Dell PowerVault MD3420 - Manual (Page 121)

Creating SSD Cache
To create ssdCache command SSD read cache:
create ssdCache userLabel="ssdCacheName"
physicalDisks=(enclosureID1,drawerID1,slotID1 ...
enclosureIDn,drawerIDn,slotIDn)
[updateExistingVirtualDisks=(TRUE|FALSE)]
The ssdCacheName parameter names the cache group. Setting the updateExistingVirtualDisks
parameter to TRUE enables SSD caching for all virtual disks in the storage array.
The following restrictions apply:
• A storage array can have only one SSD cache.
• Only virtual disks created using physical disks can use the SSD cache. You cannot enable SSD cache
on snapshot (legacy) virtual disks or snapshot images.
• SSD caching does not support self-encrypting disks (SEDs).
Adding Physical Disks To Existing SSD Cache
To add to or increase the capacity of an existing SSD cache, use the set ssdCache command:
set ssdCache [ssdCacheName]
addPhysicalDisks=(enclosureID1,drawerID1,slotID1 ...
enclosureIDn,drawerIDn,slotIDn)
Removing Physical Disks From Existing SSD Cache
To remove physical disks from existing SSD Cache:
set ssdCache [ssdCacheName]
removePhysicalDisks=(enclosureID1,drawerID1,slotID1 ...
enclosureIDn,drawerIDn,slotIDn)
You cannot remove all physical disks from an SSD Cache, and at least one physical disk must remain. To
completely remove the SSD Cache, use the delete ssdCache [ssdCacheName] command.
SSD Cache Performance Modeling
SSD Cache Performance Modeling helps you determine potential performance improvement based on
different SSD cache capacities. The modeling tool provides an estimate of performance using the
following criteria:
• cache hit percentage
• average response time
To start the modeling tool from the command line:
start ssdCache [ssdCacheName]
performanceModeling
The modeling process runs in the background until you run the stop command. The file parameter is
optional. If used, it will write modeling results to the file you specify.
stop ssdCache [ssdCacheName]
performanceModeling file="filename"
Output is displayed directly on your screen, unless the file parameter is used. You can also access
modeling results using MD Storage Manager.
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