SanDisk thrusts SSD into the client OEM battlefield
Taking on Hitachi, Intel, Plextor and the gang
SanDisk has dived into the client OEM flash drive jungle with its latest X100 SSD.
SanDisk bought SSD controller company Pliant last year and that company's Lightning SSD products provide SanDisk with its enterprise server-class products. Now it has introduced its X100 line of client SSDs – PC, notebook and ultrabook – which do not appear to use Pliant controllers.
We have obtained fuller details of the device and its speeds and feeds are:
- 32GB, 64GB, 128GB, 256GB and 512GB capacity points;
- 24nm, 2-bit MLC NAND from, we assume, Toshiba;
- Random read/write IOPS (4K blocks) are 38,000 and 22,000;
- Sequential read/write bandwidth of 500MB/sec and 420MB/sec;
- 6Gbit/s SATA interface for 2.5-inch form factor;
- 2 million hours MTBF; and
- mSATA and customisable other form factors for ultrabook devices.
The X100 features include a 3-tier hierarchical storage structure of volatile cache (DRAM is El Reg's guess), SanDisk's non-volatile nCache and bog-standard flash. The idea is that the nCache improves random write performance, by storing written 4K blocks – which are typically written in intermittent bursts – in a dedicated single level cell (SLC) region of the flash, assuming the same architecture as the existing U100 tablet SSD.
SanDisk says the nCache can be emptied in less busy times, and asserts: "For a typical everyday use, the write performance that the users see is the nCache (burst) high performance, and not steady state (sustained) ... performance." In other words, random write performance would worsen if the nCache filled up.
Overall: "Data pattern streams are ... monitored and rearranged by a proprietary innovative multi-streaming feature that reduces fragmentation and improves locality of data. This enables fast user response, no stuttering, better multitasking capabilities and significantly improves the drive’s long-term data endurance6, ensuring an enhanced user experience."
A patrol read mechanism does background read checks with error correction. The X100 can adjust its performance to fit within different power classes or envelopes.
SanDisk says the X100, with its TRIM support, can endure 80TB being written (TBW) to it, assuming what it calls a 128GB typical Windows 7 workload. The company says: "Data is written using typical PC transfer size, written at a constant rate over the life of the SSD, and data is retained for at least 1 year upon TBW exhaustion. Based on SanDisk internal measurements, a typical client PC user writes 4GB/day."
The X100 has a 2 million hours mean time between failure rating.
Okay, so how does the X100 compare to some other client MLC SSDs that OEMs could choose?
- Hitachi GST's Ultrastar SSD400M does 56,000/24,000 random read/write IOPS – significantly better; 495/385MB/sec sequential read writes – a little worse; and 7.3PB lifetime writes – significantly better.
- Intel's 520 does 50,000/42,000 random read/write IOPS – significantly better; 550/520MB/sec seq read/writes – rather better, but we don't know its endurance, although there's a 1.2 million hours MBTF – which is not so good.
- Plextor's M3 does 70,000/65,000 random read/write IOPS (wow!); 525/445MB/sec seq read/writes – a bit better; and has a 5-year warranty as well as claiming a lowest annual failure rate of 0.05 per cent.
Based on these spec sheet numbers, the X100 is a long way from being an IOPS leader, or a MB/sec leader – although it has good sequential bandwidth numbers – and isn't an endurance leader in TBW terms. It appears the nCache feature is not delivering that significant a boost to random write speed and the X100's random IOPS numbers don't shine in this company.
SanDisk must think that when potential OEMs make more detailed comparisons, the X100's mix of features at the various capacity points and prices will win the day. ®
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