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Society for Information Mgmt

SSD: Uses for Memory in Storage for Application AccelerationAndrew ReichmanSenior Analyst

Forrester Research

November 20th, 2008

3Entire contents © 2008  Forrester Research, Inc. All rights reserved.

Agenda

• The Use Case for SSD in Storage

• Nuts And Bolts Of SSD Technology

• Architectural Options for SSD and Cache

• Current Vendor Offerings

• SSD Barriers To Adoption

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The Use Case For SSD in Storage

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SSD Offers Reduced Data Access Time

• SSD storage has much lower latency than traditional hard drives

• Applications that are extremely sensitive to latency in data access are likely to benefit from SSD

• Typical applications include Online Transaction Processing (OLTP) databases

• Data being crunched heavily for analysis that is time sensitive is also a good candidate

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Nuts and Bolts of SSD Technology

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SSD can be DRAM or Flash Based

• DRAM (the same media used for server and array cache) has the highest performance profile

• But, DRAM is the most costly SSD option

• Also, DRAM is volatile, meaning it must be continuously powered to retain data

• Volatility of DRAM requires battery backup

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SSD can be DRAM or Flash Based

• Flash has lower performance than DRAM, but is less costly and is non-volatile

• The cost reduction curve for Flash is steeper

• Flash has resiliency concerns- limited read-write-erase cycle

• Flash can be SLC or MLC

• Performance can be tuned for read or write, but not both- leads to interest split path architecture

• Most current interest in SSD revolves around SLC flash

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But, any SSD Is Expensive

• There are some environments where cost is no object

• For the majority though, the cost of SSD would have to be offset by something else

• SSD can contribute to increased use of SATA

• SSD can reduce the amount of cache in arrays

• For environments that are short stroking for performance, SSD can be cost effective

• SSD often offers power savings over HDD

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Memory as Persistent Storage vs. Cache

• Vendors disagree on whether SSD should be deployed as persistent storage or as cache

• Persistent storage allows admins to use mature processes for management, often using HDD form factor SSD drives

• But, admins must manually determine what to put on persistent SSD, and it may be wasted

• Cache algorithms allow data to move in and out of memory depending on usage

• Cache could allow better utilization of resources

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Architectural Options for SSD and Cache

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SSD/Cache can be Deployed in Many Ways

• Dedicated SSD Array

• HDD/SSD Hybrid Array

• Increased Cache in Array

• Cache Appliance

• Virtualization Appliance

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Dedicated SSD Arrays Have Been Around

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Hybrid HDD/SSD Minimize Disruption

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More Cache in the Array can sit in for SSD

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Cache Appliances Create Global Pools of Memory

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Storage Virtualization Appliances Can Deploy Added Cache

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Vendor Offerings on the Market

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Nearly Every Storage Vendor is Talking SSD

Vendor Product Architecture

Compellent Storage CenterHDD form factor Persistent Storage with automated tiering

DataCore SAN Symphony High Cache Virtualization Appliance

EMCSymmetrix & Clariion HDD form factor Persistent Storage

Gear6 CacheFX Global Cache Appliance

NetApp PAM Cache Module for Arrays

NetApp SAA Global Cache Appliance

Solid Data  SD/StorageSpire Dedicated SSD Array

Texas Memory Systems RAM SAN Dedicated SSD Array

Current Offerings on the Market:

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Barriers to Adoption

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Barriers to Adoption

• Cost- SSD still commands a premium over HDD

• Identifying data for SSD is hard; performance analytics tools are weak and under-adopted

• Reliability concerns remain for Flash in enterprise

• Concerns about incompatibility of HDD error codes

• Lack of architecture consensus slows acceptance

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Recommendations

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Recommendations

• Don’t get caught in the hype

• SSD is costly, so be judicious

• Consider how you will identify which data to place on SSD in a persistent architecture

• Performance analytics is critical for SSD success

• Start with applications- if latency is the bottleneck, then SSD might be the answer

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Andrew Reichman

617.613.6172

[email protected]

Thank you

www.forrester.com