HP Direct Connect SAS Storage for BladeSystem Important information

Brand: HP

Model: Direct Connect SAS Storage for BladeSystem

Category: Solid state drives

Type: Important information

ISS Technology Focus

Number 14

In this issue:

Choose the right solid-

state storage solution

Efficiency of DC vs. AC

power supplies

Tip: Check Hyper-

Threading status

remotely using

Microsoft® Windows®

PowerShell

Recent publications

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Choose the right solid-state storage solution

This article describes the features and applications of HP enterprise class solid-state

drives (SSDs) and IO accelerators. A subsequent article will detail the differences in these

solid-state storage devices based on performance, latency, lifetime writes, and expected

life at 100% writes. HP solid-state storage devices are based on NAND flash memory,

which is the predominant solid-state storage technology. Before describing the features

and applications of these devices, we must explain a few important characteristics of

NAND flash memory. If you are unfamiliar with NAND architecture, read the technology

brief “Solid state storage technology for ProLiant servers” at

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01580706/c01580706.pdf.

NAND flash memory

Solid-state devices based on NAND technology have a finite amount of writes and can be

„worn out‟ over time. The life expectancy (endurance) of a SSD or IO accelerator is

dependent on the NAND technology, write workloads, and the capacity of the device.

There are two primary types of NAND flash technology, each with different endurance,

performance, densities, and costs.

•

Single-level cell (SLC) technology works by storing one of two different charge states in

each cell, representing a single bit of information.

•

Multi-level cell (MLC) technology stores two or more bits in one cell. This allows each cell to

increase storage density by 100% or more. Two-bit MLC stores one of four different charge

states in a cell. Three-bit MLC stores one of eight different charge states in a cell.

As shown in Figure 1-1, SLC NAND has higher endurance, retention, and write

performance than MLC NAND. MLC technology is the dominant NAND technology used in

consumer products where cost is a primary factor. SLC-based SSDs provide the highest

performance and endurance for enterprise server storage. MLC-based SSDs provide a

lower cost per GB solution but have lower write performance and write endurance. MLC-

based SSDs are a good option for read-intensive application environments with limited

write requirements.

Figure 1-1: SLC and MLC technologies have different endurance, retention, performance,

density, and cost.

HP Enterprise SSDs

In addition to providing high performance, SSDs are far more robust that spinning media

drives against high shock and vibration up to 1000G. HP enterprise class SSDs features

are described below.

Full Data-Path Error Detection

The higher data rates of SSDs can increase the probability that an unreported data bit

error can occur, such as a bit flipping from 1 to 0 if the SSD does not have full data-path

error detection. Enterprise class SSDs and HDDs have full data-path error detection, and

error correction in some cases.

Surprise power loss protection

Power loss protection ensures that if the drive loses power (including hot plug removal),

user data in write cache still writes to the drive and the drive can be ready in a short time.

This allows HP SSDs to avoid the lengthy metadata rebuild process required for SSDs

without power-loss protection.

SmartSSD Wear Gauge support

All HP SSDs incorporate sophisticated features to monitor SSD usage and wear. These

monitoring features enable tools that present information to you on the percentage of life

used and amount of life remaining under the workload-to-date. This information can

validate your choice of SSD for the application and help you with SSD end-of-life

planning.

IO accelerators

I/O accelerators are also based on SLC or MLC NAND flash memory technology. Like

other storage devices, I/O accelerators present themselves as standard block level

storage, allowing applications to access them like other storage volumes. However, an

I/O Accelerator is both a controller and storage device, with its own specialized driver that

translates standard block level I/O into NAND reads and writes. It delivers block I/O

directly across the PCIe bus, resulting in lower latency performance advantages in

particular environments. The I/O accelerator architecture leverages the greater bandwidth

and multi-core processing capabilities of server CPUs to achieve higher block storage

throughput and lower latencies than are possible with a traditional storage stack and drive

controller.

HP enterprise SSD and IO accelerator applications

Not all SSDs are the same, so the HP solid-state storage portfolio includes multiple products

to meet various application needs. Our portfolio consists of four classes of solid-state storage

devices: Enterprise Performance, Enterprise Mainstream, Enterprise Value, and IO

Accelerators. Each class of device meets the requirements of different applications shown in

Table 1-1. The application recommendations in the table are based on the differences in the

performance, cost, and endurance of the HP solid-state solutions. Follow these

recommendations to ensure that you choose the correct product.

