2002 - cesnet

ecord size [kB] 256 512 1024 2048 4096 8192 16384iSCSI read 14473 25849 29185 30233 30254 31080 27051local read 21193 28629 31751 34477 35170 35888 37550NFS read 15291 23236 27448 29824 31973 34167 30208iSCSI write 8665 10975 11833 12344 11952 13141 11799local write 17269 17633 18981 20660 18642 23639 22230NFS write 10124 12203 12425 12742 16412 12390 16152Table 16.1: Reading and writing of individual alternatives [kBps]record size [kB] 256 512 1024 2048 4096 8192 16384iSCSI/L 68 % 90 % 92 % 88 % 86 % 87 % 72 %NFS/L 72 % 81 % 86 % 87 % 91 % 95 % 80 %iSCSI/L 50 % 62 % 62 % 60 % 64 % 56 % 53 %NFS/L 59 % 69 % 65 % 62 % 88 % 52 % 73 %Practical ExperienceTable 16.2: Network and local access comparisonThe development of the reference Intel implementation is either done with acompiler for the 64-bit platform, or only with historic SCSI devices. This resultsin a substantial restriction of the hard drive capacity to the int type value(hence, the drive capacity is limited to approx. 2 GB). We tried to modify thecode and replace the int type with the long type. However, the modification wasnot trivial. Exceeding the 2 GB limit caused the file system to crash. We decidedto continue in our testing with this restriction in mind and not to exceed thelimit.The code available at the UNH InterOperability Lab website was in fact notfunctional. After a connection is established, the operating system’s kernel onthe target side freezes.The implementation of Cisco cannot be used in collaboration with the Intel target– the initiator handles the drive geometry incorrectly. Although we managedto remove the previously mentioned effect by modifying the source code of theCisco initiator, the Intel target kept indicating errors within the communication.These errors were also caused by the fact that the Cisco initiator was sendingnon-standard requests (e.g., text strings about the software manufacturer), too.The results and practical experience we gained with the target and initiatorimplementation in Linux are summarized in the CESNET technical report No. 5/2002.High-speed National Research Network and its New Applications 2002177