Owners Manual

Table 5. Storage configurations (continued)
Primary/Boot drive Form Factor
1 x 2.5 inch HDD NA
1 x Slim Optical Disk Drive CAC/PIV - Common Access Card/Personal Identification
Verification - CAC/PIV
NOTE: Supports RAID 0 and 1 with dual 2.5 " HDD. It is not available with Optane memory (Available from August 2019).
For optimal performance when configuring drives as a RAID volume, Dell recommends drive models that are identical.
RAID 0 (Striped, Performance) volumes benefit from higher performance when drives are matched because the data is split
across multiple drives: any IO operations with block sizes larger than the stripe size will split the IO and become constrained by
the slowest of the drives. For RAID 0 IO operations where block sizes are smaller than the stripe size, whichever drive the IO
operation targets will determine the performance, which increases variability and results in inconsistent latencies. This variability
is particularly pronounced for write operations and it can be problematic for applications that are latency sensitive. One such
example of this is any application that performs thousands of random writes per second in very small block sizes.
RAID 1 (Mirrored, Data Protection) volumes benefit from higher performance when drives are matched because the data is
mirror across multiple drives: all IO operations must be performed identically to both drives, thus variations in drive performance
when the models are different results in the IO operations completing only as fast as the slowest drive. While this does not
suffer the variable latency issue in small random IO operations as with RAID 0 across heterogeneous drives, the impact is
nonetheless large because the higher performing drive becomes limited in all IO types. One of the worst examples of constrained
performance here is when using unbuffered IO. To ensure writes are fully committed to non-volatile regions of the RAID volume,
unbuffered IO bypasses cache (for example by using the Force Unit Access bit in the NVMe protocol) and the IO operation will
not complete until all the drives in the RAID volume have completed the request to commit the data. This kind of IO operation
completely negates any advantage of a higher performing drive in the volume.
Care must be taken to match not only the drive vendor, capacity, and class, but also the specific model. Drives from the same
vendor, with the same capacity, and even within the same class, can have very different performance characteristics for certain
types of IO operations. Thus, matching by model ensures that the RAID volumes is comprised of an homogeneous array of drives
that will deliver all the benefits of a RAID volume without incurring the additional penalties when one or more drives in the
volume are lower performing.
When RAID is used for two non-identical drives (i.e. M.2 + 2.5 inch), performance will be at the speed of the slower drive in the
array.
Audio
Table 6. Audio specifications
Controller Realtek ALC3234
Type Four-channel high-definition audio
Speakers Two (Directional speakers)
Interface
● Universal audio jack
● High quality speakers
● Noise reducing array microphones
● Stereo headset/mic combo
Internal speaker amplifier 2W (RMS) per channel
12 System specifications