[email protected] (Joel C. Ewing) writes: > Clearly from the picture the Seagate really is like the 3380/3390 > solution. Two completely independent actuators giving the appearance of > two drives in one unit with a shared drive shaft and motor. The > doubling of throughput is ONLY because you have two drives that can be > accessing or preparing to access totally independent data at the same > time, not because of any faster access to a block of data or multiple > blocks of data on a single track of one of those devices. Dang! My > interpretation would have been a much more intriguing device.
recent ref http://www.garlic.com/~lynn/2017k.html#22 little old mainframes, Re: Was it ever worth it? http://www.garlic.com/~lynn/2017k.html#44 Can anyone remember "drum" storage? or ibm 2302 IBM System/360 Component Descriptions- 2841 and Associated DASD <a href="http://www.bitsavers.com/pdf/ibm/28xx/2841/GA26-5988-7_2841_DASD_Component_Descr_Dec69.pdf 2302 (never heard of any actually installed) pg59-63 (pg 59 picture looks a little bit like the later 2305 fixed-head disk picture but not fixed-head per track). has two access mechanism, one for the inner 250 tracks and one for the outer 250 tracks (figure 46, pg 60) note that 2301 (fixed-head track) drum transferred four heads in parallel for 1.2mbyte/sec transfer (compared to 2303 319kbyte/sec transfer) and the 2305m1 transfered to heads in parallel for 3mbyte/sec transfer compared to 1.5mbyte/sec 2305m2 (mod1 also had heads offset 180 degrees on same track so it also cut avg. rotational delay in half ... but mod1 physically had the same number of heads, so only had have the tracks and half the capacity) -- 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