Table 1-1: Enterprise solid-state storage device classes

Efficiency of DC vs. AC power supplies

HP offers 1200 W -48 V DC Common Slot Power Supplies with 90% efficiency for our

ProLiant DL360 G7, DL380 G6 and G7, and DL385 G6 and G7 servers. We also offer self-

cooled 2250 W -48 V DC power supplies with 90% efficiency specifically designed for the

HP BladeSystem c7000 Enclosure. Each c7000 enclosure can contain up to six 2250 W -

48 V DC power supplies for a maximum of 13500 W output capacity. This article will answer

some frequently asked questions from our customers about the origin of -48 V DC power

supplies and about their efficiency compared with that of today‟s AC power supplies.

Origins of the -48 V standard

The -48 V DC standard has existed for many years in the telecommunications industry

because the telecoms use large banks of -48 V DC batteries as their primary power source

(Figure 2-1). They continually charge these batteries using either AC power from the grid or

from generators if the grid fails. If the generators fail, the batteries allow the telephone

system to run until power returns.

Figure 2-1: -480 V AC to -48 V DC power distribution

The advantages of -48 V power

Interest has increased in distributing DC power in the data center because of power losses

that occur whenever conventional UPS and server power supplies convert incoming AC

power to DC. The severity of the power loss depends on the equipment. DC power

distribution improves safety, minimizes electrical losses, and improves data center

efficiency. As shown in the previous figure, DC power is isolated from the 480 V AC

supplied by the utility. This is much safer for personnel servicing equipment because arc

flash is not a concern. DC power distribution also requires fewer conversions from the utility

to the server components, which increases efficiency.

DC and AC power supplies

For several years, -48 V DC power supplies were more efficient than AC power supplies.

But today‟s AC power supplies, such as the HP Gold and Platinum Common Slot Power

Supplies, achieve efficiencies that reach or exceed 90%. In particular, HP Platinum

Common Slot Power Supplies reach 94% efficiency at 50% load. So, the power efficiency

advantage has now gone to AC power supplies.

Tip: Check Hyper-Threading status remotely using Microsoft® Windows® PowerShell

Intel

Xeon

four-core processors based on the Intel Microarchitecture Nehalem re-

introduced support for Hyper-Threading (HT) Technology, also known as simultaneous

multi-threading. HT, which is enabled by default, allows the OS to schedule two

instruction threads to each core to share its physical resources. HT can boost the

performance of some workloads, such as Internet and e-commerce applications, by as

much as 30%. But HT can also decrease the performance of applications, such as HPC,

that have high thread contention for the core‟s resources. For this reason, you may have

disabled HT Technology on some servers through the ROM Based Setup Utility (RBSU).

But in environments with hundreds or thousands of servers, it‟s difficult to remotely

determine which servers are HT-disabled. The most common options are:

•

Reboot each server and check the HT status through the RBSU

•

Both options are time-consuming. A better way to check if HT is disabled for processors

running Windows Server 2008 or Windows Vista® is to use Windows PowerShell.

PowerShell is a task automation framework. It consists of a command-line shell and

associated scripting language built on top of the .NET Framework. PowerShell provides

full access to Windows Management Instrumentation (WMI), enabling administrators to

perform tasks on local and remote servers. PowerShell scripting lets administrators

automate queries to remote servers using a comma-separated list of computer names.

To query a remote computer about the HT status of its processors, use the

Win32_Processor association class:

Get-WmiObject Win32_Processor; add -computername whatever (replace whatever with

a comma-separated list of computer names)

Each instance of Win32_Processor is a socket with properties that include

NumberOfLogicalProcessors and NumberOfCores. The NumberOfCores value

represents the number of cores for the current instance of the processor. If HT is enabled

in the BIOS for the processor, then NumberOfCores is less than

NumberOfLogicalProcessors. To determine the total number of processor instances

associated with a computer system object, use the Win32_ComputerSystemProcessor

association class.

Additional resources

Microsoft Windows PowerShell

Win32_Processor class

Recent publications

The following is a list of papers published since our last edition of the ISS Technology

Focus.

Configuring HP Integrated Lights-Out 3 with Microsoft Active Directory HOWTO, 2nd

edition

Serial Attached SCSI technologies and architectures, 4th edition

HP Insight Control for Microsoft® System Center integration overview

Serial ATA Technology, 4th edition

Effects of virtualization and cloud computing on data center networks

Optimizing GPU-based application performance for the HP for the HP ProLiant SL390s G7

server

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Legal Notices

products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as

constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein.

Intel, Intel Xeon, and Intel Itanium are trademarks of Intel Corporation in the United States and other countries.

Microsoft and Windows are US registered trademarks of Microsoft Corporation.

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HP Direct Connect SAS Storage for BladeSystem Important information

Brand: HP

Model: Direct Connect SAS Storage for BladeSystem

Category: Solid state drives

Type: Important information

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HP Direct Connect SAS Storage for BladeSystem Important information

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