Applied Biosystems 7900HT Fast Real-Time PCR System and SDS ...

Chapter 7Maintaining the InstrumentGeneral Computer MaintenanceMaintenanceScheduleThe computer connected to the 7900HT instrument requires regular maintenance toensure reliable operation of the Applied Biosystems 7900HT Fast Real-Time PCRSystem components. Applied Biosystems recommends the following tasks as part ofroutine maintenance of the computer system:Table 7-4Maintenance Schedule for the Instrument ComputerMaintenance TaskArchive or Remove Old SDS FilesDefragmenting the Hard DriveUpgrading the Operating System SoftwareUpgrading the SDS SoftwarePerformWeeklyMonthly or beforefragmentation reaches 10%When available/advisableWhen availableDeveloping a Data Management StrategyApplied Biosystems recommends developing a strategy for dealing with the filesproduced by the SDS software. During a single day of real-time operation, theApplied Biosystems 7900HT Fast Real-Time PCR System can generate over 200 MBof data. Without a strategy for distributing and archiving SDS-related files, the7900HT instrument can easily fill the hard drive of the computer within just a fewweeks of operation. See “Managing Sequence Detection System Data” on page 1-17for a discussion of management strategies.ArchivingSDS FilesDefragmentingthe Hard DriveTo conserve space on the computer hard drive, SDS files can be archived using a datacompression utility. The compression utility archives files by encoding them in acompressed form, thereby reducing the size of a file. SDS files can be compressedand decompressed many times.Several commercially available compression utilities are available. PKZIP and *.arcare archive formats common to the Microsoft Windows operating system.Applied Biosystems recommends defragmenting the hard drive of the computerattached to the instrument at least once every week or before fragmentation reaches10%. As the Applied Biosystems 7900HT Fast Real-Time PCR System is used andfiles are deleted and created, the free space on the computer hard drive eventually issplit into increasingly smaller blocks (called “clusters”). Consequently, as the SDSsoftware creates new files and extends old ones, the computer cannot store each filein a single block. Instead, the system will ‘fragment’ the files by scattering theircomponent pieces across different sectors of the hard drive.The fragmentation of SDS files decreases the performance of both the SDS softwareand the computer operating system. As the hard drive becomes fragmented, programstake greater time to access files because they must perform multiple seek operationsto access the fragments.7-54 Applied Biosystems 7900HT Fast Real-Time PCR System and SDS Enterprise Database User GuideDRAFTSeptember 1, 2004 11:39 am, CH_Maintenance.fm