Table of Contents
Advertisement
Rebuild and Hot Swap Functions
Rebuild
In Mirror mode, if one of the HDDs fails and is replaced with a functional HDD, the
RAID System will automatically rebuild the target HDD (the new functional HDD) with
data from the source HDD (the remaining functional HDD) sector by sector. After the
rebuild is complete, data in both HDDs will be identical. The use of two identical
HDDs from the same manufacturer, having the same capacity and RPM is
highly recommended.
Online Rebuild vs. Offline Rebuild
In most cases, Rebuild refers to "Online Rebuild", meaning the rebuild is initiated
when the RAID System is connected to the host. Due to the chipset, some systems
also support an Offline Rebuild function. After an Online Rebuild is activated and the
RAID System rebuild begins, even if the RAID System loses connection to the host,
the rebuild continues. If the RAID System is powered off, the RAID System will retain
the rebuild status in memory. When the RAID System is powered on again, the
rebuild process will resume from the previous status. If the Online Rebuild is not
activated initiating the rebuild, the RAID System cannot be rebuilt when not
connected to the host.
Rebuild Type by RAID System
eSATA/USB 2.0 Model - Online Rebuild
USB 2.0 Model - Online Rebuild
USB 2.0/FireWire 800 Model - Online/Offline Rebuild
Rebuild Existing Data to a Backup HDD
Due to the Rebuild behavior, the first HDD inserted into one of the HDD trays and
recognized by the RAID System becomes the source HDD. To rebuild existing data
from a source HDD to a backup HDD (target HDD), the source HDD must first be
inserted into one of the two HDD. After the host detects the source HDD (in 10 to 15
seconds), and the RAID System indicates the target HDD tray is empty via the LED
disk error light, the target HDD should then be inserted in the other HDD tray. The
RAID System will then recognize the target HDD, the disk error LED will stop, and the
rebuild process will begin automatically. These actions ensure that the RAID System
recognizes the correct source and target HDDs and to prevent the source data from
being overwritten.
Rebuild Speed
eSATA/USB 2.0 Model - 30 MB/sec (approximate)
USB 2.0 Model and USB 2.0/FireWire 800 Model - 2 MB/sec (approximate)
Note: The rebuild speed of the USB 2.0 Model and USB 2.0/FireWire 800 Model is
slow. Thus, accessing the HDD during a rebuild is not recommended.
23
Advertisement
Table of Contents
