Sx Spec

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DAC960SX Disk Array Controller • • • • • • • • • • Active/Active Operation Automatic Fail Over and Fail Back Wide Ultra SCSI to Disk and Host Simplex Operation capable High Performance Cache Up to 256 MB of Cache Memory Automatic Drive Sparing RAID 0, 1, 0+1, 3, 5 and JBOD Battery Backed Up Cache Memory Fully Mirrored Write Buffer • Stripe Depths of 8 KB to 64 KB • Flexible configurations: • 1 Host and 2 drive channels • 1 Host and 5 drive channels • 2 Host and 4 drive channels • Configuration through serial or host SCSI ports • Up to 70 drive support* • MORE Mylex On-line RAID Expansion* • COD Configuration On Disk The DAC960SX provides all the RAID disk array controller functions to build a fault tolerant storage system with fully transparent controller failover. Coupled with other fault tolerant system components, such as redundant fans and power supplies, the SX provides disk array features and performance for demanding server - I/O intensive applications. The SX is easily integrated into an existing 5¼” drive bay using the SXI enclosure, or becomes part of a custom enclosure with enhanced features, such as hot-swap, when used in accordance with the DAC960SX OEM Manual. SCSI bus support includes FAST and Ultra for both 8 and 16 bit devices. A large cache memory reduces read latency using Mylex advanced read ahead algorithms. Write data is stored in mirrored buffers, one on each controller, to protect data in the event of a controller failure. The battery protected write buffer survives power interruptions of up to 72 hours (depending on cache memory size). Operating in duplex mode, two SX controllers are active and provide RAID storage connectivity with up to twice the performance of a single controller. Should one controller fail, the surviving controller transparently takes over I/O processing for the failed controller. The SX can also be used in simplex mode for entry-level arrays, and can later . be seamlessly upgraded to duplex. And, with configuration information stored on the disk drives, a replacement controller comes on-line automatically. * Feature enhancement in version 3.5 firmware, due in Q3 ‘97 Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 1 of 12 rev 0.91 4/1/97 Functional Description The DAC960SX is a full featured disk array controller that can be integrated into a disk array subsystem or used in the Mylex DAC960SXI 5¼” enclosure. The SX consist of four components; the motherboard, the optional daughterboard, the BBU (Battery Backup Unit), and memory SIMMs. The motherboard provides 1 host and 2 Ultra SCSI disk channels. The daughterboard adds three more Ultra SCSI channels that can be used as 1 host and 2 disk connections, or as 3 disk channels. All SCSI connections are 16 bit Ultra (Fast-20). A 202 pin card edge connector on the motherboard and on the daughterboard connects either to a backplane connector for OEM integration, or to one of the available distribution boards when cabled connections are desired. The controller features a high performance memory system for staging data for RAID operations and caching data. Up to 8 System Drives can be independently configured as RAID levels 0, 1, 0+1, 3, or 5, and with Write Back or Write Through caching. Spare drives can also be configured and are automatically used when there is a drive failure. The cache memory can range from 8 MB to 256 MB using two 72 pin DRAM SIMMs. The Battery Backup Unit maintains the contents of the cache memory during a power failure for periods up to 72 hours for a 16 MB memory, and is designed to work with standard Fast Page, Low Power, or Self Refreshing DRAM. Configuration and management of the SX is done through the host SCSI channel(s) using the Mylex DACSX utility, through the RS-232 serial VT100 port, or through the LCD/keypad interface. Specifications for configuration protocols are available to aid in the development of customer proprietary configuration software or LCD/keypad interface. The DAC960SX is based on an embedded 32bit RISC processor with an interleaved memory system capable of data transfer speeds up to 132 MB/sec. Each SCSI channel is controlled by a SCSI I/O Processor to distribute the processing load. On board FLASH ROM can be updated in the field. Operated as redundant controllers, the SX provides controller fault protection with transparent automatic failover and failback. When a controller fails, the surviving controller takes over the SCSI ID of the failed controller. When the failed controller is replaced, the surviving controller returns the host SCSI ID to the replacement, once it has booted and received the system configuration using