"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]
>>
>>
>
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--
Joel C. Ewing, Bentonville, AR [email protected]
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