Xref: utzoo comp.sys.dec:428 comp.periphs:658 misc.wanted:1530 comp.misc:1572 Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!phri!roy From: roy@phri.UUCP (Roy Smith) Newsgroups: comp.sys.dec,comp.periphs,misc.wanted,comp.misc Subject: Re: Wanted: Good disk drives for VAX 11/785 Message-ID: <3075@phri.UUCP> Date: 17 Dec 87 16:42:04 GMT References: <1917@ho95e.ATT.COM> <181@tijc02.UUCP> Reply-To: roy@phri.UUCP (Roy Smith) Distribution: na Organization: Public Health Research Inst. (NY, NY) Lines: 30 In article <181@tijc02.UUCP> seb022@tijc02.UUCP (Scott Bemis) writes: > I currently am using two CDC 9772 disk drives [...] Carefully controlled > benchmarks showed the these disk drives to be 43 percent faster than the > RA81 disk drives. The 9772's may indeed be a very good drive (I don't know, I've never seen one), but to claim that it is fast just because it beats the pants off an RA-81 is absurd. The RA-81's are slow by any modern standard. According to the manufacturer's specs, the RA-81 has a 28 ms average seek time (actually, they quote it as "average positioning rate", whatever that means). The Fuji 2351 Eagle, for example, quotes 18 ms. I only pick the 2351 because it is of about the same vintage as the RA-81, both being introduced about 3-4 years ago or so. The difference is that the Eagle is still considered a reasonable drive to buy (although clearly the last few years have given it some competition) while the RA-81 was old when it was introduced. You can also buy Eagles (and, I suspect, most SMD disks) for about half the price per Mbyte of an RA-81. To be fair, the RA-81 was a radical departure in disk subsystem design. A lot of the smarts that used to be in the kernel-resident driver are now in the controller. I don't know how much the Unix drivers take advantage of the ability of the controllers (such as the most common UDA-50) to optimize disk operations. I suspect very little. With smarter and smarter controllers (such as the HSC-[57]0), and drivers designed to take full advantage of the hardware the RA-81 (and RA-82) may indeed come into their own. I tend to doubt it however. -- Roy Smith, {allegra,cmcl2,philabs}!phri!roy System Administrator, Public Health Research Institute 455 First Avenue, New York, NY 10016