Messages in this thread | | | Subject | Re: [OFFTOPIC] Re: disk head scheduling | From | Paul Flinders <> | Date | 22 Mar 1999 20:30:00 +0000 |
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"Richard B. Johnson" <root@chaos.analogic.com> writes:
> This means that read amplifiers that used to handle data at up > to 10 MHz are now handling data at 800 Mhz to 1 GHz. You can > check the numbers yourself. The bits per second that travel under > the read head is now much greater than the bits per second that > any I/O interface can handle. This means that sector interleave, > spiral compensation, and other tricks are now worthless because > nothing you do along these lines will allow you to actually use > data as fast as it becomes available. The data just arrives too > fast. Because of this, sectors are no longer interleaved.
Could you provide a reference to support those transfer rates - the Quantum Atlas III which looks fairly modern is specified as having internal transfer rates between 110 and 180 Mega bits per second (see http://www.quantum.com/products/hdd/atlas_III/specs.html), IBM's Ultrastar 36XP 3.5 is specified at 143.2 to 231.2 Mbits/sec (see http://www.storage.ibm.com/hardsoft/diskdrdl/ultra/36xpdata.htm) and the best Seagate drives top out around 264Mb/s - these are comfortbly less than current SCSI transfer rates of 80MB/s(= 640 Mb/s) which are themselves are easily accomodated by a 32bit, 33MB/s PCI bus (and Fibre channel is even faster) so I'd say the interfaces are still faster than the physical media.
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