Data drive type
Priority
External volume* (
Low
)
7
*Displays as
External Storage
in the
Drive Type/RPM
.
Reserved pages for relocation operation:
A small percentage of pages, normally 2, are reserved
per tier to allow relocation to operate. These are the buffer spaces for tier relocation.
Tier relocation workflow:
Tier relocation is performed taking advantage of the buffer space allocated
for tier relocation, as mentioned above. Tier relocation is also performed to secure the space
reserved in each tier for new page assignment. The area is called the buffer space for new page
assignments. When tier relocation is performed, Smart Tiers reserves buffer spaces for relocation
and new page assignment.
During relocation, a tier may temporarily be assigned over 98% of capacity as well, or well under
the allowance for the buffer areas.
Execution modes for tier relocation
Execution modes when using Remote Web Console
Smart Tiers performs tier relocations using one of two execution modes: Auto and Manual. You
can switch between modes by using Remote Web Console.
Auto execution mode
In Auto execution mode, the system automatically and periodically collects monitoring data and
performs tier relocation. You can select an Auto execution cycle of 0.5, 1, 2, 4, or 8 hours, or a
specified time.
The following illustrates tier relocation processing in a 2-hour Auto execution mode:
Manual execution mode
In Manual execution mode, you can manually collect monitoring data and relocate a tier. You can
issue commands to manually:
1.
Start monitoring.
2.
Stop monitoring.
3.
Perform tier relocation.
88
Configuring thin provisioning