QNAP TVS-472XT 4-Bay NAS Enclosure - Manual (Page 373)

Allocation Description
Thin provisioning QTS allocates storage pool space only when needed,
such as when data is being written to the LUN.
This ensures efficient use of space but there is no
guarantee that space will be available.
5. Click Next.
6. Configure the following LUN settings.
Setting Description
LUN name • Length: 1 to 32 characters
• Valid characters: 0-9, a-z, A-Z, underscore (_)
LUN capacity Specify the maximum capacity of the LUN. The maximum capacity
depends on the LUN allocation method:
• Thick provisioning: Equal to the amount of free space in the
parent storage pool.
• Thin provisioning: 250 TB
Tip
Select Maximum to allocate all remaining free
space to the LUN.
7. Optional: Configure any of the following advanced settings.
Setting Description
Sector size Changing the sector size to 4 KB increases LUN performance for
specific applications and disk types.
Important
VMware does not currently support a 4 KB sector
size.
Alert threshold QTS issues a warning notification when the percentage of used
LUN space is equal to or above the specified threshold.
Accelerate performance with SSD
cache
The SSD cache will be used to improve LUN access performance.
Important
This setting is only available when the SSD cache is
enabled.
Report volatile write cache for data
safety
When enabled, QTS informs iSCSI initiators connected to this LUN
that volatile write-cache is being used on the NAS. As a result,
initiators might frequently tell QTS to flush cached LUN data to
disk, which increases data safety but decreases LUN performance.
FUA bit support When enabled, iSCSI initiators are able to tell QTS to flush
important cached data to disk, instead of the whole read-write
cache.
Important
Both the iSCSI initiator and the application using
the LUN must support this feature.
QTS 4.4.x User Guide
iSCSI & Fibre Channel 372