Access time is virtually nonexistent on most flash SSDs, and it shows in our access time test results. Keep in mind that these hard drives are still among the fastest you can get when it comes to I/O and access time, but 0.22 ms on the Samsung 470-series versus 6+ ms on the Fujitsu hard drives is a huge difference.
Write access time is more similar, mostly because of LSI’s RAID controller helping to tweak write access on the hard drives.
4K Random Read/Write I/O Performance
Reading or writing 4 KB blocks in a random fashion remains one of the most important tests because 4 KB blocks are common in x86 system memory page sizes and file system clusters.
SSDs, especially those with multi-level cell (MLC) NAND flash, are extremely fast when it comes to random read performance. We see this with the dual SSD RAID setup being almost 25 times faster than eight 15 000 RPM hard drives.
Random writes are more difficult for MLC SSDs. Writes entail a read-erase-modify-write cycle, even if only 4 KB in a larger block gets modified. This takes time, so the performance difference with conventional hard drives is smaller, but it’s still 2.2x.
- The Business Storage Revolution
- SSD Developments
- The SSD: Samsung 470-Series (MZ-SPA256, 256 GB)
- The HDDs: Fujitsu MBA3147RC (147 GB, 15 000 RPM)
- Can RAID Beat The SSD?
- Test Setup
- Benchmark Results: Access Time And 4K Random Read/Write
- Benchmark Results: Read/Write Throughput And Streaming
- Benchmark Results: I/O Performance
- Benchmark Results: PCMark Vantage Application Performance
- Benchmark Results: System Power Requirement
- Benchmark Results: Performance Per Watt Efficiency