HP ML115 Drive technology overview - Page 12
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Limited airflow environments Environments subject to higher shock and vibration (up to 1000G) Environments requiring drives with lower power consumption (2 watts) HP SSDs are designed for an operational life of over three years, the typical service life for a new server. The NAND memory used in SSDs has a relatively well understood lifespan that is primarily determined by the number of write/erase cycles to which it is subjected. As a result, SSD endurance should be viewed differently from that of disk drives. A server SSD that has reached the end of its service life is almost sure to start failing once the NAND endurance limit has been exceeded, whereas a typical SAS disk drive may continue to operate for several years beyond its stated service life. SSDs do not have great data retention characteristics. An SSD removed from a system may not be readable one year later, whereas most disk drives will retain their data for a decade or more. This makes them unsuitable for use as archival storage. SSD performance Second generations HP SSDs show significant performance improvements over the first generation products from 2008. As Table 5 shows, the new midline SSDs offer performance that is equal to or better than enterprise SAS drives. SSDs truly excel at random read operations, where their performance is starting to approach over one hundred times that of disk drives. Table 5. Performance comparison of SATA/SAS drives with SSDs for servers 6 Gb/s SAS drive Value SSDs (preliminary) 2nd generation HP SATA SSDs Class Enterprise Enterprise value Enterprise mainstream Interconnects 6 Gb/s SAS-2 3 Gb/s SATA 3 Gb/s SATA Write performance 150 MB/s TBD sustained throughput @ 64 KB Write performance random IO/s 285 TBD (4 KB, Queue=16) Read performance 90 MB/s TBD sustained throughput Read performance random IO/s 340 TBD (4 KB, Queue=16) 180 MB/s 5000+ 230 MB/s 20,000 + HP SAS SSD's (preliminary) Enterprise performance 6 Gb/s SAS-2 Dual Port TBD TBD 560 MB/s Up to 100,000 Conclusion Disk technology is evolving rapidly. Hardware should be reviewed periodically to ensure that the most cost-effective solutions are deployed. Enterprise class drives with SAS interconnects and HP SAS Smart Array Controllers provide high performance storage that is the most reliable for industrystandard servers. Other technologies may be appropriate for non-mission-critical applications. Solid state drives are a rapidly evolving class of storage technology that can operate reliably in more extreme environments than traditional disk drives, and can provide random I/O performance that is far superior to traditional disk drives. 12