Date: Tue, 11 Jun 1996 21:48:55 -0400 (EDT) From: David Miller <isdmill@gatekeeper.ddp.state.me.us> To: "Aaron D. Gifford" <agifford@infowest.com> Cc: freebsd-questions@freebsd.org, bsdi-users@BSDI.COM Subject: Re: Adaptec2940UW vs. BusLogicBT-958 (opinions?) Message-ID: <Pine.BSI.3.93.960611214219.16306A-100000@gatekeeper.ddp.state.me.us> In-Reply-To: <2.2.32.19960611210700.006ebe8c@infowest.com>
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On Tue, 11 Jun 1996, Aaron D. Gifford wrote: > Okay BSD users (both BSD/OS 2.1 and FreeBSD), which SCSI-3 UltraWide > controller is superior (performance wise), the BusLogic BT-958 OR the > Adaptec 2940UW? I've heard it both ways. Someone told me that the BusLogic > card has a larger tag queue and that such a feature made it superior. Probably does. If and only if the OS will issue more tagged IO's. Since neither of the OS's you mention do to any substantial effect, it doesn't really matter. > Another person explained that the Adaptec uses newer tag queue command > processing that is much faster than the older BusLogic technology, and that > makes the Adaptec superior. Same argument applies. If the driver for your OS of choice doesn't utilize the feature, it does you no good at all. > I'm planning on outfitting two machines with whichever controller appears > the better. I will be using SCSI-2 Fast&Wide drives to begin with, but will > later add UltraWide drives as they become available. If you really think that a 40 MB/s bus will get you any more io than a 20, you ought to try running IOzone against a memory filesystem. You may be suprised at what you find on either of your bsd's. I can't say about freebsd, but my understanding is that bsd/os 2.1 doesn't really take advantage of any of the W controllers, let alone the UW. Perhaps FreeBSD does with the 2940, but I won't base my production system on a set of drivers developed solely through reverse engineering. If Adaptec wants me to buy their product they can release the engineering specs required for my OS vendor to support them properly. Until then Buslogics makes at least as good a card. --- David Miller ---------------------------------------------------------------------------- It's *amazing* what one can accomplish when one doesn't know what one can't do!
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