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Date: Wed, 20 Nov 1996 19:41:24 GMT
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<HTML><HEAD><TITLE>The Tower of Pizzas</TITLE><!-- This is a comment --><!-- if you have problems, mail webmaster@cs.umd.edu --></HEAD><BODY BACKGROUND="brick.jpg" BGCOLOR="#ffffff" TEXT="#000000" LINK="#008000" VLINK="#FF0080" ALINK="#FFFFFF"><H1>The Tower of Pizzas </H1><hr><H2>Researchers</H2><UL><LI><b><!WA0><a href="http://www.cs.umd.edu/users/nick/">Dr. Nick Roussopoulos</a></b><i>, Principal Investigator</i><LI><b><!WA1><a href="http://www.cs.umd.edu/users/mdtanx/">Michael Tan</a></b><i>, Graduate Student</i><LI><b>Stephen Kelley</a></b><i>, Research Associate</i></UL><H2>Description</H2>We have constructed the Tower of Pizzas (TOPs), a multi-user, stripedstorage system. The main goals of TOPs are 1) to provide access todata striped across workstations, 2) to exploit caching andprefetching at the client and server, 3) to implement the system at ahigh-level for portability, 4) to explore data layout.<p> The system is implemented in software on top of general UNIX Thisallows workstations of heterogeneous flavors of UNIX to work togetheras clients and servers. Server workstations run a single serverprocess, and clients talk to remote servers through a local serverprocess or through a linked library. The local and remote serverprocess are identical, which allows TOPS to be run as a peer-to-peercollection of workstations (rather than just a partitioned set ofclients and servers). The local and remote server processes providebuffer management, striping (configurable per file) over the network,and disk services (including asynchronous read/write). Local clientsaccess buffers of the local server through shared memory.Asynchronous read/write disk I/O is provided through the serverthreads and aio calls. File meta-data is centralized at a serverprocess accessed only on open() or close().<p>TOPs has been implemented over the past year and we have now run it ona variety of hardware clusters: SPARCs and an Alpha connected byEthernet, and our 16-node SP2 (using TCP over the high-speed switch).On the SP2 we can demonstrate linear scalability of global throughputas servers and clients are added.<p>At this point we are now starting more detailed investigation incaching and prefetching strategies. We are also examining new dataplacement techniques.<p><H2>Performance</H2>In the three tests below, 1 to 10 clients are run using 1 to 8 servers(srvs). The y-axis gives the total system throughput (the sum of thethroughput delivered to each client). Note that the filesystem anddisks used for these tests can transfer data at 3.5 MB/s forsequential reads and about 1 MB/s for random reads. <dl> <dt> <b>Reading cached server data.</b> In this test, clientsread from a small file (8 MB/server). The file is completely cachedat the server, so no disk I/O (other than the initial load from disk)is incurred. The test shows the overhead of TOPs and indicates themaximum performance possible on this platform.<p> <dd><!WA2><IMG ALIGN=top SRC="http://www.cs.umd.edu/~mdtanx/readsmall.gif"> <p> <p><dt> <b>Group sequential read with a prefetch/ordering strategy.</b>In this test, each client read sequentially through a large file.The portions of the file read by each client was disjoint from oneanother. We used a prefetching strategy to maintain sequential accessto the disk (the requests from the clients were not synchronized).<p><dd><!WA3><IMG ALIGN=top SRC="http://www.cs.umd.edu/~mdtanx/readpref.gif"><p><p><dt> <b>Reading from large disk files.</b> In these tests, each clientcontinually requested a small contiguous portion of the data file.Each request started at some random point in the file. The data filewas relatively large (160 MB per server, and could not be entirelycached.<p><dd><!WA4><IMG ALIGN=top SRC="http://www.cs.umd.edu/~mdtanx/readlarge.gif"><p><p></dl><H2>Publications</H2>A <!WA5><a href="http://www.cs.umd.edu/users/mdtanx/tops.ps.Z">technical report</a> (submitted for publication) and brief <!WA6><a href="http://www.cs.umd.edu/users/mdtanx/gc2.ps">set of slides about TOPs</a> is available. <HR><I>Last updated on Fri September 21 12:01 1995</I><HR></BODY></HTML>⌨️ 快捷键说明
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