PDF《Software RAID》

3 PERC S100 Implementation PERC S100 is a pure software solution, supported by Peak P55 express or ICH10r chipset. Option ROM for PERC S100 is integrated as part of system BIOS and an onboard SATA controller is used as channel to transfer the data to HDD. To make the PERC S100 functional, change the SATA setting to RAID mode in the system BIOS. The RAID becomes active when the OS has loaded the S100 driver software. SATA

2 hard disks, SSDs, and internal SATA tape device ( RD1000) are supported. Figure

2 shows the PERC S100 Option ROM and the menu options Figure 2. PERC S100 Option ROM

4 PERC S300 Implementation PERC S300 is a hybrid solution obtained by a firmware change for the LSI 1068E SAS controller. The advantage over PERC S100 is that SAS disks are supported in PERC S300. The conversion from LSI 1068E SAS controller to PERC S300 is done using the firmware upgrade (using DRMK bootable USB in DOS method). Figure

3 shows the PERC S300 Option ROM and Menu details Dell White Paper September,

2009 3 Software RAID Functionality on Dell Value Line Servers Figure 3. PERC S100 Option ROM

5 Features of Software RAID ? RAID 0,1,5, and

10 are supported ? Boot support for degraded virtual disks ? Cache support for physical and virtual disks ? Eight partial VDs can be configured under a single group ? Background initialization, check consistency, and rebuild ? Disk initialization is supported ? SMART feature monitors physical disks and attempts to detect and report potential or impending failures ? Support for CD /DVD ROMS Dell White Paper September,

2009 4 Software RAID Functionality on Dell Value Line Servers

6 SW RAID Integration with Dell Storage Management Software Figure 4. Communication Between Dell SW and PERC S100/S300 Figure

4 shows communication between Dell storage software and PERC S100/PERC S300 Software RAID Solutions, which are also called PERC S100 and PERC S300. They have been integrated into Dell Storage Management software that provides all the major functionalities performed on PERC S100 and PERC S300 after the OS is installed and the driver software has been loaded. Some of the main features that OMSS supports for software RAID solution are listed in the following sub-sections. 6.1 Device Discovery ? Controllers ? Backplane ? Physical Drives ? Virtual Drives Discovery is responsible for querying the SW RAID stack. 6.2 Consistency Check This can be initiated and cancelled by the user. OMSS exposes this as a re-synching task. 6.3 Create Virtual Disk 6.3.1 RAID Levels Supported VDs can be created by RAID levels 0, 1, 5, and 10. 6.3.2 Protocol and Media Type Mixing VDs may be created only when drives are all the same protocol and media type. S100 Controller S300 Controller SAS/SATA/ SSD SATA PCIe Gen2 Channel IBEX Peak C P55 Chipset/ICH10R Windows Server 2003/2008/OS API for the Driver DOT Hill Systems RAID Core Driver for the S300 and s100 Controllers System Memory Dell Storage Management Software Systems BIOS Receiving Commands at INT 13H Dell White Paper September,

2009 5 Software RAID Functionality on Dell Value Line Servers 6.3.3 Background Initialization The virtual disk create task invokes the background initialization automatically. Because there is no automatic restart of the background initialization by firmware as with PERC controllers, the automatic background initialization task runs and OMSS does not allow it to be cancelled. 6.3.4 Drive Rules ? A set of physical drives can host multiple Logical Drives (LDs). ? LDs can be of different RAID levels. ? LDs can use different physical drives with some/all/none overlap in their usage. For example, part of a drive creates a volume with the OS installed on it. The remaining space of this drive appears in the create VD wizards and may be used. 6.3.5 Stripe Size Stripe size cannot be specified by user at create VD time. The stripe size is automatically set by the SW RAID based on the total capacity and number of disks assigned to the virtual disk RAID levels. 6.3.6 Rebuild ? Affected logical drives track drive rebuilds. OMSS exposes this rebuilding and reports progress. ? A drive may participate in one or more simultaneous rebuilds. OMSS provides distinct alerts for the rebuilds, but the UIs display the lowest progress. 6.3.7 Reconfigure A VD cannot be transformed to another RAID level. The VD size may be grown if there is sufficient space in all of its physical drives or if an additional drive is added to the VD. 6.3.8 Spare Assignment ? A dedicated hotspare (DHS) may be assigned to a virtual disk only if the drive is of sufficient size and is of the same protocol and media type as of the virtual disk. Mixing is not supported. ? A global hotspare (GHS) may be assigned regardless of the number of VDs, their protocol, or their size, but GHS starts based on the availability of the size of the VD and the protocol. ? If sufficient free space is left, a drive may be a member of one or more VDs at the same time it functions as a DHS. 6.4 Event Management and Monitoring Software RAID events are mapped to OMSS alerts. SMART alerts are also supported in OMSS for PERC S100 and PERC S300. Events include informational, warning, and critical alerts.