July 2009
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Want a quick, easy, order-of-magnitude improvement in storage performance and economics? Learn more about Flash-based SSDs.
Moore’s Law is still in effect. Processors keep getting denser, faster, and less expensive, and the multi-core era is compounding the benefits. So why is it still so difficult — and so costly — to improve application performance?
Because the performance bottleneck is I/O, not raw processing power. For today’s data-intensive applications, seek times and rotational latencies and IOPS (input/output operations per second) have become more relevant measures of application performance than CPU speeds.
Flash technology, the high-performance, power-efficient, erasable and reprogrammable memory option, can break the I/O bottleneck at an affordable price. The performance of Flash-based solid state drives (SSDs) is far better than that of traditional hard disk drives (HDDs), and the cost is far less than dynamic random access memory (DRAM), so Flash-based SSDs can fill a “sweet spot” between those technologies in terms of price/performance.
That is why Flash technology is quickly expanding its role in enterprise datacenters, and it’s why Sun has taken a leadership role in developing Flash-based products.
Flash capabilities create breakthroughs in IT architecture
In fact, Sun is the first major systems vendor to integrate Flash technology across its entire systems portfolio, including Sun Blade systems, Sun x64 systems, and Sun CoolThreads servers. And Sun’s new Flash Module, the world’s first enterprise-quality, open-standard Flash design, is now available to developers and the OpenSolaris Storage community to foster Flash innovation.
But Flash offers additional capabilities that can create true breakthroughs in IT architecture — particularly in the storage environment. For example:
- Accelerating transaction processing: When you have a high level of write-biased Flash (Flash memory that’s optimized for write operations), Flash can provide a very fast response for synchronous requests, which are very common in data-intensive transaction processing applications. Flash can be used as a buffer for these operations.
- Flash as cache: Flash can be used and managed as a Level 3 or Level 4 cache that replaces more expensive DRAM. Effectively it creates a very large secondary cache so that when something is evicted from the main memory cache it goes into a read-biased Flash-based cache, giving you the ability to have a much larger working set.
Moreover, when coupled with other Sun technologies, Flash-based SSDs can offer new approaches to building storage environments that deliver higher performance, lower power consumption, and lower total cost. And there’s no better example than the Sun’s unique “Hybrid Storage Pool” concept.
The Hybrid Storage Pool: Unprecedented price/performance
A Hybrid Storage Pool is a new approach to building storage infrastructure that places data where it can be used most effectively. It uses Flash-based SSDs as a new storage tier — a tier that sits between traditional spinning media such as 15K RPM HDDs and much faster but more expensive memory such as DRAM.
In most cases, this means enhancing the existing environment with Flash-based SSDs, as opposed to replacing older components with Flash-based devices. For example, a small number of Flash-based SSDs can be integrated into the storage pool for data caching, resulting in significant performance gains for the most I/O intensive workloads. At the same time, these Flash-based SSDs are significantly less expensive and denser than DRAM, so the combination of Flash-based SSDs, traditional HDDs, and DRAM-based devices makes the entire storage infrastructure appear much faster to applications while cutting total infrastructure costs. And the SSDs dramatically cut power consumption — by up to 80% compared to spinning disks.
Additional Sun innovations play a key role. For example, the Solaris ZFS file system takes full advantage of the cost and performance advantages of Flash-based SSDs, driving better application and file system performance.
“ When you add Flash memory SSDs to a storage system running the Solaris ZFS file system, the system
will just go faster, with no work.”
— John Fowler, Sun’s Executive Vice President, Systems.
“When you add Flash memory SSDs to a storage system running the Solaris ZFS file system, the system will just go faster, with no work,” said John Fowler, Sun’s Executive Vice President, Systems. “You get an unprecedented level of price/performance, reduce the total power consumption of your storage infrastructure, improve overall reliability — and sacrifice nothing.”
Solaris ZFS transparently caches data on SSDs, overcoming the need to modify applications. And unlike less sophisticated file systems, ZFS recognizes different media types and optimizes how it handles each type to maximize system throughput.
“The great thing about ZFS is that it does the data placement automatically, whereas with other file systems you have to manually manage which disks get mounted where, and move things back and forth,” said Mr. Fowler. “It automatically directs frequently used data to fast SSDs and less-frequently used data to slower, less expensive HDDs.”
Additional capabilities built into specific products further enhance the advantages of Flash-based SSDs. For example, the Sun Storage 7000 Series of Unified Storage Systems incorporate features that provide write-cache protection in case of a power loss, increasing reliability. These systems can also take advantage of DTrace Analytics software, which allows administrators to quickly locate and isolate problems as well as optimize storage performance and capacity utilization — all while systems continue running in production.
| The Hybrid Storage Pool combines the performance and power advantages of Flash-based SSDs with the cost advantages of high capacity HDDs and takes full advantage of the ZFS file system to eliminate the trade-offs of traditional storage infrastructure.
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When to consider a Hybrid Storage Pool
A Hybrid Storage Pool is an excellent alternative for the most demanding, I/O-intensive storage environments. But it can also address more general business issues in a wide range of scenarios. Just a couple of examples:
- Expand the business without expanding the datacenter. Many companies are simply running out of space in their corporate datacenters, whether because of surging demand for network-based services or due to datacenter consolidation. Hybrid Storage Pools can allow businesses to meet service-level agreements with significantly fewer physical disk drives. In many cases this means the business can continue to expand the quantity and quality of its services without expanding the space, power, and cooling requirements of the datacenter.
- Cut total cost of ownership for storage infrastructure. Using the Sun Storage 7000 series as the foundation for a Hybrid Storage Pool can cut TCO in several ways: it can deliver equivalent performance and better throughput without expensive, power-hungry 15K RPM drives; it can provide the same storage capacity in a fraction of the physical space required by traditional infrastructure; and it can save thousands of dollars on licensing fees compared with alternative proprietary systems.
For example, if an application environment with a 350 GB working set needs 30,000 IOPS to meet service level agreements, 100 15K RPM HDDs would be needed. If the drives are 300GB, consume 17.5 watts, and cost $750 each, this traditional environment provides the IOPS needed, has 30TB capacity, costs $75,000 to buy, and consumes 1.75 kWh of electricity.
Using a Hybrid Storage Pool, six 64 GB SSDs (at $1,000 each) provide the 30,000 IOPS required, and hold the 350GB working set. Lower cost, high-capacity drives can be used to store the rest of the data; 30 1TB 7200 RPM drives, at $689 each ($20,670) and consuming 13 watts, provide cost-effective HDD storage. The savings are dramatic: a 64% savings in purchase price, and a 77% savings in electricity consumed.
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