Your customer has an existing HP StoreServ 7400 with four controllers. The array has only SSD drives
installed. What should you consider when sizing a solution which includes Adaptive Optimization?
A.
Ensure that 3% of the capacity and 30% of the performance can be delivered by the SAS disks.
B.
Include SAS 10/15K disks in the configuration.
C.
Add SSDs or nearline disks to a single node pair.
D.
Size the nearline tier for 30% of the performance requirement.
Explanation:
Note:
* SAS stands for Serial Attached SCSI. Basically, a SAS drive utilizes the same form factor as a SATA
drive but has several high performance advantages. First of all, there’s the platter speed. While
typical SATA drives operate at 7200RPM, a SAS drive operates at 10K or 15K. Although the platter
speed is double that of SATA, the MTBF (Mean Time Before Failure) remains at the industry standard
of 1.2 million hours.
* Make sure to define tier 0 to be on a higher performance level than tier 1, which in turn should be
higher performance than tier 2. For example, you may choose RAID 1 with SSDs for tier 0, RAID 5
with FC drives for tier 1 and RAID 6 with NL or SATA drives for tier 2.
* Best practices encourage you to begin your Adaptive Optimization configurations with your
application CPG starting with tier 1. For example, tier 1 could be CPG using your FC or SAS physical
disks. This allows you to add both higher and lower tier capabilities at a later date. If you don’t have
higher or lower tier, you can add either or both at a later date by using a new CPG, such as tier 0
using SSDs or tier 2 using NL. Or, you could have CPG tiers with RAID 1 or RAID 5 and RAID 6. Themain point is that you should begin with middle CPG tier 1 when configuring Adaptive Optimization
with your application.
* Example:
HP 3PAR Adaptive Optimization moved ~33 percent of the IOPS workload to the SSD drives even
though that involved moving only 1 percent of the space. Performance improved in two ways: the 33
percent of the IOPS that were serviced by SSD drives got very good latencies (~2 ms), and the
latencies for the NL drives also improved (from ~40 ms to ~15 ms). Moreover, the investment in the
16 SSD drives permitted them to add even more NL drives in the future, because the SSD drives have
both space and performance headroom remaining.
Reference; Adaptive Optimization for HP 3PAR StoreServ Storage