Appendix B - RAID Features
RAID Levels
The controller supports RAID levels 0, 1, 5 and 10.
NOTE: RAID level 1 and RAID level 10 are functionally equivalent. RAID level 1 is used when the RAID is built with 2 drives, RAID level 10 when more than 2 drives are used.
Logical Volumes
The controller supports up to 1024 independent logical volumes. Each logical volume will be identified by a LUN. The controller only supports a single node name.
RAID Creation
RAIDs and logical volumes are created and managed using the Raidtec Manager management software. When a RAID level 5 is created, the parity in the volume must be initialized. The RAID controller will read every stripe, calculate parity and write the parity. This can take several hours depending on the capacity of the disks. The RAID is made available from when it is created, but full performance is not achieved until the RAID is fully initialized.
NOTE: 2 GB of each disk is reserved for reallocated blocks by the controller. Therefore the capacity formed will be slightly less than the nominal capacity available from the drives.
NOTE: Usable drive capacities are fixed to allow drives to be used from different manufacturers. The result is that some capacity may be lost due to the difference in actual capacities between different manufacturers even though the nominal capacity is the same.
NOTE: If the disks that are being used to form the RAID have different capacities, the RAID will be created using the smallest disk capacity of the different disks. Additional capacity on larger disks will be lost.
RAID Expansion
The Raidtec FS3102 system supports online expansion of the RAID. This expansion is accomplished in two possible ways, by row or by column. The controller decides what the best way of expanding the RAID is. The user does not have the ability to choose the expansion method.
Expansion By Row
The RAID will be expanded by row if possible. To expand by row, the number of disks that are being added to the RAID must be the same number that are in the RAID that is being expanded. The RAID will be expanded by adding an additional row of disks to the RAID. The number of columns in the RAID will remain the same. If the original RAID was level 5, the controller will have to initialize parity for the new row.
NOTE: If the disks that are being used to form the additional row have different capacities, the row will be expanded using the smallest disk capacity of the disks being added. Additional capacity on larger disks will be lost. The capacity of the disks in the new row can be different from the first row of disks.
Expansion By Column
Raidtec FS3102 Hardware Installation Guide | Version 1.0 | 28 |