Technology considerations in selecting a direct attached storage solution for HP ProLiant Gen8 servers

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Table 4: Performance comparison of a SAS HDD with SSDs for servers
SFF SAS disk
drives (15K RPM)
Value SSD Mainstream SSD Performance
SSD
Technology 6 Gb/s SAS 3 Gb/s or
6 Gb/s SATA
MLC NAND
3 Gb/s SATA
MLC/SLC NAND
6 Gb/s SAS
MLC NAND
6 Gb/s SAS
SLC NAND
Dual port
Sequential writes
(64 KB)
160 MB/s 100 MB/s SATA MLC
225 MB/s
SAS MLC 120 MB/s
300 + MB/s
Random writes
(4 KB, 16
commands
outstanding)
300 IOPS 300 IOPS 10,000 IOPS 15,000 IOPS
Sequential reads
(64 KB)
160 MB/s 200 MB/s 230 MB/s 400 MB/s
Random reads
(4 KB, 16
commands
outstanding)
380 IOPS 30,000 IOPS 30,000 IOPS 40,000 IOPS
IO Accelerators
HP IO Accelerators are a direct attach, solid state storage system in PCIe card format for ProLiant
servers and in Mezzanine format for BladeSystem servers. I/O accelerators use SLC or MLC NAND
flash memory technology. These devices are ideal for applications requiring high transaction rates
and real-time data access such as database and database acceleration, Web servers, video,
rendering, and animation.
I/O accelerators allow applications to access them like other storage volumes. But an I/O accelerator
is both a controller and a storage device, with its own specialized driver that translates standard
block level I/O into NAND reads and writes. It delivers data directly across the PCIe bus, resulting in
lower latency in specific environments.
The I/O accelerator architecture leverages the greater bandwidth and multi-core processing
capabilities of server CPUs. An I/O accelerator can therefore achieve higher block storage
throughput and lower latencies than traditional storage. Error correction and wear-out monitoring and
prediction maintain data integrity, but RAID fault tolerance is not available in IO Accelerator
solutions. Table 5 lists some performance data for our IO Accelerators.