Frequently Asked Questions August s840z SAS SSD Enterprise-Class Solid-State Device. Frequently Asked Questions

Transcription

1 August 2013 s840z SAS SSD Enterprise-Class Solid-State Device Frequently Asked Questions

2 Frequently Asked Questions Q: In what applications do HGST s840z SAS SSDs benefit enterprise customers? A: s840z SAS SSD is purpose-built for the ZIL workload in a ZFS Hybrid Storage environment. All enterprise customers that utilize ZFS based storage solutions from companies like Nexenta, will see a dramatic improvement in storage system performance when using s840z. Q: Where does the s840z SAS SSD fit in a typical ZFS Hybrid Storage environment? A: ZFS is a robust, scalable file system with features not found in other file systems available today. A typical ZFS Hybrid Storage environment consists of: Adaptive Replacement Cache (ARC): The ARC lives in DRAM. Level-two ARC (L2ARC): The L2ARC lives in SSDs. (Read cache) ZFS Intent Log (ZIL): The ZIL is used to handle synchronous writes write operations that are required by protocol (e.g., NFS, SMB/CIFS) to be stored in a non-volatile location on the storage device before they can be acknowledged to ensure data stability Hard Disk Drives (HDD): provide lower-performance, higher- density, low-cost storage capacity s840z SAS SSDs are the ideal fit for ZIL. As databases usually require transactions to be on stable storage devices before continuing, reducing the latency of synchronous writes directly impacts the storage solution s performance. ZFS can do this by placing the ZIL on a low write, latency-optimized SSD. All writes (whether synchronous or asynchronous) are written into the ARC in DRAM, and synchronous writes are also written to the ZIL before being acknowledged. Q: How does a business know when to use HGST s840z SAS SSD vs. any other SSD? A: s840z comes standard with dual ports necessary for High Availability (HA) as well as a, higher number of storage chassis and subsystems shipping with 2.5 drive slots. s840z is built to fit standard 2.5 ZIL deployments. Q: Do HGST SAS SSDs have a near-zero unrecoverable error rate? A: Shrinking flash chip geometries enable greater capacities and lower the cost of SSDs, but if not managed correctly, higher densities can increase the rate of media errors and reduce reliability. HGST s Secure Array of Flash Elements (SAFE) Technology delivers a near-zero unrecoverable error rate. Advanced redundancy technology developed by HGST enables the SSD to recover from almost any flash media failure scenario. 2

3 Q: How does HGST provide protection for data? A: Mission-critical enterprise and data center applications cannot afford data loss due to unscheduled power outages or silent data corruption of storage media. Enterprise-class SSDs from HGST provide built-in power backup capacitors to protect against electrical power failures, plus internal data-path protection with built-in error correction codes (ECC), cyclic redundancy checks (CRC) and parity-based error detection and correction to maximize data integrity. Q: Why choose s840z SAS SSDs over competitive solutions? A: HGST s total value proposition is unbeatable when it comes to expertise in: Low write latency Managing ZIL workloads (purpose-built) High DWPD (860 Drive Writes Per Day for 5Years) >2x better steady-state random performance compared to competition under real-world conditions Steady-state performance Enterprise-level endurance Custom in-house-designed controller technology, enabling advanced performance and capability Manufacturing in-house (by HGST, not contract manufactured) Full HGST warranty protection and support Q: Do HGST s840z SAS SSDs support compression and data de-duplication? A: s840z SAS SSDs do not utilize compression or data de-duplication. Some competitors use compression and data de-duplication in order to claim increased performance and/or endurance. If your enterprise data is incompressible, you lose the stated performance of the drive, and your endurance is dramatically reduced. HGST is focused on true mission-critical enterprise data center environments, and thus does not implement these methods when it is expected that many missioncritical applications will not have compressible data. Q: What capacities are offered by the s840z ZIL SAS SSD? A: HGST s s840z SAS SSD offers 16GB of capacity* in a 2.5-inch standard form factor. Q: Do s840z SAS SSDs come in a 3.5-inch form factor? A: No. HGST s840z SAS SSDs are currently offered in a 2.5-inch form factor. HGST offers ZeusRAM in a 3.5 form factor. Q: What architecture is used in the s840z? A: The s840z ASIC controller was designed in-house by HGST in continuation of our 20-year history of creating industry-leading solid-state drive products. 3

