re recommendations for a local bus cache penio penev penev rockefeller edu wrote i have a maxtor mb on an isa ide controller although my machine is dx vlb i has the save transfer rate of mb s regardless of the variations of the isa bus speed i tested it with speed between mhz and mhz not any difference the problem is not the interface between the controller and the memory chris brinton brinton icd teradyne com wrote i also have a dx and a maxtor i have a local bus ide controller generic and i get kb s i tried swapping my local bus ide controller for an isa ide controller and my transfer rate went to kb s the specs for this drive show a maximum platter to controller transfer rate of mb s i dont know how to get there from here the local bus interface got me a little but certainly not as much as i had hoped i am also looking for a way to what is the deal with the ide transfer rates is anybody getting throughput anywhere close to the platter controller rate i haven t seen anything even close to the mb sec limit of the ide interface these drives are non interleaved aren t they here are the rates i get sequential read msdos c program that uses bios calls to read sector blocks sequentially from outside first track inward mhz bus mhz bus maxtor lxt kb sec kb sec quantum lps kb sec kb sec disk buffer read same c program but re reads the same block repeatedly so in effect is reading the ram buffer on the drive mhz bus mhz bus maxtor lxt kb sec kb sec quantum lps kb sec kb sec coretest v transfer rate seems to agree with above mhz bus mhz bus maxtor lxt kb sec kb sec quantum lps kb sec kb sec i managed to get hold of the quantum lps at product manual and it goes into excrutiating detail describing how the bits get from the platter through the controller and out the ide interface nowhere do i see anything like after the bits are whipped of the platter at high speed they sit around in a buffer to thaw before they are sent to the host even though i swear that s whats happening here are some relevent quotes from the manual data is transferred from the disk to the read buffer at a rate of mb s maximum mb s minimum my calculations show kb sec maximum and kb sec minimum disk spins at rpm with sectors per track on the outside and on the inside single burst errors of up to bits within one sector can be corrected on the fly in real time as they occur allowing a high degree of data integrity with no impact to the drive s performance i take this to mean error correction isn t the bottleneck for page mode operations the data transfer rate to and from the buffer ram is up to mb s this high transfer rate allows the at interface ic to communicate over the at bus at a data transfer rate of mb s while the dcs simultaneously controls disk to ram transfers so the thing can even do it s cache pre fetch while it s sending the requested sector it has kb read buffers for pre fetching i guess you could call that a cache so when i do a sequential read on the outer tracks why am i getting a measly kb sec when i should be getting around mb sec any of you hard disk engineers out there know wondering why my disks are so slow david o o ooo ooo david stam linux the choice of a gnu generation stam netcom com un x x r openlook gcc tex free
