[email protected] (John McKown) writes: > https://www.theregister.co.uk/2017/12/19/seagate_disk_drive_multi_actuator/
latest from yesterday ... Seagate's HAMR to drop in 2020: Multi-actuator disk drives on the way Fast and slow high-cap disk lines coming https://www.theregister.co.uk/2018/03/21/seagate_to_drop_multiactuator_hamr_in_2020/ trivia: original 3380 had 20 track widths between each data track, "double density" cut spacing between data tracks to 10 track widths, and then was cut again for triple density. in the mid-80s there was work on veritical recording (higher bit density) and about the same time the "father of risc" gets me involved in his idea for wide disk head ... basically handle 16 (adjacent) data tracks with servo track on each side. disk formated servo track followed by 16 data tracks (followed by another servo track and 16 more data tracks). This would read/write 16 tracks in parallel ... something like the old 2301 drum that read/write four data tracks in parallel. For the 2301 drum it met (four times 2303 300kbyte/sec) 1.2mbyte/sec transfer ... which 1.5mbyte channels could handle. The problem for wide-head was 16 data tracks in parallel, each at 3mbytes/sec resulted in 48mbytes/sec transfer ... which no mainframe channel could handle ... even the introduction of ESCON in 1990 was only 17mbyte/sec. In 1988, I was asked to help LLNL standardize some serial stuff they were playing with which quickly becomes fibre channel standard and started out handling 100mbyts/sec concurrently in both directions (200mbytes/sec aggregate) ... but mainframe FICON protocol built on fibre channel didn't come along until much later (and heavy weight FICON protocol drastically reduced the native fibre channel throughput). FICON posts http://www.garlic.com/~lynn/submisc.html#ficon posts mentioning getting to play disk engineer in blgs 14 (disk engineering) and 15 (disk product test) http://www.garlic.com/~lynn/subtopic.html#disk -- virtualization experience starting Jan1968, online at home since Mar1970 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
