Promise Technology 2-Year Extended Warranty for VessR2000 RAID Head - Manual (Page 618)

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Product Manual Technology Background
Host Cache Flushing
On the Vess subsystem, you can enable or disable host cache flushing.
When enabled, host cache flushing guards against data loss in the event of a power failure. However RAID
performance is slightly reduced.
When disabled, the Vess subsystem has greater sustained bandwidth and lower latency, which are helpful for
real-time video capture.
When you operate the Vess with host cache flushing disabled, use a UPS to protect against data loss.
Preferred Controller ID
See “Preferred Controller ID” on page 578.
P
Ower
s
Aving
Power saving is a method of conserving energy by applying specific actions to hard disk drives (HDD). After an
HDD has been idle for the set period of time, you can elect to:
• Park the read/write heads – Referred to as Power Saving Idle Time on Vess.
• Reduce disk rotation speed – Referred to as Power Saving Standby Time on Vess.
• Spin down the disk (stop rotation) – Referred to as Power Saving Stopped Time on Vess.
Power management must be:
• Set on the RAID controller. See “Making Controller Settings” on page 113 .
• Enabled on each HDD. See “Making Disk Array Settings” on page 192.
c
APAcity
c
OerciOn
This feature is designed for fault-tolerant logical drives (RAID 1, 1E, 5, 10, 50, and 60). It is generally
recommended to use physical drives of the same size in your disk arrays. When this is not possible, the system
adjusts for the size differences by reducing or coercing the capacity of the larger drives to match the smaller
ones. With Vess, you can choose to enable capacity coercion and any one of four methods.
Enable capacity coercion and choose a method, see See “Making Controller Settings” on page 113 .