Understanding endurance and performance characteristics of HP solid state drives

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Understanding endurance and performance characteristics

of HP solid state drives

Technology brief

Introduction ......................................................................................................................................... 2

SSD endurance .................................................................................................................................... 2

An introduction to endurance ............................................................................................................. 2

NAND organization ......................................................................................................................... 2

SLC versus MLC NAND ..................................................................................................................... 2

Wear-leveling and Over-provisioning .................................................................................................. 3

Minimizing write amplification ........................................................................................................... 3

Overall SSD endurance ..................................................................................................................... 3

Endurance versus reliability with SSDs ................................................................................................. 4

HP SMARTSSD Wear Gauge ............................................................................................................. 4

Integration of the SMARTSSD Wear Gauge into storage tools and utilities ............................................... 4

SMARTSSD Wear Gauge alerts and indicators .................................................................................... 6

Integration of SMARTSSD Wear Gauge with the SNMP Storage Agents ................................................. 6

SSDs and data retention ........................................................................................................................ 6

Understanding SSD performance characteristics ....................................................................................... 7

Measuring SSD performance ............................................................................................................. 7

SSD NAND organization and performance ..................................................................................... 7

Pre-conditioning an SSD for accurate performance measurements ....................................................... 7

SSD Latency ..................................................................................................................................... 8

Origins of SSD latency .................................................................................................................. 8

Using SSDs with Array Controllers ...................................................................................................... 9

Array performance scaling with SSDs .............................................................................................. 9

SSDs and RAID levels .................................................................................................................... 9

SSD and SmartArray array accelerator cache .................................................................................. 9

SATA versus SAS SSD performance .................................................................................................. 10

Conclusion ........................................................................................................................................ 10

For more information .......................................................................................................................... 11

Summary of content (11 pages)

PAGE 1
Understanding endurance and performance characteristics of HP solid state drives Technology brief Introduction ......................................................................................................................................... 2 SSD endurance .................................................................................................................................... 2 An introduction to endurance ...................................................................................
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Introduction As more organizations seek to harness the power of information, the demand for data intensive and transactional workloads such as data warehousing, real-time analytics and virtualized environments is expanding. For that reason, solid state storage technology is becoming more mainstream because it delivers the performance, energy efficiency and high density ideal for these applications.
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far more prevalent than SLC, but it has a significantly shorter lifespan in terms of erase cycles. Typically, you can erase and re-write SLC NAND up to 100,000 times before it wears out. MLC NAND comes in both consumer grade (cMLC) and enterprise grade (eMLC) implementations. You can erase and re-write eMLC NAND about 30,000 times before it wears out, while cMLC has a lifespan of about 5,000 erase/write cycles. Clearly, the use of MLC or SLC NAND significantly affects the endurance of an SSD.
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Table 1: General endurance characteristics for classes of HP SSDs Enterprise value Enterprise mainstream Enterprise performance Target Workload High read/Low write applications Equal read/write applications Unrestricted read/write applications Reliability Endurance 3 year service life @ target workloads 3 year service life @ target workloads 3-5 year service life.
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Figure 1: This is an example of the SMARTSSD Wear Gauge information displayed by the ACU. The bar gauges on the left show the Usage Remaining in percentages for each SSD. The SMARTSSD status table at the top right displays detailed information for the highlighted SSD.
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SMARTSSD Wear Gauge alerts and indicators The Wear Gauge defines certain indicators and status level metrics for an SSD’s condition. All the tools that report SMARTSSD status use these indicators consistently. Table 2 shows the indicators and the status levels they represent. Table 2: SMARTSSD Wear Gauge indicators. SMARTSSD Wear Gauge SSD Status Drive has sufficient endurance remaining Drive has reached one or more of the status metrics indicating its remaining endurance is low.
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 The SSD’s operating temperature when it was in service  The temperature you store the SSD at after removing it from service. The data retention period of an SSD is actually greater when you operate the SSD at higher operating temperatures while it is in service and store it at lower temperatures once you remove it from service. As an example, an SSD operated at 50°C and stored at 30°C should retain its data for 28 weeks if you remove it from service at the end of its rated endurance.
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 We execute 100% sequential write tests at 256 KB request size, which writes the entire capacity of the SSD at least twice. For a 200 GB drive with a throughput of 100 MB/s, we run two 33-minute test passes. As a result, the SSD is fully written and properly conditioned.  We run several hours of 100% random writes tests at 8 KB request size and 4 KBKB aligned. We continue to run the tests until the IOPS performance drops and then stabilizes.
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Using SSDs with Array Controllers SSDs perform much better than HDDs in applications requiring large, random IOPS performance. This advantage extends to the use of SSDs RAIDed behind Array Controllers. But there are some subtleties to keep in mind, including how various RAID levels affect SSD performance differently than HDDs. Array performance scaling with SSDs Just as IOPS performance scales when using multiple HDDs behind an HP Smart Array controller, the same is true for multiple SSDs.
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on the card rather than the much faster SDRAM on the memory module. This significantly affects command latency and overall storage performance. SATA versus SAS SSD performance HP offers both SATA and SAS Solid State Drives. In general, the SAS interface is more robust and features better error detection and error processing. All of our highest performing SSDs, the enterprise performance class drives, are SAS-based. But SATA SSDs may meet your performance requirements applications.
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For more information Visit the URL listed below if you need additional information. Resource description HP Solid State Storage Technology Technology brief, 2nd edition Innovative Technologies in HP ProLiant Gen8 servers Web address http://h20000.www2.hp.com/bc/docs/support/SupportManu al/c01580706/c01580706.pdf http://h20000.www2.hp.com/bc/docs/support/SupportManual/c 03227849/c03227849.pdf Technology brief HP Solid State Storage Technology www.hp.