Download - Plasmon

How Diamond worksStorage strategiesSmall directoriesAvoid having very large directories on optical disks, since this can reduce systemperformance when opening files. As a general rule of thumb, more than 512 entries ina directory is large.Large filesThe key performance characteristics of optical disk drives are that disk seeks are slowerthan reads and writes (writing is typically slower than reading). The extent depends onthe technologies used in a specific drive.The result is that system throughput increases as average file size increases. Averagefile size should be at least 30KB to obtain good performance. Optimal performance isachieved at a file size of around 3 to 10MB, depending on the application.Finally, the time taken to import a disk into the library is proportional to the numberof files on the disk. If the average file size is low, there will be more files on the diskand import will take longer.Diamond will work with small files, but works more efficiently if you can increase youraverage file size when you design your information system. This rule applies to mostoptical storage implementations, especially those adhering to ISO-13346 or OSTA UDF.Note: For small files on DVD, the ‘Archive’ file system gives considerableperformance enhancement over most file systems. The Archive file systemis a WORM file system.Diamond supports virtual directories (also known as deep mounts), providing anadditional method of adding more available space at specific parts of the librarydirectory tree.Keeping related data togetherDisk exchanges may be kept to a minimum by keeping associated files on the samedisk surface (this is equivalent to keeping files in the same primary subdirectory treestructure) and precludes the use of volume groups. When setting up a storage system,performance will be improved by partitioning the data in this way.Diamond Administrator’s Guide 17