Hpe Smart Array Mr Cachecade; Cache - HPE Smart Array P824i-p MR Gen10 User Manual

Write IOs to RAID 1, 5, and 6 are not allowed through FastPath.

HPE Smart Array MR CacheCade

The CacheCade read and write feature eliminates the need for manually configured hybrid arrays by
intelligently and dynamically managing frequently accessed data and copying it from HDD volumes to a
higher performance layer of SSD cache. Copying the most accessed data (hot spot) to flash cache
relieves the primary HDD array from time-consuming transactions, which allows for more efficient hard
disk operation, reduced latency, and accelerated read and write speeds. With the addition of write caching
support, read/write-intensive workloads such as Exchange server, high performance computing (HPC)
applications, Web 2.0, and other IO-intensive OLTP database system workloads experience dramatic
performance improvements.
If you enable SSD caching on a logical drive, that logical drive becomes associated with an existing or
with a future CacheCade - SSD Caching logical drive.
NOTE: You can create only one CacheCade-SSD Caching logical drive as the full capacity of the logical
drive is used for the creation of CacheCade-SSD Caching logical drive.
This method has the following benefits:
• Accelerates application performance
• Provides lower latency for transactions in applications

Cache

Read policy
The read policy options for the logical drive are:
• No Read Ahead - In no read ahead mode, read ahead capability is disabled. This setting is the default
option.
• Read ahead - Read ahead capability allows the controller to read sequentially ahead of requested
data and to store the additional data in cache memory, anticipating that the data will be needed soon.
This process speeds up reads for sequential data, but there is little improvement occurs when
accessing random data.
Write policy
The write policy options for the logical drive are:
• Write Through (SSD only) - In this mode, the controller sends a data transfer completion signal to the
host when the drive subsystem has received all the data in a transaction. This mode may result in
slower performance as it does not use the controller cache.
• Write Back - In this mode, the controller sends a data transfer completion signal to the host when the
controller cache has received all the data in a transaction. This option provides a good balance
between data protection and performance as the controller switches between Write back and write
through depending on the controller status.
• Always Write Back - In this mode, the controller sends a data transfer completion signal to the host
when the controller cache receives all the data in a transaction. If you select the Always Write Back
policy and the energy pack is absent, the firmware is forced to use the Write Back policy.
26 Features