4 Q: How long will the s840z last, and what restrictions exist? A: s840z carries a 5-year warranty and allows for about 860 full-capacity writes per drive per day. Q: Does the s840z protect against unexpected power-down data loss? A: HGST s PowerSafe Technology internally supports capacitor backup power. In the event of host power loss or brownout, HGST utilizes a sophisticated algorithm to ensure that data loss does not occur while detecting and holding up device power to enable the SSD to write host data and shut down the drive cleanly. *As used for storage capacity, one megabyte (MB) = one million bytes, one gigabyte (GB) = one billion bytes, and one terabyte (TB) = one trillion bytes. Available capacity will vary depending on operating environment and formatting. Q: How does error correction (ECC) work in s840z SAS SSDs? A: HGST embeds multiple engines within the controller to allow concurrent operations to occur without slowdowns in the event that an ECC correction is required. HGST s SAFE Technology adds another level of ECC protection. Q: How do you measure SSD endurance and reliability? A: SSD endurance is defined as the total amount of random host data that can be written within the life of the drive. Factors that affect SSD endurance include NAND technology, write workloads, reserve capacity and SSD controller firmware. HGST SSDs use advanced error detection and correction, highly efficient firmware algorithms engineered by HGST to provide data integrity, and CellCare Technology to extend the endurance of flash media and maximize product life. Q: What does SMART stand for? A: SMART, an acronym for Self-Monitoring, Analysis and Reporting Technology, was originally developed for ATA devices. The specification has been adapted so that SCSI devices can support SMART capabilities. As this specification was originally conceived for drives using platter technology, not all of the reporting features apply to flash-based media drives. An HGST SAS SSD incorporates a very comprehensive set of attributes and data in its SMART implementation to monitor the health and operation of the SSD in a working environment. Q: Does the s840z support SMART? A:The s840z supports SMART commands and attributes to track internal events and report problems to the host in an effort to predict an impending failure. 4

5 Q: Is the s840z PnP compatible, or does it need additional drivers? A: The s840z is Plug-and-Play (PnP) compatible; no additional device drivers are required to install the drive. The SSD is recognized by PnP-compatible operating systems and PnP-aware BIOS. Q: What is a good measure of the lifetime of the flash media used in the s840z? A: Using SMART reporting methods, the SSDs will offer an attribute giving the life remaining ( Lifetime Remaining Percentage ) in the endurance of the SSD. A new, (unused) s840z SAS SSD will display a SMART value in the Lifetime Remaining Percentage value of 100, while an SSD that has reached its write endurance limit will display a Lifetime Remaining Percentage value of 1. Q: How can I measure the lifetime remaining percentage of s840z SAS SSDs? A: The HGST Device Manager (SDM) tool kit is a free software application available for download from the HGST website. This tool can be used to query a drive for its SMART data, including the lifetime remaining percentage. This is made possible by HGST s implementation of the SMART attribute (E9) (Lifetime Remaining Percentage). 5

6 2013 HGST, Inc., 3403 Yerba Buena Road, San Jose, CA USA. Produced in the United States 08/13. All rights reserved. Other trademarks are the property of their respective companies. HGST trademarks are intended and authorized for use only in countries and jurisdictions in which HGST has obtained the rights to use, market and advertise the brand. Contact HGST for additional information. HGST shall not be liable to third parties for unauthorized use of this document or unauthorized use of its trademarks. References in this publication to HGST s products, programs, or services do not imply that HGST intends to make these available in all countries in which it operates. Product specifications provided are sample specifications and do not constitute a warranty. Information is true as of the date of publication and is subject to change. Actual specifications for unique part numbers may vary. Please visit the Support section of our website, for additional information on product specifications. Photographs may show design models. One GB is equal to one billion bytes and one TB equals 1,000 GB (one trillion bytes) when referring to hard drive capacity. Accessible capacity will vary from the stated capacity due to formatting and partitioning of the hard drive, the computer s operating system, and other factors. FQ003-EN-US