Table of Contents
Advertisement
10
DUAL (JBOD)
The DUAL or JBOD (Just a Bunch of Disks) storage policy
enables each hard drive to be seen separately as one drive.
JBOD should only be used with a port multiplier enabled
SATA host controller such as the MicroNet SATAPCIX4
eSATA-PCIX host bus adapter, or the MicroNet SATAPCIE2
eSATA-PCI Express host bus adapter. If used with a non
PM-aware eSATA host bus adapter, only a single drive is
presented (drive 0). No such limitation exists if using a
USB host connection.
FAST (RAID 0)
The FAST storage policy, also called striping or RAID 0,
presents the best data speed by using both disks in parallel.
Hard drive data segments are written to different disks
simultaneously which increases performance, but at an
increased fault sensitivity (two drive's worth of data may be
lost at a single disk fault.)
The FAST storage policy
creates a single virtual
volume that is striped
across both hard drives,
with a storage capacity
that is equal to the sum
of both hard disk drives.
SAFE (RAID 1)
The SAFE storage policy stores all data in duplicate on each
drives to protect against data loss due to drive failure. One
drive mirrors the other at all times, equivalent to RAID 1.
Every write operation goes to both drives. SAFE provides the
highest level of data fault tolerance, but halves the amount
of storage capacity because all data must be stored twice.
The resulting storage capacity of the virtual SAFE volume will
be equivalent to the size of one hard drive. If one drive fails,
the SAFE volume is still usable, but it is in a vulnerable state
because its mirrored hard drive is inaccessible. When the
offline drive is replaced, the Megadisk will begins a rebuild
process immediately to restore data redundancy.
Although the volume remains available during the rebuild
process, the volume is susceptible to data loss through
damage to the remaining drive until redundancy is restored
at the end of the rebuild and verification process.
Host access takes precedence over the rebuild process. If
you continue to use the SAFE volume during the rebuild, the
rebuild process will take a longer time to complete, and the
host data transfer performance will also be affected.
11
Hide quick links:
Advertisement
Table of Contents
