---------------------------------------------------------------------------- The Florida SunFlash Sun Prestoserve SunFLASH Vol 31 #8 July 1991 ---------------------------------------------------------------------------- Sun Prestoserve is an NFS accelerator that improves the NFS responsiveness of SPARCserver 470 or SPARCserver 490 systems by up to 75 percent, and a SPARCserver 2 by up to 85 percent. By dramatically improving NFS write performance, Sun Prestoserve delivers significant improvement in disk throughput, so heavily loaded file servers can support more clients and offer better response times. Sun Prestoserve is available in both the SBus and VMEbus versions. The SBus version consists of a single width SBus card, and the VMEbus version consists of a single slot 9U VMEbus board. Both versions contain 1 Mbyte of nonvolatile cache memory, a UNIX device driver, and utility programs. The UNIX device driver operates as a pseudo disk driver in the SunOS kernel, intercepting NFS writes to disk and caching them in Sun Prestoserve nonvolatile memory. Installation, monitor, and control utilities support the administration and performance evaluation of Sun Prestoserve. Installation is easy, using an interactive installation script that requires about 20 minutes to complete. Once installed, Sun Prestoserve delivers transparent performance improvement without application modification or client rebooting. Product Highlights - Accelerates NFS performance by enhancing disk I/O throughput - Allows heavily loaded file servers to support additional clients by increasing NFS throughput by up to 80 percent on SPARCserver 470 and 490; and by up to 140 percent on SPARCserver 2 - Improves NFS server responsiveness by up to 75 percent on SPARCserver 470 and 490; and by up to 85 percent on SPARCserver 2 - Operates transparently - requires no client or application modifications - Maintains full NFS and UNIX filesystem semantics and compatibility - Includes single width SBus card with 1 Mbyte of nonvolatile CMOS static RAM (SBus version); or Includes 9U VMEbus board with 1 Mbyte of nonvolatile CMOS static RAM (VMEbus version) - Includes UNIX device driver and installation and utility programs - Complements Interphase NC400 Network CoProcessors to reduce NFS file server bottlenecks on VME based systems (SPARCserver 470 and 4 Performance Gains Sun Prestoserve accelerates NFS performance by caching NFS writes to nonvolatile memory and efficiently scheduling data transfers to physical disk. It reduces the number of writes to disk by eliminating redundant writes of file definition blocks (i-nodes and indirect blocks). For a 1 Mbyte data file, Sun Prestoserve can eliminate 65 percent of the required writes to disk. NFS writes and modifications occur at memory speeds rather than disk speeds because they are buffered into the Sun Prestoserve nonvolatile cache. Consequently, clients executing write commands get immediate response from the server. Because its cache is a nonvolatile storage medium, Sun Prestoserve does not sacrifice the data integrity advantage inherent in the NFS protocol. If the file server crashes, the data on the Sun Prestoserve cache are protected by battery backup. Data in the cache are flushed to disk storage asynchronously in 64Kbyte blocks. This allows Sun Prestoserve to improve the data transfer rates by optimizing the seek and rotational characteristics of the disks. Where Prestoserve Improves Performance? The greatest performance benefit occurs when a high percentage of NFS operations append or modify data. This percentage depends on the mix of client types and the types of applications those clients are running. Applications such as CASE, CAD, and electronic publishing require frequent saves to disk and therefore generate a high volume of NFS writes. A larger percentage of diskless clients also generates more NFS writes. Diskless clients rely exclusively on a networked file server for all information, so the volume of NFS calls per client is higher than with dataless or diskfull clients. PC clients using PC-NFS products also see substantial performance improvements from Sun Prestoserve. In VMEbus based SPARCservers, like SPARCserver 470 and SPARCserver 490 file servers, Sun Prestoserve works together with the NC400 Network CoProcessor from Interphase to improve the overall NFS performance. Sun Prestoserve reduces I/O bottlenecks, increasing NFS write speeds, while the NC400 reduces CPU and network bottlenecks by offloading network protocol processing. Sun Prestoserve does not significantly improve NFS performance in all file server applications. Sun Prestoserve is a cache that accelerates NFS writes to disk. File servers that are primarily read servers or lightly loaded servers do not benefit substantially from Sun Prestoserve. Hardware and Software Requirements Sun Prestoserve is supported on SPARCserver 2, SPARCserver 470 and SPARCserver 490. SunOS 4.1 or later is required for the VMEbus version, SunOS 4.1.1 or later is required for the SBus version. Sun Prestoserve requires one VMEbus slot in the SPARCserver 470 and 490 system; and one SBus slot in SPARCserver 2. Specifications SBus Version VMEbus Version Host interface SBus VMEbus Slots required 1 SBus slot One 9U slot Memory capacity 1 Mbyte 1 Mbyte Speed 150 ns 100 ns Type Static nonvolatile Static nonvolatile CMOS RAM CMOS RAM Temperature Operating 05C to 605C 05C to 605C Non operating -40 5C to 805C -40 5C to 805C Electrical power requirements +5V from VMEbus @ +5V from VMEbus @ 0.75A operating 1.8A operating 0.8A maximum 2.1A maximum 100mA standby 100mA standby Backup power Two redundant batteries Three redundant batteries Type +5V Lithium +5V Lithium Rating 750 mA/hr each, 3.5 V 1500 mA/hr each, 3.6 V Shelf life (batteries off) 5 years 8 years Operating life 2 to 3 years 2 to 3 years (without SBus or VMEbus power) ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ For information send mail to info-sunflash@sunvice.East.Sun.COM. Subscription requests should be sent to sunflash-request@sunvice.East.Sun.COM. Archives are on solar.nova.edu and paris.cs.miami.edu. All prices, availability, and other statements relating to Sun or third party products are valid in the U.S. only. Please contact your local Sales Representative for details of pricing and product availability in your region. Descriptions of, or references to products or publications within SunFlash does not imply an endorsement of that product or publication by Sun Microsystems. John McLaughlin, SunFlash editor, flash@sunvice.East.Sun.COM. (305) 776-7770.