Dell PowerVault MD1120 User manual

Optimizing the Dell
PowerVault MD1xxx
Family SAS Solution
SAS Solutions Team
Dell │SAS Solutions Team
delltechcenter.com

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This white paper is for information purposes only, and may contain typographical errors and technical
inaccuracies. The content is provided as is without express or implied warranties of any kind.
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© Copyright 2006-2008 Dell Inc. All rights reserved.
Reproduction of these materials in any manner whatsoever without the written permission of Dell Inc. is strictly
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Dell, the Dell Logo, PowerVault, PowerEdge, and OpenManage are trademarks of Dell Inc. Microsoft and
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other countries. Other trademarks and trade names may be used in this document to refer to either the entities
claiming the marks and names or their products. Dell disclaims proprietary interest in the marks and names of
others.

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TABLE OF CONTENTS
1.INTRODUCTION ...................................................................................................................................................................4
Serial Attached SCSI (SAS)....................................................................................................................................................5
2.RECOMMENDED MAINTENANCE FOR DELL POWERVAULT MD1XXX FAMILY SASSOLUTION ....................................7
3.DELL SASPRODUCT OFFERING.........................................................................................................................................8
SAS Cabling..........................................................................................................................................................................10
Physical Drive Support ........................................................................................................................................................10
Third Party Hardware Support............................................................................................................................................10
Server Support......................................................................................................................................................................10
4.POWERVAULT MD1XXX FAMILY STORAGE ENCLOSURE DETAILS...............................................................................11
Enclosure Modes..................................................................................................................................................................11
Unified Topology..................................................................................................................................................................11
Split Topology.......................................................................................................................................................................11
Daisy-Chaining Multiple PowerVault MD1xxx Family Storage Enclosures....................................................................12
PowerVault MD1xxx Family – Common Features and Capabilities................................................................................13
5.PERC5/EAND PERC6/E CONTROLLER -DETAILED FEATURES ..................................................................................17
PERC 5/E..............................................................................................................................................................................17
PERC 6/E..............................................................................................................................................................................17
Considerations when implementing a RAID Solution........................................................................................................17
Controller Features ................................................................................................................................................................................17
Capacity Requirements...........................................................................................................................................................................19
6.DELL OPENMANAGE SERVER ADMINISTRATOR.............................................................................................................21
Managing the PERC 5/E and PERC 6/E Controllers and the PowerVault MD1xxx Family Storage Enclosures.........21
Using the Create Virtual Disk Wizards...............................................................................................................................21
Reconfiguring Virtual Disks -- RAID Migration and Capacity Expansion.......................................................................22
Moving Physical Disks and Virtual Disk Configurations – Disk Roaming and Disk Migration.....................................23
Importing Migrated Virtual Disks .......................................................................................................................................24
7.STORAGE APPLICATIONS AND COMPONENTS..................................................................................................................27
Identify customer usage model and needs...........................................................................................................................27
Picking a solution based on the application profile............................................................................................................27
Application-Specific Guidelines...........................................................................................................................................30
E-Mail Servers ........................................................................................................................................................................................30
Web Servers.............................................................................................................................................................................................31
Database or Online Transaction Processing Servers...........................................................................................................................32
File Servers..............................................................................................................................................................................................34
Streaming Media Servers .......................................................................................................................................................................37
Hot Spares.............................................................................................................................................................................38
8.SUMMARY AND CONCLUSIONS ........................................................................................................................................39
APPENDIX –A:REFERENCES ....................................................................................................................................................40
9.APPENDIX –B:GLOSSARY...............................................................................................................................................41
10.APPENDIX –C:REVISION HISTORY.............................................................................................................................42

