User Guide

Volumes
A volume is a portion of storage space within the NAS. Each volume is created from the storage space of a
storage pool, or of a RAID group. Volumes are used to divide and manage your storage space. QNAP NAS
devices support three different types of volume.
Volume Type
Single Static Thick Multiple Thin Multiple
Summary Best overall read/write
performance, but does
not support most
advanced features
Good balance between
performance and
flexibility
Enables you to allocate
storage space more
efficiently
Read/write speed Fastest for random writes Good Good
Flexibility Inflexible
A volume can only be
expanded by adding
extra drives to the NAS.
Flexible
A volume can easily grow
in size.
Very flexible
A volume can easily grow
in size, and unused
space can be reclaimed
and added back to the
parent storage pool.
Parent storage space RAID group Storage pool Storage pool
Number of volumes that
can be created in the
parent storage space
One One or more One or more
Initial size Size of the parent RAID
group
User-specified Zero
Storage pool space is
allocated on-demand,
data is written to the
volume. This is called
thin provisioning.
Maximum size Size of the parent RAID
group
Size of the parent
storage pool
Twenty times the amount
of free space in the
parent storage pool
The size of a thin volume
can be greater than that
of its parent storage pool.
This is called over-
allocation.
Effect of data deletion Space is freed in the
volume
Space is freed in the
volume
QTS can reclaim the
space and add it back
into the parent storage
pool.
Method of adding storage
space
• Add disks to the NAS
• Replace existing
disks with higher
capacity disks
Allocate more space from
the parent storage pool
Allocate more space from
the parent storage pool
Snapshot support (fast
backup and recovery)
No Yes Yes
Qtier (automatic data
tiering) support
No Yes Yes
QTS 4.3.4 Getting Started Guide
Storage & Snapshots 23