Qtier 2.0 IO Aware
Qtier 2.0 IO Aware is a feature available in QTS version 4.3.3 or later. With IO Aware, QTS reserves 25% of
the SSD tier capacity in a Qtier storage pool for faster access performance. If data in the capacity or high
speed tiers experiences a high number of read or write requests, QTS immediately moves it to reserved SSD
space instead of waiting to move it using auto-tiering. This improves random I/O performance, offering
performance similar to having an SSD cache.
Qtier and SSD Cache Comparison
Note
Qtier can be used at the same time as SSD cache.
There are three main configuration options when configuring a NAS with a mixture of HDDs and SSDs.
Configuration
SSD Usage
HDD Usage
Qtier Storage Pool
Qtier Storage Pool (combined with
HDDs)
Qtier Storage Pool (combined with
SSDs)
SSD Cache
SSD cache
HDD-only storage pool
All-SSD Storage Pool
SSD-only storage pool
HDD-only storage pool
Qtier, SSD Cache, and All-SSD Storage Pool Comparison
Qtier Storage Pool
SSD Cache
All-SSD Storage Pool
Total file storage space
High (SSDs + HDDs)
Moderate (HDDs only)
Low (SSDs only)
Maximum SSD capacity
No limit
Up to 4 TB depending on
installed memory
No limit
SSD expansion
Expand as needed
Limited by available
memory
Expand as needed
Applicable storage
Thick volumes, thin
volumes and block-based
LUNs in the pool
All volumes and LUNs on
the NAS
Volumes and LUNs
created on the SSDs
Data migration
Scheduled or when NAS
load is low
Automatic
No migration required
Data migration method
QTS writes incoming
data to the SSD tier and
moves data to different
tiers based on access
frequency.
• Write cache: QTS
writes incoming data
to the SSD cache
and then flushes the
cache to disk
periodically.
• Read cache: QTS
copies data to the
cache as it is
accessed.
No migration required
QTS 4.5.x User Guide
Storage & Snapshots
237