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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.
Selecting the right storage components not only impacts the effectiveness of a given application
but may also improve the performance of the entire IT infrastructure that relies on that storage. See
Table 1 for examples of key storage components.
Table 1: Examples of the components in a typical storage solution
Storage Solution Components Examples
Physical Storage Device Technology Storage Expansion Enclosure (for example,
PowerVault™MD1xxx Family and MD3xxx Family)1
Interconnect Technology 3 Gbps Serial Attached SCSI (SAS)
Host System Interface Technology Non-RAID (HBA) or RAID controllers (for example,
PowerEdge™Expandable Raid Controller)
Management Capabilities Dell™OpenManage™Server Administrator
As with many IT solutions, storage deployments can be assessed using numerous criteria, each
with varying levels of importance. In general, the effectiveness of a given storage solution should
be measured using the following attributes:
•Reliability – The solution remains functional and ensures that data is unaltered
•Availability – Data remains accessible by the application.
•Serviceability – The hardware has easy access to assemblies/components, allowing easy
maintenance and replacement.
•Redundancy – The hardware provides redundancy for both the data storage, as well as
for the hardware management capabilities.
•Performance
oBandwidth Utilization – Data throughput / available Bandwidth
oIOPS – I/Os per second
•Data Protection – Data is protected against catastrophic system failure or components
failure.
•Scalability – Storage capacity can be expanded as the application necessitates.
•Cost – Measured in total lifetime cost, acquisition cost, or $ per Gigabyte.
•Density – The storage solution provides optimal IOPS performance within a given rack
space
•Power and Cooling – Optimization of power and cooling requirements in the datacenter
1Dell PowerVault MD1xxx Family include the MD1000 and MD1120 enclosures. The Dell PowerVault MD3xxx Family
include the MD3000 and MD3000i storage arrays.

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An optimal storage solution addresses all key attributes to a greater or lesser extent depending on
their relative importance. This paper presents a study of the technological, functional and
behavioral differences of the storage solution components and measures them against the
attributes listed above. Understanding each component with respect to these attributes will help in
making informed decisions about the optimal solution for a given storage application.
The paper presumes that the reader has a basic understanding of the different RAID levels and
interconnect technologies – such as Serial Attached SCSI (SAS) and PCI Express. This paper
focuses on Serial Attached SCSI storage technology, specifically for the Dell PowerVault MD1xxx
Family (MD1000 and MD1120) storage expansion enclosures and Dell SAS RAID controllers
(PERC 5/E and PERC 6/E). Dell external RAID enclosures (MD3xxx Family) are outside the
scope of this document and are discussed under a separate paper.
Other storage technologies such as SCSI or Fibre Channel, as well as topologies such as Network
Attached Storage (NAS) or Storage Area Network (SAN), are also outside the scope of this
document. All storage applications will be treated independent of a specific host system or server.
Serial Attached SCSI (SAS)
The SCSI (Small Computing System Interface) protocol originated more than 20 years ago and is
used in the majority of server storage needs (for example, storage that is internal to a server or
physically connected to a server in an external disk expansion enclosure). The market prevalence
of SCSI has created economies of scale making it one of the most affordable storage interconnect
technologies available today. Many businesses rely on SCSI physical disks to deliver extremely
cost-effective and reliable storage. In fact, SCSI physical disks have advanced over the years
offering increased performance and more sophisticated features with each iteration. However,
given the inherent limitations of its parallel architecture, the current version of SCSI physical disks,
U320 or Ultra320, will be the last version of the traditional SCSI technology.
Serial Attached SCSI (SAS) is a major iteration of SCSI technology and introduces a host of
benefits when compared to older SCSI technology including the following features.
Dramatic improvement in bandwidth performance
•The first generation of SAS will support 3.0 Gbps (or 300 MB/sec) per “lane”
•Ultra320 SCSI is the shared-bus architecture. SAS introduces a point-to-point topology
enabling systems with many physical disks to scale bandwidth far beyond the bandwidth
capacity of Ultra320 SCSI.
Figure 1: Parallel U320 SCSI bus versus point-to-point Serial Attached SCSI connection
3.0 Gbps per lane
Up to320 MBps

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•SAS introduces the concept of port aggregation to storage interconnects. External storage
devices can connect via a x4 (by four) wide-lane. Cabling aggregates four SAS lanes, each
operating at 3.0 Gbps, for a full external connection bandwidth of up to 12.0 Gbps on a single
connector.
Figure 2: Bandwidth improvement with SAS port aggregation
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. This typically translated to maximum of 14
physical disks connected to a single SCSI channel on a RAID controller. With SAS expansion,
a single SAS port can be expanded out to multiple SAS devices (similar to how Ethernet hubs
can expand a single Ethernet connection into multiple devices).
Other important changes to keep in mind about SAS:
•SAS continues to use the SCSI command sets for driver & software compatibility.
•SAS is not backwards compatible with Parallel SCSI.
One parallel SCSI cable
Up to 320MB/s
(equal to 2.56Gb/s)
One x4 SAS cable
12 Gb/s performance

