No, not the same. >From the description of the physical characteristics of the 3380 & 3390, it was clear that each actuator accessed independent platter surfaces. The R/W heads on different actuators did not access the same physical surface much less the same physical track.
The 3380 & 3390 hard drive modules each contained two functionally independent hard drives within a single module. Putting platters for both in one module housing reduced costs and size by allowing platters for two drives to have a shared drive shaft, shared bearings, and a shared drive motor. The Seagate design description clearly indicates two R/W heads accessing the same physical track. That sounds like they can at a minimum be used to cut rotational latency time in half, and maybe (not clear) even read or write different parts of the same track at the same time with the potential for doing a full-track transfer in only 1/2 revolution of the disk. If both are true, they have effectively doubled the peak transfer rate of the drive and cut the latency time in half without having to increase either the density or rotational speed of the device. Joel C Ewing On 12/20/2017 07:31 AM, Vernooij, Kees (ITOPT1) - KLM wrote: > The 3380 (3390 also?) had the same, one pack of disks with 2 independent > actuators on each side, representing 2 volumes. > > Kees. > >> -----Original Message----- >> From: IBM Mainframe Discussion List [mailto:[email protected]] On >> Behalf Of Tony Thigpen >> Sent: 20 December, 2017 14:19 >> To: [email protected] >> Subject: Re: Can anyone remember "drum" storage? >> >> From reading the description, it really just appears to the OS as two >> drives in one housing. >> >> Tony Thigpen >> >> John McKown wrote on 12/20/2017 08:08 AM: >>> It's not really a drum, but it is getting closer. Of course, for true >>> speed, one should go SSD. >>> >>> >> http://www.theregister.co.uk/2017/12/19/seagate_disk_drive_multi_actuato >> r/ >>> [quote] >>> >>> Seagate is increasing IO performance in disk drives by separating >>> read-write heads into two separate sets which can operate >> independently and >>> in parallel. >>> >>> The heads are positioned at one end of actuator arms which rotate >> around a >>> post at their other end to move the heads across the platter surfaces. >>> Thus, with an eight-platter drive, each read-write head is positioned >> above >>> the same cylindrical track on each platter and reads or writes to and >> from >>> the same disk blocks on each platter's surface. >>> >>> [\quote] >>> >>> >> ... -- Joel C. Ewing, Bentonville, AR [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
