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DELL PERC H700 and H800 Technical Guide 15
Feature
PERC H700
Integrated/Adapter
PERC H700 Modular
PERC H800 Adapter
Clustering
Card and software
stack enables High
Availability Clusters
Not supported
4.2 CacheCade
CacheCade provides cost-effective performance scaling for database-type application profiles in a
host-based RAID environment by extending the PERC RAID controller cache with the addition of Dell-
qualified Enterprise SSDs.
CacheCade identifies frequently-accessed areas within a data set and copies this data to a Dell-
qualified, Enterprise SSD (SATA or SAS), enabling faster response time by directing popular Random
Read queries to the CacheCade SSD instead of to the underlying HDD.
Supporting up to 512 GB of extended cache, CacheCade SSDs must all be the same interface (SATA or
SAS) and will be contained in the server or storage enclosure where the RAID array resides.
CacheCade SSDs will not be a part of the RAID array.
CacheCade is a standard feature on, and only available with, the PERC H700/H800 1 GB NV Cache
RAID controller.
CacheCade SSDs can be configured using the PERC BIOS Configuration Utility or OpenManage.
4.3 Cut-Through IO
Cut-through IO (CTIO) is an IO accelerator for SSD arrays that boosts the throughput of devices
connected to the PERC Controller. It is enabled through disabling the write-back cache (enable
write-through cache) and disabling Read Ahead.
4.4 Reconfiguring Virtual Disks
There are two methods to reconfigure RAID virtual disks—RAID Level Migration (RLM) and Online
Capacity Expansion (OCE). RLM involves the conversion of a virtual disk to a different RAID level. OCE
refers to increasing the capacity of a virtual disk, which can be accomplished in three ways:
If there is a single virtual disk in a disk group and free space is available, the virtual disk’s
capacity can be expanded within that free space. If a virtual disk is created and it does not use
the maximum size of the disk group, free space is available.
Free space is also available when a disk group’s physical disks are replaced by larger disks using
the Replace Member feature.
A virtual disk's capacity can also be expanded by performing an OCE operation to add more
physical disks by encompassing all available free space on a given virtual disk, adding drives
and/or migrating to a different RAID level.
When a RLM/OCE operation is complete, a reboot is not necessary. For a list of RAID level migrations
and capacity expansion possibilities, see Table 1. The source RAID level column indicates the virtual
disk level before the RAID level migration and the target RAID level column indicates the RAID level
after the operation is complete. If you configure 64 virtual disks on a controller, you cannot perform
a RAID level migration or capacity expansion on any of the virtual disks. The controller changes the
write cache policy of all virtual disks undergoing a RLM/OCE to Write-Through until the RLM/OCE is
complete.
Note: RAID level migration and expansion is not supported on RAID levels 10, 50, and 60.