And a similar device: the 3350 with 2 fixed heads, addressing 1 cylinder each. Used a.o. for IMS WADSs.
Grtn, Kees. > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Allan Staller > Sent: 20 December, 2017 15:17 > To: [email protected] > Subject: Re: Can anyone remember "drum" storage? > > "pseudo-drum" - STK4305. I remember it well <sigh> > > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Joel C. Ewing > Sent: Wednesday, December 20, 2017 8:15 AM > To: [email protected] > Subject: Re: Can anyone remember "drum" storage? > > I don't think so. Says each R/W head accesses same disk blocks, and > there would be zilch improvement in speed if they were simply seen by OS > as two independent disks. By electronically selecting which of the two > heads to use to read the track based on which sees the start of the > desired block first, you cut the rotational latency time in half. With > a single R/W head the only way to get the same reduction in latency > delay would be to double the rotational speed of the platter, which > might cause greater problems. > J C Ewing > > On 12/20/2017 07:18 AM, Tony Thigpen wrote: > > 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. > >> > >> https://apac01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww > >> .theregister.co.uk%2F2017%2F12%2F19%2Fseagate_disk_drive_multi_actuat > >> or%2F&data=02%7C01%7Callan.staller%40HCL.COM%7C1e585afeeaf14753335808 > >> d547b42536%7C189de737c93a4f5a8b686f4ca9941912%7C0%7C0%7C6364937614319 > >> 95373&sdata=7BNHk4Ci%2Fq8zLD%2BgBDHrtFQOcgyBXiT1kUg1nK3fD6I%3D&reserv > >> ed=0 > >> > >> > >> [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 > > > > -- > Joel C. 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