Dell Dimension E520 - Manual (Page 28)

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Setting Up and Using Your Computer
Verifying That RAID Is Working
Your computer displays information pertaining to your RAID configuration at startup, before loading the
operating system. If RAID is not configured, the message
none defined will be displayed under RAID
Volumes, followed by a list of the physical drives installed in your system. If a RAID volume is identified,
you can then check the Status field to determine the current state of your RAID configuration. The
Status field contains information about the following conditions:
• Normal — Your RAID configuration is functioning properly.
• Degraded — One of your hard drives has failed. The computer is still bootable; however, RAID is not
functioning and data is not being copied to the other drive.
• Rebuild — Following a degraded condition, the computer has detected the replacement/connection of
a secondary hard drive and will automatically restore the RAID configuration the next time the
operating system loads.
RAID Level 1
RAID level 1 uses a data-redundancy storage technique known as "mirroring." When data is written to the
primary drive, the data is then duplicated—or mirrored—on the other drive. A RAID level 1 configuration
sacrifices high-data access rates for its data redundancy advantages.
If a drive failure occurs, subsequent read and write operations are directed to the surviving drive. A
replacement drive can then be rebuilt using the data from the surviving drive. Also, because data is
duplicated on both drives, two 120-GB RAID level 1 drives collectively have a maximum of 120-GB on
which to store data.
hard drive 1
segment 1
segment 2
segment 3
hard drive 2
segment 4
segment 5
segment 6
segment 1 duplicated
segment 2 duplicated
segment 3 duplicated
segment 4 duplicated
segment 5 duplicated
segment 6 duplicated
serial ATA RAID
configured for
RAID level 1