COD (Configuration On Disk). Cached write data is mirrored onto both controllers for System Drives with the Write Back feature enabled. The incomplete writes of a failed controller are always completed by the surviving controller. Under normal operation, a redundant pair of controllers are Active/Active, that is, both will process I/O requests from the host system, providing up to twice the performance of a simplex configuration. When a controller fails, the system performance is equivalent to a simplex system. System drives configured as RAID 1, 0+1, 3, or 5 are protected against a single disk drive failure. Should a drive fail, the affected System Drive is marked ‘critical’ and the SX will continue processing I/O by reconstructing the data from the remaining disk drives. When the failed drive is replaced (or if the system had a spare drive), the SX will rebuild the redundancy information onto this drive and resume normal operation. With the release of Version 3.5 of the controller firmware two new features will be available. The maximum number of disk drives controlled by the DAC960SX is expanded from 30 to 70. And Mylex On-line RAID Expansion (MORE) allows a System Drive to be expanded while the SX controller(s) process I/O. This allows system administrators to easily expand capacity transparently and when needed. These firmware enhancements can be added by downloading the new firmware into the controller reprogrammable ROM when available Spring 1997. Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 2 of 12 rev 0.91 4/1/97 Clock PLL i960CF CPU Clocks _____ Clock Disk Channel 0 BBU XMC ASIC Main Memory 2 SIMMs 8MB - 256MB SIOP 0 Disk Channel 1 SIOP 1 Host Channel 0 SIOP SIOP 8 Memory Bus Interface Local Bus Slow Bus Interface Dual UART NVRAM 16KB Flash EPROM 512KB Master / Slave Handshake 8-Bit Output Port Box Monitor I/Ps PIA Serial Port “A” Serial Port “B” Board Control LCD Display & Keyboard Interf Channel Fault Management DAC96 Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 3 of 12 rev 0.91 4/1/97 Active/Active, Fail Over and Fail Back Operation The DAC960SX is designed to operate in a dual controller fault tolerant environment as well as single controller systems. When configured as a redundant pair, both controllers have access to the same disk drives and both process host I/O. A communication signal between the controllers keeps each informed that the other controller is operating normally. If the communication signal is interrupted, the controller that detects the interruption asserts a reset signal to the other controller and starts processing I/O for both controllers. This “Fail Over” is transparent to the host computer because the surviving controller can respond to multiple target ID’s on the host SCSI bus. Interruption of the communication signal can result from a controller being removed from the system or the controller experiencing a fault causing it to intentionally “lock-up” when some abnormal operation occurs. This feature prevents a controller with suspect hardware from corrupting data. When the failed controller is replaced, the surviving controller will release the reset signal and allow it to start. Once running, the new controller establishes the communication signal and determines the system configuration. The surviving controller then initiates a “Fail Back” sequence to hand over the I/O processing to the new controller. The system is then back to Active/Active operation. Cache and Write Back and Write Through Features Read requests result in additional data being read from the disk drives using advanced Mylex proprietary read ahead algorithms. Data is stored in the on-board memory and will replace data that has not been accessed recently. Read latency is significantly reduced when a read request is serviced directly out of cache. Read after write is also very fast, as write data is held in cache memory while waiting to be flushed to disk. Write caching can be either Write Back or Write Through. When Write Back is selected, data is stored in cache and the host is notified that the write transaction is complete without waiting for the data to be written to disk. In an Active/Active system, the write data is copied to a buffer in the other controller before the host is acknowledged so the write data is mirrored. Write Back data is flushed to disk within 5 seconds. Write Through caching requires that data be written onto the disk(s) before the host receives an acknowledgment that the transaction is complete. Battery Backup Unit (BBU) To protect write data for System Drives configured as Write Back, the memory is maintained by a BBU when power to the controller is interrupted. As soon as the power supply begins to drop below the nominal value, a circuit on the SX puts the controller into a reset state to prevent unstable operation and switches the power for the memory to the BBU supply. The BBU also provides the signals to refresh the DRAM SIMM, and supports standard Fast Page DRAM, Low Power, and Self Refresh memory types. A fully charged BBU has capacity to support 16 MB Self Refresh memory for more than 72 hours. The BBU has a connector for an external battery supply to extend the memory hold up time. The BBU is available with or without batteries. Recovery From Failed Disk Drives When RAID levels 1, 0+1, 3, or 5 are selected, redundant information is stored along with data on the disk drives to allow recovery when a disk drive fails. Host I/O continues normally after drive failure, and data from the failed drive is recreated. When the failed drive is replaced the data for that drive is automatically recreated and stored on the drive. Spare drive(s) can be added to the system so that a failed drive is automatically replaced. When the failed drive is replaced, the replacement drive becomes the spare. All of this takes place without interrupting host I/O operations, although there may be some degradation in performance until the failed drive is replaced or the spare drive is brought on-line. Priority of data reconstruction can be selected to trade off performance against reconstruct time. Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 4 of 12 rev 0.91 4/1/97 Performance Tuning Up to 8 System Drives can be configured, each with a different RAID level and write caching scheme. This allows tuning for different system performance requirements. Write Back caching can significantly boost write performance. With a selection between RAID levels 0, 1, 0+1, 3, and 5, an appropriate level of performance and redundancy can be selected. Stripe depth, the amount of data placed on a drive before data is diverted to the next drive, can be set to match the transaction size or to force multiple disks to be used for each transaction. Cluster Support The DAC960SX allows simultaneous access by multiple hosts to the data in the disk array. With transparent Fail Over and Fail Back, the SX allows the topologies shown below. With a single host SCSI bus topology, the system provides fault tolerant operation for failed servers, SX controllers, and disks. LAN Server A Server B SCSI Host Bus DAC960SX ID 0 DAC960SX ID 1 ... ... SCSI Disk Busses ... Single Host Bus Topology LAN Server A Server B SCSI Host Bus B SCSI Host Bus A ID0 ID0 DAC960SX ID1 ID1 DAC960SX ... ... SCSI Disk Busses ... Two Host Bus Topology Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 5 of 12 rev 0.91 4/1/97 Using the DAC960SX dual host option, a two host bus topology is possible, extending protection to the connection between the server and the SX controllers. In this configuration, a cable or host bus adapter failure on one server cannot affect the other server’s ability to access the controller. Distributing the RAID groups across the disk SCSI busses (as opposed to down a single SCSI bus) provides additional protection against failed disk interconnections. Flexible Configurations There are variety of configurations to accommodate larger and smaller systems and different levels of fault tolerance. The following diagram shows some of the combinations possible with the available SX components. Two to 5 SCSI disk channels and 1 or 2 host SCSI channels in either simplex (one controller) or duplex (two controllers operating Active/Active and redundant). Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 6 of 12 rev 0.91 4/1/97 DAC960SX <<<>>> DACSX-2-xM-MYL 1 host/2 disk channels with BBU and x MB installed. DAC960SX ... ... DAC960SX ... DAC960SX Daughter board <<<>>> 2 x DACSX-5-xM-MYL 1 host/5 disk channels with BBU and x MB installed. DAC960SX Daughter board DAC960SX DAC960SX Daughter board ............ ... ............ ... Daughter board ... <<<>>> 2 x DACSX-5-xM-MYL 2 host/4 disk channels with BBU and x MB installed. ... ... ... ... Copyright Mylex Corporation, 1997 DAC960SX Daughter board DAC960SX Daughter board ............ ... DAC960SX Product Specification page 7 of 12 rev 0.91 4/1/97 Integration The DAC960SX makes all system connections through a 202 pin card edge connector and is designed to fit into the space of a half height 5¼” disk drive. While there are some jumpers on the SX, all configuration options, such as host channel ID, are available on the 202 pin connector for automatic configuration when inserted into a system. When used as a duplex controller for Active/Active operation, some signals must be connected between the controllers. Also, systems designed for hot-replacement of components, including the controllers, will need to follow the recommendations in the DAC960SX OEM Manual. Also described in the manual is the interface for a 4 line/20 character LCD display and keypad that can be used for configuration and management. The following table is an abbreviated signal list for 202 pin card edge connector (bussed signals are not all shown). Refer to the DAC960SX OEM Manual for full details. Pin Name Function S0 I/O: SCSI Disk Channel 0 (16b) S0TPW OUT: SCSI Disk Channel 0 Term Power S0FLT0-9* I/O: SCSI Disk Channel 0 Drive 0 - 6 Fault LED Drivers S1 I/O: SCSI Disk Channel 1 (16b) S1TPW OUT: SCSI Disk Channel 1 Term Power S1FLT0-9* I/O: SCSI Disk Channel 1 Drive 0 - 6 Fault LED Drivers S8 S8DIR I/O: SCSI Host Channel 0 (16b) OUT: SCSI Host Channel 0 Data Dir Control S8TPW S8DIFSNS OUT: SCSI Host Channel 0 Term Power IN: SCSI Host Channel 0 Differential Sense Signal JP0 JP1 JP2 IN: Host SCSI differential control IN: Serial Port A protocol select IN: Serial Port A auto-baud control FAN0 - 2* IN: Fan status PSFLT0 - 2* IN: Power supply status TEMP* IN: Temperature status MSSEL* RSTCOM* CHKMSTR IN: Master select; Slot ID I/O: Controller reset OUT: Master mode indicator HID0 - 3* IN: SCSI Host Channel 0 Base ID Select HLED* SLED* CDIRTY* OUT: Host channel active LED OUT: Disk channel active LED OUT: Cache dirty LED Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 8 of 12 rev 0.91 4/1/97 Pin Name Function ALARM* ALRES* OUT: Alarm driver IN: Alarm reset over-ride TXDA RXDA RTSA DTRA DCDA DSRA CTSA OUT: Serial Channel A Transmit Data IN: Serial Channel A Receive Data OUT: Serial Channel A Request To Send OUT: Serial Channel A Data Terminal Ready IN: Serial Channel A Carrier Detect IN: Serial Channel A Data Set Ready IN: Serial Channel A Clear To Send TXDB RXDB OUT: Serial Channel B Transmit Data IN: Serial Channel B Receive Data +12V +12 volt standby +5V GND The SX has the following dimensions: • • • • • • Length Width Height (Component side) Height (Bottom side) Height with Battery Board Overall height with daughterboard 8.000” 5.500” 0.600” 0.100” 1.200” 1.612” The following two diagrams show the mechanical outline for the SX with BBU and daughterboard. Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 9 of 12 rev 0.91 4/1/97 5.500 0.250 0.250 0.250 0.250 Top (Component) Side 8.000 0.700 0.700 PIN 1 0.310 2.123 0.115 2.476 0.074 0.523 0.074 0.115 DAC960SX Main Board Profile Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 10 of 12 rev 0.91 4/1/97 0.600 LCD Connector 0.550 Memory SIMMs and Heat Sink Optional Battery Board with Batteries 1.200 0.250 Optional Daughterboard 0.100 0.063 nominal 1.612 DAC960SX Main Board Height Profile Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 11 of 12 rev 0.91 4/1/97 Ordering Information The standard configuration for the DAC960SX includes the BBU and Self Refresh DRAM SIMMs. Standard models are: DACSX-2-16M-MYL DACSX-2-32M-MYL DACSX-2-64M-MYL DACSX-5-16M-MYL DACSX-5-32M-MYL DACSX-5-64M-MYL 1 host/2 disk channels with BBU and 16 MB Self Refresh SIMMs. 1 host/2 disk channels with BBU and 32 MB Self Refresh SIMMs. 1 host/2 disk channels with BBU and 64 MB Self Refresh SIMMs. 1 or 2 host/5 or 4 disk channels with BBU and 16 MB Self Refresh SIMMs. 1 or 2 host/5 or 4 disk channels with BBU and 32 MB Self Refresh SIMMs. 1 or 2 host/5 or 4 disk channels with BBU and 64 MB Self Refresh SIMMs. Custom configurations are also available, such as units without BBUs or BBUs without batteries, standard Fast Page memory or larger memory configurations. In addition, the DAC960SXI enclosure provides a convenient way to put a DAC960SX controller into any 5¼” drive bay. Standard models are: DACSXI-2W16M-MYL 1 host/2 disk channels with BBU and 16 MB Self Refresh SIMMs. DACSXI-2W32M-MYL 1 host/2 disk channels with BBU and 32 MB Self Refresh SIMMs. DACSXI-2W64M-MYL 1 host/2 disk channels with BBU and 64 MB Self Refresh SIMMs. DACSXI-5W16M-MYL 1 or 2 host/5 or 4 disk channels with BBU and 16 MB Self Refresh SIMMs. DACSXI-5W32M-MYL 1 or 2 host/5 or 4 disk channels with BBU and 32 MB Self Refresh SIMMs. DACSXI-5W64M-MYL 1 or 2 host/5 or 4 disk channels with BBU and 64 MB Self Refresh SIMMs. DACSXI-4D16M-MYL 1 or 2 host/5 or 4 disk channels with BBU and 16 MB Self Refresh SIMMs, with Differential host channels. DACSXI-4D32M-MYL 1 or 2 host/5 or 4 disk channels with BBU and 32 MB Self Refresh SIMMs, with Differential host channels. DACSXI-4D64M-MYL 1 or 2 host/5 or 4 disk channels with BBU and 64 MB Self Refresh SIMMs, with Differential host channels. Copyright Mylex Corporation, 1997 DAC960SX Product Specification page 12 of 12 rev 0.91 4/1/97