General information

This section provides general information about the IBM® SAS RAID controllers for Linux®.

The controllers have the following features:

• PCI-X 266 system interface or PCI Express™ (PCIe) system interface.
• Physical link (phy) speed of 3 Gb per second Serial Attached SCSI(SAS) supporting transfer rates of 300 MB per second.
• Supports SAS devices and non-disk Serial Advanced Technology Attachment (SATA) devices.
• Optimized for SAS disk configurations which utilize dual paths thru dual expanders for redundancy and reliability.
• Controller managed path redundancy and path switching for multiported SAS devices.
• Embedded PowerPC® RISC processor, hardware XOR DMA engine, and hardware Finite Field Multiplier (FFM) DMA Engine (for Redundant Array of Independent Disks (RAID) 6).
• Some adapters support nonvolatile write cache.
• Support for RAID 0, 5, 6, and 10 disk arrays.
• Supports attachment of other devices such as non-RAID disks, tape, and optical devices.
• RAID disk arrays and non-RAID devices supported as a bootable device.
• Advanced RAID features:
  • Hot spares for RAID 5, 6, and 10 disk arrays
  • Supports up to 18 member disks in each RAID array
  • Ability to increase the capacity of an existing RAID 5 or 6 disk array by adding disks
  • Background parity checking
  • Background data scrubbing
  • Disks formatted to 528 bytes per sector, providing cyclical redundancy checking (CRC) and logically bad block checking
  • Optimized hardware for RAID 5 and 6 sequential write workloads
  • Optimized skip read/write disk support for transaction workloads
• Supports a maximum of 64 advanced function disks with a total device support maximum of 255 (the number of all physical SAS and SATA devices plus the number of logical RAID disk arrays must be less than 255 per controller).