User Manual

have lower capacity than the highest capacity 7,200 RPM drives. 10K and 15K drives are labelled Mission Critical or Performance
Optimized, while 7.2K are called Business Critical or Capacity Optimized. Since 7.2K drives spin slower they can have larger
platters and space for more platters in an HDD case. That allows for higher capacity drives – 16TB, 18TB, …
Random read/write task speeds are usually measured in IOPs (Input/Output operations per second) and for 15K drives can be
up to 290. That may sound like a lot but is dwarfed by IOPS (in the hundreds of thousands) available on SSDs. Here is a link to a
chart showing HDD performance characteristics: HDD_Characteristic_and_Metrics.
Depending on workload type, storage device capabilities will be prioritized differently. Below is discussed several capabilities and
the media you would select for each.
● Better performance measured in IOPS: Storage performance for random workloads is usually measured in IOPS. When
ordered in terms of general IOPS performance, choose 15K, then 10K, then 7.2K and within those SAS HDDs, NL-SAS HDDs,
and SATA HDDs.
● Better performance measured in throughput, or gigabytes per second (GB/s): Unless dealing with very heavy sequential
workloads that would benefit from flash technology, HDDs are a good choice for most sequential workloads, such as media
viewing or database logging. NAND caching can further boost the performance of HDD storage as necessary.
● Lower latency: For workloads sensitive to latency, internal storage on the server itself typically has less latency than storage
on external arrays where longer fetch times over the network can greatly add to existing storage latency. It is important to
note that SSDs present much lower latency than mechanical HDDs.
● Greater capacity: For capacity-driven workloads, such as email archives, disk-based backup, and object storage applications,
high IOPS or throughput performance may be less of a priority as compared to capacity. In this case, choose cost-efficient
HDDs, which can offer the greatest capacity at the lowest cost.
While HDDs generally provide lower performance and higher latency than SSDs, they are still an excellent option when used as
part of a complete storage strategy that balances cost per GB, capacity, application needs, and performance.
Solid State Drives (SSDs)
SSD Feature Matrix
The following table shows the types of SSD configurations on the PowerEdge R250:
Table 13. SSD feature matrix
Type Interface Form Factor Endurance Sector Security Capacity
SSD 12 Gbps SAS 2.5 MU 512e ISE 1.6 TB
SSD 12 Gbps SAS 2.5 RI 512e ISE 1.92 TB
SSD 12 Gbps SAS 2.5 RI 512e ISE 3.84 TB
SSD 12 Gbps SAS 2.5 RI 512e ISE 3.84 TB
SSD 12 Gbps SAS 2.5 WI 512e ISE 400 GB
SSD 12 Gbps SAS 2.5 RI 512e ISE 7.68 TB
SSD 12 Gbps SAS 2.5 RI 512e ISE 7.68 TB
SSD 12 Gbps SAS 2.5 WI 512e ISE 800 GB
SSD 12 Gbps SAS 2.5 MU 512e ISE 800 GB
SSD 12 Gbps SAS 2.5 RI 512e ISE 960 GB
SSD 12 Gbps SAS 2.5 RI 512e SED FIPS 1.92 TB
SSD 12 Gbps SAS 2.5 MU 512e SED FIPS 1.92 TB
SSD 12 Gbps SAS 2.5 MU 512e SED FIPS 3.84 TB
SSD 12 Gbps SAS 2.5 RI 512e SED FIPS 3.84 TB
SSD 12 Gbps SAS 2.5 MU 512e SED FIPS 960 GB
SSD 12 Gbps vSAS 2.5 RI 512e SED 1.92 TB
Storage 23