Guidelines RAID Level Concatenated Application 0 1 10 5 50 E-Mail Recommended Not Recommended Possible Recommended: • RAID 10 – Recommended for mission-critical e-mail servers where availability and redundancy and/or performance are the highest priority and where reduced storage capacity is acceptable.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Table 9: Web RAID Guidelines RAID Level Concatenated Application 0 1 10 5 50 Database Recommended Not Recommended Possible Recommended: • RAID 10 – Recommended for enterprise web server solutions where availability and redundancy and performance are the highest priority, usually for stand-alone portal sites that are critical to the organization’s business.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Table 11: OLTP RAID Guidelines Application RAID Level Concatenated 0 1 10 5 50 OLTP Recommended Not Recommended Possible Recommended: • RAID 10 – Since OLTP systems are critical for most business, this RAID configuration is highly recommended due to the high availability and redundancy and good performance.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Table13: Archival File Server RAID Guidelines Application RAID Level Concatenated 0 1 10 5 50 File Archival Recommended Not Recommended Possible Recommended: • RAID 10 – Recommended due to high availability, redundancy, and good performance. • RAID 5 – Recommended for file servers that require maximum storage capacity and moderate data protection and performance.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 Recommended: • RAID 5 – Recommended for file servers that require maximum storage capacity and moderate data protection and performance. • RAID 50 – Recommended for those solutions that require a balance between storage capacity and performance. Possible: • RAID 1 – Possible solution for situations which do not require high storage capacity.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 • RAID 50 – Recommended for those solutions that require a balance between storage capacity and performance. This solution provides greater availability and redundancy but less storage capacity. • RAID 0 – While not redundant, this solution may be useful for streaming media servers that require better performance and are members of a cluster of servers where availability and redundancy are handled at a higher level.
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS Performance both availability and performance provides capacity scalability performance enable Write back cache Web Performance RAID 0 in Web Server farms provides maximum performance of all RAID levels Enable read ahead capabilities for added performance boost On-line Transaction High Availability RAID 10 provides highest availability of all RAID levels Split Topology spanning RAID 0 across channels provides better performance if daisy
A REFERENCE GUIDE FOR OPTIMIZING DELL™ MD1000 SAS SOLUTIONS VER A00 9. Appendix – A: References 1. SAS Protocol Specification (http://www.t10.org/drafts.htm#SCSI3_SAS) 2. SFF-8470 Connector Specification (http://www.sffcommittee.com/ns/index.html) 3. Beyond The 2-TB SCSI Logical Unit (http://www.dell.com/downloads/global/vectors/2004_2tblun.pdf) 10.