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2. Recommended Maintenance for Dell PowerVault MD1xxx Family SAS Solution
Dell strives to provide the best possible customer experience for all of our Enterprise server and
storage products. Proper maintenance of your solution is essential to ensure that the equipment
remains in optimal working condition. Dell recommends the following suggested maintenance
activities.
Keep firmware/drivers/utilities Updated
In general, Dell posts planned maintenance updates for firmware twice a year. To stay current
with the latest updates, customers can subscribe to Dell notification tools. Click the following link
to sign up for technical updates.
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 resolves possible physical disk errors that may lead to physical
disk failure and result in data integrity issues. Dell recommends implementing Background Read
Patrol in all configurations.
See section 5 for details.
Schedule and run periodic consistency checks / Background Initialization (BGI)
Consistency checks / BGI are performed by many RAID controllers to verify that all stripes in a
redundant virtual disk are consistent and to automatically correct stripes where inconsistencies are
found. BGI is a consistency check that automatically runs on all redundant arrays. Depending on
workload, Dell recommends that consistency checks should be run manually on the virtual disks at
least once every month to ensure data integrity. Consistency checks and Background Read Patrol
are complementary and both should be used.
See section 5 for details.
Enable Hot Spares
Hot spare functionality provides extra security, availability and redundancy by automatically
replacing a failed disk in a RAID group and allowing the rebuild of the degraded array to begin
immediately. Dell PERC controllers support Hot Spare functionality and it is recommended
whenever possible.
See section 5 for details.
Document your configuration and keep the documentation current
Documenting your configuration facilitates faster and easier recovery should a failure occur. Make
sure to include RAID levels, physical disks included in your virtual disks, firmware, and driver
versions and usage of hot spares in your documentation.

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Perform periodic physical inspection of your connections and cabling
Damaged cables and loose connections may cause functional issues with your storage solution.
Dell recommends a physical equipment audit two times a year or anytime after re-cabling or re-
deploying your storage hardware.
3. Dell SAS Product Offering
The PowerVault MD1xxx Family enclosures represent Dell JBOD offering. This includes both the
MD1000 and MD1120 enclosures (see Table 2). These are feature-optimized storage expansion
enclosures that use the latest industry standard storage interconnect technology, Serial Attached
SCSI (SAS). These enclosures support between 2 and 24 physical SAS drives. Along with Dell
host-based RAID controllers, PERC 5/E and PERC 6/E, the PowerVault MD1xxx Family
introduces new levels of performance, capacity, and scalability at industry leading prices.
Table 2: Summary and comparison of key features of the MD1xxx Family enclosures
Features PowerVault MD1000 PowerVault MD1120
Rack space 3U (rack only) 2U (rack only)
Drive bays 15 (3.5-inch drives) 24 (2.5-inch drives)
Supported drive types 3 Gbps SAS & 3 Gbps SATA II 3 Gbps SAS
Expandability Three shelves for a total of 45
drives per host port (unified
mode only)
Three shelves for a total of 72
drives per host port (unified
mode only)
Management In-band, using Dell
OpenManage software In-band, using Dell OpenManage software
Backplane options Unified or split JBOD Unified or split JBOD
Supported RAID
controllers PERC 5/E and PERC 6/E PERC 6/E only
Cluster support No No
Hot-pluggable drives Yes Yes
Hot-pluggable fans and
power supplies Yes (combined fan and power
supply modules)
Yes (combined fan and
power supply modules)
Enclosure management
configurations Redundant and nonredundant Redundant and
nonredundant
Fan and power supply
configuration Redundant Redundant
Supported disk array
enclosures PowerVault MD3000 and
PowerVault MD3000i N/A (designed for future
support for attachment to
external RAID enclosures)

