I remember being taught about 'drums' whilst completing my initial IT training course and - at the time - the HM Stationery Office system in Norwich, an ICL 1907 under GEORGE4, - had one, apparently. But I never saw it.
Later on in my career, I learned that Burroughs marketed a device under the name of 'head-per-track disk'. I never did learn if it actually had one R/W head for each track of disk, but response time was blazingly fast for the time. I can't help thinking that there's nothing new under the sun. Sean On 20 December 2017 at 15:22, Mark Jacobs - Listserv < [email protected]> wrote: > When I started working in the field, 1979, they had a couple of 2305 > devices attached to a 3033 processor. They used it for PLPA and COMMON > paging devices if I remember correctly. > > Mark Jacobs > > > Joel C. Ewing <mailto:[email protected]> > > December 20, 2017 at 10:05 AM > > 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 > > <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 > > > > > > Please be alert for any emails that may ask you for login information > > or directs you to login via a link. If you believe this message is a > > phish or aren't sure whether this message is trustworthy, please send > > the original message as an attachment to '[email protected]'. > > > > Tony Thigpen <mailto:[email protected]> > > December 20, 2017 at 8:18 AM > > 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_actuator/ > > <http://www.theregister.co.uk/2017/12/19/seagate_disk_drive_ > multi_actuator/> > > > > > > [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] > > > > > > > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO IBM-MAIN > > > > > > Please be alert for any emails that may ask you for login information > > or directs you to login via a link. If you believe this message is a > > phish or aren't sure whether this message is trustworthy, please send > > the original message as an attachment to '[email protected]'. > > > > John McKown <mailto:[email protected]> > > December 20, 2017 at 8:08 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_actuator/ > > <http://www.theregister.co.uk/2017/12/19/seagate_disk_drive_ > multi_actuator/> > > > > [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] > > > > > > -- > > I have a theory that it's impossible to prove anything, but I can't prove > > it. > > > > Maranatha! <>< > > John McKown > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO IBM-MAIN > > > > > > Please be alert for any emails that may ask you for login information > > or directs you to login via a link. If you believe this message is a > > phish or aren't sure whether this message is trustworthy, please send > > the original message as an attachment to '[email protected]'. > > > > -- > > Mark Jacobs > Time Customer Service > Global Technology Services > > The standard you walk past is the standard you accept. > Lt. Gen. David Morrison > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
