Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!ssbell!dsndata!wayne From: wayne@dsndata.uucp (Wayne Schlitt) Newsgroups: comp.arch Subject: Re: disk rotation speed Message-ID: Date: 2 Aug 90 18:37:50 GMT References: <2635@mindlink.UUCP> <10048@pt.cs.cmu.edu> <1990Jul31.200043.5189@nlm.nih.gov> <1990Aug1.220440.20727@ico.isc.com> Sender: wayne@dsndata.UUCP Organization: Design Data Lines: 26 In-reply-to: rcd@ico.isc.com's message of 1 Aug 90 22:04:40 GMT In article <1990Aug1.220440.20727@ico.isc.com> rcd@ico.isc.com (Dick Dunn) writes: > [ ... ] In fact, you can see some high-end drives > designed with dual actuators to reduce rotational latency...the tradeoff > here is that it was apparently cheaper to add a second set of heads, servo, > r/w logic and all, than to deal with the problems of faster rotation. I have wondered about this for a long time. Are there many drives with more than one actuators? Why arent there more? I would think that this would not only reduce the rotational latency, but it could also do a lot to reduce the seek time. Depending on the smarts in the disk controller, this could make a big increase in real throughput. In the not so uncommon case of copying a file from one place on the disk to another location, you could have one actuator sitting and reading while the other one is doing the writing. Poof-da, zero seek time and possible zero rotational delay. Yeah, I know, you would have to either have two data paths to the disk or one data path that was quick real quick and a buffer so that you could keep both heads busy. You would also have to have a fast processor in order to keep the data flowing through quick enough to have zero rotational delay, but still, I could see this as a big win. -wayne