XRBEO@VPFVM.BITNET (Bruce O'Neel) (01/28/88)
Have a question regarding ra82s vs a SA482. We've been told that on a BI bus machine (8250), we can use two KDB50 disk controllers to connect the machine to either 4 RA82s or 1 SA482. The result of using a two KDB50s is that we would get higher i/o through put because the two KDB50s would work in parallel. Is this true? Thanks in advance for you answers... -------
XRBEO@VPFVM.BITNET (Bruce O'Neel) (01/28/88)
----------------------------Original message---------------------------- Have a question regarding ra82s vs a SA482. We've been told that on a BI bus machine (8250), we can use two KDB50 disk controllers to connect the machine to either 4 RA82s or 1 SA482. The result of using a two KDB50s is that we would get higher i/o through put because the two KDB50s would work in parallel. Is this true? Thanks in advance for you answers... -------
thierbac@umbc3.UMD.EDU (Ed Thierbach ) (02/09/88)
In article <8802060354.AA02754@ucbvax.Berkeley.EDU> XRBEO@VPFVM.BITNET (Bruce O'Neel) writes: >Have a question regarding ra82s vs a SA482. We've been told that on a >BI bus machine (8250), we can use two KDB50 disk controllers to connect >the machine to either 4 RA82s or 1 SA482. Actually, 1 SA482 is 4 RA82s in one (big) box. As far as I know, each drive is cabled separately, just like the RA81 'four-pack' you can get. (We're currently evaluating them against the SI93C drives from System Industries). > The result of using a two >KDB50s is that we would get higher i/o through put because >the two KDB50s would work in parallel. > Is this true? Thanks in advance for you answers... What you would do is hook up 2 drives to 1 controller and the other 2 drives to the other controller. (At least I don't *think* you can dual-port disks between KDB50s, the way you can with HSCs.) Since one controller can transfer data from only 1 drive at a time, this allows 2 simultaneous data transfers. The trick is to spread your I/O load evenly across the 2 controllers. For example, you may want to put your secondary page and swap files on the controller that *doesn't* have your system disk on it. You also probably wouldn't put two high-throughput databases on the same controller (much less tht same disk). Hope thi helps! --- Ed Thierbach VAX System Manager Roy F. Weston, Inc. (yes, formerly of the University of Maryland, University College)