Dell D17S Configurazione e specifiche - Pagina 17
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RAID (Redundant Array of Independent Disks)
For optimal performance when configuring drives as a RAID volume, Dell recommends drive models that are identical.
NOTE:
RAID is not supported on Intel Optane configurations.
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 mirrored 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.
Precision 3460 Small Form Factor supports RAID with more than one hard drive configuration.
Media-card reader
The following table lists the media cards supported by your Precision 3460 Small Form Factor.
Table 13. Media-card reader specifications
Description
Media-card type
Media-cards supported
NOTE:
The maximum capacity supported by the media-card reader varies depending on the standard of the media card
installed in your computer.
Power ratings
The following table lists the power rating specifications of Precision 3460 Small Form Factor.
Table 14. Power ratings
Description
Type
Input voltage
Values
One SD 4.0 card slot
● Secure Digital (mSD)
● Secure Digital High Capacity(mSDHC)
● Secure Digital Extended Capacity(mSDXC)
Option one
300 W (92% Efficient, 80 PLUS Platinum)
90 VAC to 264 VAC
Specifications of Precision 3460 Small Form Factor
Option two
260 W (85% Efficient, 80
PLUS Bronze)
90 VAC to 264 VAC
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