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INTRODUCTION
15
1.3 RAID Concept
1.3.1 RAID Set
A RAID set is a group of disks connected to a RAID controller. A
RAID set contains one or more volume sets. The RAID set itself
does not dene the RAID level (0, 1, 1E, 3, 5, 6, etc); the RAID
level is dened within each volume set. Therefore, volume sets are
contained within RAID sets and RAID Level is dened within the
volume set. If physical disks of different capacities are grouped
together in a RAID set, then the capacity of the smallest disk will
become the effective capacity of all the disks in the RAID set.
1.3.2 Volume Set
Each volume set is seen by the host system as a single logical de-
vice (in other words, a single large virtual hard disk). A volume set
will use a specic RAID level, which will require one or more physi-
cal disks (depending on the RAID level used). RAID level refers to
the level of performance and data protection of a volume set. The
capacity of a volume set can consume all or a portion of the avail-
able disk capacity in a RAID set. Multiple volume sets can exist in a
RAID set.
For the SATA RAID controller, a volume set must be created either
on an existing RAID set or on a group of available individual disks
(disks that are about to become part of a RAID set). If there are
pre-existing RAID sets with available capacity and enough disks for
the desired RAID level, then the volume set can be created in the
existing RAID set of the user’s choice.
Internal PCI-Express RAID Card Comparison (ARC-12XX)
1231ML 1261ML 1280ML 1280
RAID processor IOP341
Host Bus Type PCI-Express X8
RAID 6 support YES YES YES YES
Cache Memory One DDR2 DIMM (Default 256MB, Upgrade to 2GB)
Drive Support 12 * SATA ll 16 * SATA ll 24 * SATA ll 24 * SATA ll
Disk Connector 3*Min SAS 4i 4*Min SAS 4i 6*Min SAS 4i 24*SATA