Understanding endurance and performance characteristics of HP solid state drives

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Table 1: General endurance characteristics for classes of HP SSDs
Enterprise value
Enterprise mainstream
Enterprise performance
Target
Workload
High read/Low write
applications
Equal read/write
applications
Unrestricted read/write
applications
Reliability
Endurance
3 year service life @
target workloads
3 year service life @
target workloads
3-5 year service life.
Unconstrained workloads
Endurance
3k – 5k NAND
program/erase cycles
25k – 30k NAND
program/erase cycles
100k – 200k NAND
program/erase cycles
Usage
environment
-Boot devices.
-Read-intensive workloads
- High IOPS applications
- Mission critical
- High IOPS applications
Because of the limitations of endurance, SSDs—unlike disk drives—have a limited service life in a
server. Once an SSD reaches that service life, you should replace it to avoid a potential data loss from
continued operation. To assist with this process, HP has developed a new SSD monitoring feature that
tracks and reports SSD endurance. It is the HP SMARTSSD Wear Gauge™.
Endurance versus reliability with SSDs
There is a distinction between endurance and reliability. Reliability deals with how often SSDs or a disk
drives fail. We usually measure this as Mean Time between Failure (MTBF). MTBF is the number of
aggregate service hours, on average, a population of storage devices operate before a failure occurs
on any one device. Fortunately, with modern server drive technology, MTBF is typically in the millions
of hours. In general, SSDs that have not reached their endurance limit are just as reliable—if not more
reliable—than traditional disk drives. But once they have reached their endurance limit, you need to
replace them in order to avoid increasing error rates and possible drive failures.
HP SMARTSSD Wear Gauge
In 2011, we implemented the SMARTSSD Wear Gauge. It uses HP-specific data generated by the SSD
controller to calculate and report SSD endurance continuously. Various HP storage tools access and
report this data, allowing you to monitor SSD endurance in real time.
Integration of the SMARTSSD Wear Gauge into storage tools and utilities
Several storage tools and utilities monitor and report the SMARTSSD Wear Gauge information. The
most prominent is the Array Configuration Utility (ACU). Figure 1 shows the Wear Gauge information
screen for an array of SSDs attached to an HP Smart Array P812 controller.