HP X1600 User Manual download pdf (Page 28)

DescriptionRAID level

Offers the best combination of data protection and performance. RAID

1+0 or drive mirroring creates fault tolerance by storing duplicate sets

of data on a minimum of four hard drives. There must be an even

number of drives for RAID 1+0. RAID 1+0(10) and RAID 1 are the

most costly fault tolerance methods because they require 50 percent

of the drive capacity to store the redundant data. RAID 1+0(10) first

mirrors each drive in the array to another, and then stripes the data

across the mirrored pair. If a physical drive fails, the mirror drive

provides a backup copy of the files and normal system operations are

not interrupted. RAID 1+0(10) can withstand multiple simultaneous

drive failures, as long as the failed drives are not mirrored to each

other.

RAID 1+0 – Mirroring and Striping

Offers the best combination of data protection and usable capacity

while also improving performance over RAID 6. RAID 5 stores parity

data across all the physical drives in the array and allows more sim-

ultaneous read operations and higher performance than data guard-

ing. If a drive fails, the controller uses the parity data and the data

on the remaining drives to reconstruct data from the failed drive. The

system continues operating with a slightly reduced performance until

you replace the failed drive. RAID 5 can only withstand the loss of

one drive without total array failure. It requires an array with a minim-

um of three physical drives. Usable capacity is N-1 where N is the

number of physical drives in the logical array.

RAID 5 – Distributed Data Guarding

Offers the best data protection and is an extension of RAID 5. RAID

6 uses multiple parity sets to store data and can therefore tolerate up

to 2 drive failures simultaneously. RAID 6 requires a minimum of 4

drives and is available only if the controller has an enabler. Writer

performance is lower than RAID 5 due to parity data updating on

multiple drives. It uses two disk for parity; its fault tolerance allows

two disks to fail simultaneously. Usable capacity is N-2 where N is

the number of physical drives in the logical array.

RAID 6– Advanced Data Guarding

(ADG)

Setting a percent full warning threshold

To receive a warning alert when storage capacity reaches a specified limit, set the percent full warning

threshold. You can set a warning threshold for any application component, user-defined application,

and shared folder that ASM manages. An iSCSI LUN application will not have a warning threshold.

By default, the warning threshold is set to 80%. To change it, enter a new percent value on the

Advanced window.

After you set a warning threshold, ASM changes the status indicator for the application component,

user-defined application, or shared folder when this threshold has been surpassed. This is a warning

only; no hard limits are enforced on storage capacity as a result of setting this value. The warning is

visible in these places:

• A yellow warning icon appears on the application component, user-defined application, or shared

folder icon in the content pane.

• As an alert in the Properties window.

Hosting storage for applications and shared folders28

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HP X1600 User Manual Page 28

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