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Primary use General-purpose storage utilizing
cost-effective, high-capacity
drives
High-performance storage for
applications requiring high I/O
or throughput rates
Major features of the PowerVault MD1xxx Family and PERC 5/E and PERC 6/E solution include:
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
12.0 Gbps connection to the host controller
•Host interconnect with the PERC 5/E and PERC 6/E host-based controllers
•RAID levels 0 and 10
•Refer to following link for specific performance information
http://www.delltechcenter.com/page/Storage
Availability
•Support for RAID levels 1, 5, 6, 10, 50, and 60
•Redundant, hot pluggable power supplies with integrated cooling fan modules
•Redundant enclosure management modules (EMMs)
•Hot pluggable physical disks
Scalability/Expandability
•Support for daisy-chaining up to three PowerVault MD1xxx Family expansion enclosures per
PERC 5/E and PERC 6/E connection
•Supports between 2 and 24 physical drives
•Supports 36GB, 73GB, 146GB, 300, and 400 GB 3.5-inch SAS physical disks (MD1000)
•Supports 250GB, 500GB, 750GB, and 1TB 3.5-inch SATA physical disks (MD1000)
•Supports 36GB, 73GB, 146GB GB 2.5-inch SAS physical disks (MD1120)
•Refer to the Dell PowerVault MD1120 System Support Matrix on www.dell.com for the latest
updates
Ease-of-Use
•Common management software with PowerEdge™ servers through Dell OpenManage Server
Administrator
PERC 5/E and PERC 6/E are the RAID controllers used to connect the PowerVault MD1xxx
Family storage enclosures to one or two PowerEdge servers. They support 3 Gbps Serial Attached
SCSI (SAS) as the storage interconnect technology and PCI Express (PCI-E) as the host-based
interconnect technology. The “E” in PERC 5/E and PERC 6/E stands for “External” because the
PERC controllers supports only physical disks that attach to a server externally.
The PERC 5/E controller offers:
•Intel IOP333 I/O processor based on Intel XScale Microarchitecture
•256MB of customized DDR2 400MHz, Error-Correcting Code (ECC) cache memory
•3 Gbps maximum speed for each SAS lane
•Two external x4 (by four) SAS ports, each aggregating 4 SAS lanes for a total bandwidth per
port of 12.0 Gbps
•x8 PCI E host interface for a total bandwidth of 32.0 Gbps
•Up to 72 hours of intelligent, transportable, battery-backed, cache memory
The PERC 6/E controller offers:

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•LSI 1078 SAS RAID-on-Chip
•256MB or 512MB of customized DDR2 667MHz, Error-Correcting Code (ECC) cache memory
•3 Gbps maximum speed for each SAS lane
•Two external x4 (“by four”) SAS ports, each aggregating 4 SAS lanes for a total bandwidth per
port of 12.0 Gbps
•x8 PCI E host interface for a total bandwidth of 32.0 Gbps
•Up to 72 hours of intelligent, transportable, battery-backed, cache memory (24-hour back-up
for 512MB memory)
For detailed information on the PERC 5/E and PERC 5/E controllers, see section 6.
SAS Cabling
The PowerVault MD1xxx Family storage enclosures and the PERC 5/E and PERC 6/E controllers
support industry standard 3.0 Gbps SAS cables in 0.6m (meter), 1m, 2m, and 4m cable lengths.
Each cable supports x4 SAS connectors to deliver up to 12.0 Gbps of total bandwidth from the host
to the enclosure. Only Dell-qualified cables are supported for connecting the PowerVault MD1xxx
Family storage enclosures to the PERC 5/E and PERC 6/E controllers.
Physical Drive Support
The PowerVault MD1xxx Family storage expansion enclosures supports the latest SAS physical
disks, currently specified as 3.0 Gbps SAS. SAS solutions from Dell include both 10,000 RPM and
15,000 RPM spindle speeds and a variety of capacities to allow customers the maximum flexibility.
The PowerVault MD1000 enclosure also supports 7200 RPM SATA drives, allowing for higher
capacity than SAS drives.
For the latest information on support for specific physical disks, please refer to the respective
PowerVault MD1000 and MD1120 System Support Matrices at the following links:
For MD1000 - http://support.dell.com/support/edocs/systems/md1000/
For MD1120 - http://support.dell.com/support/edocs/systems/md1120/
Third Party Hardware Support
To provide the best possible customer experience, Dell supports only hardware purchased direct
from Dell for the PowerVault MD1xxx Family and PERC 5/E and PERC 6/E controller. Dell
developed server and storage solutions include many thousands person-hours of engineering
testing and validation to ensure the highest product quality. For example, physical disks purchased
direct from Dell may include features not generally available to the rest of the industry. As such,
Dell supports only Dell tested and qualified hardware. Hardware purchased direct from Dell carries
the full Dell system warranty and ensures full compatibility. Materials purchased from third-party
vendors for use in Dell systems are not covered under Dell warranty and may not deliver an
acceptable customer experience.
Server Support
The PowerVault MD1xxx Family is supported on an broad line of Dell server systems. For the
latest information on support for specific servers, please refer to the respective PowerVault
MD1000 and MD1120 System Support Matrices at the following links: