Sierra T244

Serial Attached SCSI (SAS) is the next-generation replacement of SCSI Ultra320. SAS is a serialized protocol. The serial interface offers several benefits over the existing SCSI parallel bus; allowing for high availability, complex storage topologies, and a lower cost structure.

High Availability: As with SATA, Serial Attached SCSI is a high-speed, point-to-point technology initially designed to operate at speeds up to 6Gb/sec. System designers have found that point-to-point serial connections are inherently more reliable than shared bandwidth parallel connections. As a result, point-to-point serial connections have become the preferred method for implementing high-availability systems. SAS based disk drives are dual ported, taking advantage of this feature. This is a key requirement of high-availability SANs that call for redundant paths to all devices in the system.

Complex Storage Environments: SAS storage environments usually consist of a mixture of disk drives, host bus adapters and expanders. SAS allows for addressing of over 16,000 devices. SAS Expanders are routing devices that forward service requests between the source and destination devices. Expanders can be attached to other expanders, disk drives, and other hosts. An important characteristic of Expanders is their ability to aggregate bandwidth by combining multiple physical links into a "Wide" port. These wide ports can function as intelligent switches and can independently send commands across one physical path with data being returned over a different physical path. This increases the complexity of SAS test and debug because it requires users to monitor multiple links concurrently to record all DWORDs associated with a single SCSI transaction. The usage of expanders also allows for usage of a storage concept called Zoning. Zoning allows administrators to restrict access to devices by other devices. Applications of this include separating storage systems within a company by department.

Lower Cost Structure: Serial Attached SCSI also contains support for SATA drives in its storage environments. This allows support for both enterprise-class performance offered by SAS and low cost storage with SATA drives in the same system. Since the cost of the SAS infrastructure is expected to be comparable to SATA, it is likely that SAS will be the preferred interface. Since both SAS and SATA drives can be used in this environment, it will simplify and standardize the storage infrastructure, allowing for the ability to choose which drive will best fit individual storage needs.

SAS Test and Verification: LeCroy's protocol analysis tools are designed from the ground up to address these unique characteristics of SAS including wide-links and Serial ATA interoperability. Sierra’s analysis and design suites are developed specifically for use with the SAS and SATA protocols, and provide extensive protocol decoding, expert error analysis, and complete user support when decoding and viewing the recorded traffic. This extensive protocol support, combined with the different traffic views, advanced triggering, data filtering, traffic generation, and error injection capability, allows engineers to rapidly become familiar with SAS- and SATA-specific issues, and quickly understand new issues the first time they encounter them. Every engineer becomes a protocol expert with the support of Sierra’s detailed expert analysis.

Designed for the SAS 4.0 (24 Gb/s) standard, the Sierra T244 provides the most accurate capture, display and analysis of the next generation SAS protocol. Featuring the industry's highest-fidelity probe design, the Sierra T244 seamlessly locks on 24G signaling without distorting the dynamic link training sequence. For comprehensive testing and verification of components, backplanes and subsystems, the Sierra platform delivers true end-to-end visibility to help ensure SAS 4.0 performance and reliability.

The Sierra T244 features custom probe technology known as T.A.P.4™ (Transparent Acquisition Probing) which has been field-proven in Teledyne LeCroy's 32Gb/s Fibre Channel and PCIe 4.0 analyzer platforms. Leveraging this cutting-edge analog front-end, the T244 provides a robust analysis platform well suited for both silicon bring-up, as well as multi-vendor interoperability testing. The T.A.P.4 probe design sets the standard for accuracy by seamlessly capturing and analyzing the critical link initialization and speed negotiation sequence. Designed to operate transparently, the Sierra passes signals that are nearly identical to the original DUT signaling. This ensures the system-under-test behaves consistently while the Sierra records the 24 Gb/s link training coefficients without distorting the dynamic equalization process.

The Sierra chassis supports a convenient design for stacking or racking multiple units and still provide access to all data and control ports. Suitable for either bench-top or storage rack environments, the Sierra includes support for both USB 3.0 and Gigabit Ethernet host connections. Combining SuperSpeed upload with the convenience of USB plug-and-play connectivity can save hours of time over the life of the equipment. With the Ethernet port, the Sierra is fully addressable over the network with built-in utilities that display the current user, the IP Address and status. LEDs provide information on negotiated link speed, protocol error detection, link state, and whether OOB or data traffic is active. Memory configurations - from 32GB to 128GB -can address long recording times. A built-in port provides DC power for target devices to conveniently supply SSDs or HDDs with 12v or 5v power. The rear chassis also provides a sync-port capable of synchronizing trace captures from multiple analyzers.

Seamlessly integrated with Teledyne LeCroy's expert analysis software, the Sierra platform overcomes the struggles of legacy debug tools with a revamped graphical interface featuring easy to understand displays of protocol traffic. For viewing commands and frames in sequential order, the Spreadsheet View provides a traditional table format that can be customized to add any field in a separate column. The exchange level assembles frames and primitives into the logical SCSI command, data, and status transactions. This is critical for wide-port analysis where large gaps can occur between command and status. Full decoding of SMP Discovery request/response transactions makes it easy to troubleshoot scale-out storage applications.

Use the Frame Inspector to view primitives or drill-down on the 150-bit SPL packet structures including headers, payloads, scrambled and unscrambled symbols. The field view provides unprecedented decoding of higher layer protocol fields, including the full CDB as well as SCSI sense data and ASC qualifiers to streamline troubleshooting. All of the expert analysis views can be used simultaneously and are automatically synchronized / displayed within one application. Any combination of display and filter options can be configured as the default view making it faster to interpret captured traffic.

The Sierra provides hardware triggering to pinpoint protocol events of interest. Trigger events can be specified at the lowest levels including error conditions, bus states, primitives (, etc...) header fields (packet type, LBA, etc...), or SCSI parameters (CDB, Tag, etc...). The Advanced mode offers 24 sequential states, 4 independent timers, multiple counters, the ability to pre-filter at each state, and the ability to assign individual triggers to each port pair. Users can define sophisticated sequential event trigger scenarios including more complex events such as timing violations between state changes. From speed negotiation to protocol errors, virtually any logical SAS or SATA event can be defined as the trigger event.

The Sierra SAS verification system provides extensive traffic metrics and statistics to help locate and identify protocol issues. Traffic Summary reports are hyperlinked to the actual trace events. Navigation in the spreadsheet view is easy with Quick-Find. Click on any field and Quick-Find populates the search window with the highlighted string allowing easy navigation forward or backward. Add Boolean operators to find lower or higher values. The Quick Filter uses the same easy mechanism to hide redundant fields. Markers can be added, searched and displayed as tooltips.

With best-in-class features including T.A.P.4™ probing, 128GB recording memory, and SuperSpeed 3.0 data upload ports, the Sierra T244 system helps reduce time-to-market for storage developers.