Qsan XS5224D User Manual page 237

Start Highest then Auto Tiering
This takes advantage of the both "Highest Available Tier" and "Auto Tiering" policies. "Start
Highest then Auto Tiering" sets the preferred tier for initial data allocation to the highest
performing disks with available space, and then it relocates the volume's data based on the
performance statistics and the auto-tiering algorithm. With this tiering policy, less active
data is moved to lower tiers, making room for more active data in the higher tiers. Initial
space is allocated in highest available tier first, then relocated according to hotness of the
data.
Highest Available Tier
Use this policy when quick response times are a priority. This tier is effective for volumes
which require high levels of performance whenever they are accessed. The policy starts with
the "hottest" first and places them in the highest available tier until the tier's capacity or
performance capability limit is hit. Then it places the sub LUNs into the second higher tier.
Initial space is allocated in highest available tier. Auto tiering would prioritize sub LUNs with
highest available tier selected above all other settings.
Lowest Tier
Use this policy when cost effectiveness is the highest priority. With this policy, data is
initially placed on the lowest available tier with capacity. Select this policy for volumes that
are not performance sensitive or response-time sensitive. Regardless of their activity level,
all sub LUN of these volumes will remain on the lowest storage tier available in their pool.
Data of volumes with "Lowest tier" policy would always reside in the lowest tier. Changing
policy of a volume with data in higher tiers to '"Lowest tier" would cause all its data in higher
tier to be relocated down to the lowest tier.
No Data Movement
If a volume is configured with this policy, no sub LUN provisioned to the volumes is
relocated across tiers. Data remains in its current position, but can still be relocated within
the tier. The system still collects statistics on these sub LUNs after the tiering policy is
changed. Initial space is allocated in the tier which is healthier and has more free capacity
than other tiers. No relocation would be performed in a volume which selects "No data
movement" tiering policy.
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Auto Tiering