Ncq; Smart Mode - Accusys TShare A16T3-Share User Manual

5.5.2 NCQ

Native Command Queuing (NCQ) is an extension of the Serial ATA protocol allowing
hard disk drives to internally optimize the order in which received read and write
commands are executed. This can reduce the amount of unnecessary drive head
movement, resulting in increased performance (and slightly decreased wear of the
drive) for workloads where multiple simultaneous read/write requests are outstanding.
The figure above illustrates the access sequence in NCQ and non-NCQ mode. The
content sequences of the two hard disks are the same: 1, 2, 3, 4. However, the access
sequence in NCQ mode may vary to improve the performance.

5.5.3 SMART Mode

S.M.A.R.T. is a monitoring system of disk drives to detect and report on various
indicators of reliability, in the hope of anticipating failure. Accusys RAID system
supports S.M.A.R.T. Once this function is selected, you can select the check interval
from the drop-down list. Choose from 1 minute to 8 hours for SMART Mode to be
active. The RAID controller will command each hard disk to perform S.M.A.R.T.
according to the check interval selected. The check results will be shown as an Event
message in the main menu.
When running S.M.A.R.T. mode, the performance of the system will be slightly
affected. The higher the check frequency, the more the sequential accesses are
affected. It is recommended to turn off S.M.A.R.T. if high performance required. On the
other hand, running S.M.A.R.T. constantly allows you to monitor the conditions of hard
disks at any time.
The options of time to check disk's S.M.A.R.T are 1,15,30,60 minutes and 2,4,8
hours. We strongly suggest set to 8 hours. Frequently checking will reduce the life
time of hard drives