News
6/12/2008
03:05 PM
George Crump
George Crump
Commentary
Connect Directly
RSS
E-Mail
50%
50%

Flash Vs. RAM Solid State Disks

As major vendors ready for entry into the solid-state disk (SSD) market with Flash memory systems, don't count out the traditional RAM SSD. Even though RAM SSDs are more expensive per capacity, companies like Texas Memory Systems are seeing continued growth in RAM-based SSD systems. Why? RAM SSDs have two advantages: speed and reliability.

As major vendors ready for entry into the solid-state disk (SSD) market with Flash memory systems, don't count out the traditional RAM SSD. Even though RAM SSDs are more expensive per capacity, companies like Texas Memory Systems are seeing continued growth in RAM-based SSD systems. Why? RAM SSDs have two advantages: speed and reliability.In the SSD market, speed is king and for customers needing to squeeze every ounce of I/O out of their systems, RAM SSD is still the only way to go. The answer is in the numbers. For comparison, a typical mechanical hard disk drive does 4- to 5-millisecond reads and writes and can sustain about 150 to 300 random I/O's per second.

The typical Flash SSD completes reads in about 200 microseconds (0.2 milliseconds) and 100,000 random read I/O's per second; very impressive when compared with disk. In read-heavy applications, you will see a significant performance increase. Writes, however, are as high as 2 milliseconds and can sustain up to 25,000 random write I/O's per second. While you will still see a performance increase on writes with some Flash SSD vs. hard disks, they're most impressive from a read-performance perspective.

RAM SSD, on the other hand, is significantly faster at both read and write operations. It performs 15-microsecond (0.015 milliseconds) reads and writes and 400,000 random I/O's per second. Significant performance improvement can be seen on both types of operations. The challenge with RAM SSD is that you are dealing with smaller capacity -- 128 GB is typical, but smaller sizes aren't uncommon. You are looking for applications that have specific files that can be moved to the SSD; redo logs, undo segments, indices, and frequently accessed tables are great examples.

Flash SSD has another write-related issue; it can only handle so many. The typical range for Flash SSD is around 1 million to 5 million write cycles. For most applications, this is many years worth of writes. Most enterprise Flash SSDs are made up of multiple Flash modules. Having multiple Flash modules is essential to delivering maximum bandwidth and high availability through RAID protection. Flash SSDs aren't a good fit for latency-sensitive, write-intensive applications; for example, accelerating redo logs, undo segments, and enterprise messaging.

For many applications, Flash SSDs will offer significant and affordable performance increases, but when you need more performance or have legitimate concerns about a high-write application, RAM SSDs are the way to go.

George Crump is founder of Storage Switzerland, an analyst firm focused on the virtualization and storage marketplaces. It provides strategic consulting and analysis to storage users, suppliers, and integrators. An industry veteran of more than 25 years, Crump has held engineering and sales positions at various IT industry manufacturers and integrators. Prior to Storage Switzerland, he was CTO at one of the nation's largest integrators.

Comment  | 
Print  | 
More Insights
Register for Dark Reading Newsletters
White Papers
Flash Poll
Current Issue
Cartoon
Threat Intel Today
Threat Intel Today
The 397 respondents to our new survey buy into using intel to stay ahead of attackers: 85% say threat intelligence plays some role in their IT security strategies, and many of them subscribe to two or more third-party feeds; 10% leverage five or more.
Video
Slideshows
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2013-6306
Published: 2014-08-22
Unspecified vulnerability on IBM Power 7 Systems 740 before 740.70 01Ax740_121, 760 before 760.40 Ax760_078, and 770 before 770.30 01Ax770_062 allows local users to gain Service Processor privileges via unknown vectors.

CVE-2014-0232
Published: 2014-08-22
Multiple cross-site scripting (XSS) vulnerabilities in framework/common/webcommon/includes/messages.ftl in Apache OFBiz 11.04.01 before 11.04.05 and 12.04.01 before 12.04.04 allow remote attackers to inject arbitrary web script or HTML via unspecified vectors, which are not properly handled in a (1)...

CVE-2014-3525
Published: 2014-08-22
Unspecified vulnerability in Apache Traffic Server 4.2.1.1 and 5.x before 5.0.1 has unknown impact and attack vectors, possibly related to health checks.

CVE-2014-3563
Published: 2014-08-22
Multiple unspecified vulnerabilities in Salt (aka SaltStack) before 2014.1.10 allow local users to have an unspecified impact via vectors related to temporary file creation in (1) seed.py, (2) salt-ssh, or (3) salt-cloud.

CVE-2014-3594
Published: 2014-08-22
Cross-site scripting (XSS) vulnerability in the Host Aggregates interface in OpenStack Dashboard (Horizon) before 2013.2.4, 2014.1 before 2014.1.2, and Juno before Juno-3 allows remote administrators to inject arbitrary web script or HTML via a new host aggregate name.

Best of the Web
Dark Reading Radio
Archived Dark Reading Radio
Three interviews on critical embedded systems and security, recorded at Black Hat 2014 in Las Vegas.