CompuServe Messages

Chris: Most drives need to do a seek to initiate a degauss cycle, and the process can take over 100 ms. It needs to be repeated every 500 seconds or so on a standard Seagate ST-12550N drive, and every 250 seconds or so on a Maxtor MXT-540S drive. Thermal recal is worse, and can take over a second. I don't have details on how Seagate has optimized their drives for PAR use – I imagine they start a degauss cycle at the begining of a large block transfer command, giving 500 seconds of uninterrupted data. Micropolis has developed an embedded degauss and thermal recal cycle which take 11 ms and 30 ms respectively. The drive can maintain a 2.9 MB/s *worst case* data transfer all day long – with no interruptions. That is enough for good video quality. Unfortunately, the feature is is only available on their 2210AV and 2217AV Fast SCSI-2 drives – not on IDE drives. Because of this, the Seagate IDE units (with special firmware) are probably the best bet for PARs.