On Wed, 5 Apr 2000, Paul Barton-Davis wrote:
>I have 3 of the IBM 18GB speedstars as well, I should try them
Mine are UltraStars, but whatever...
>out. But I wasn't aware (unbelievably) of the existence of an internal
>transfer rate. Now I know better.
So, where did you think the bits came from? You do know there's sector
heading, ECC, and padding in addition to "user data" on a disk?
>>Taged commands are off, there's a speed killer.
>
>Yes, I have some devices that don't like them, and I've never
>reenabled them individually for the disks. I should try this.
Gez, that's a simple edit of aic7xxx.c
>>> 10: 1740 1756 IO-APIC-level aic7xxx, RME Digi9652
>>
>>And you're sharing an interrupt. That'll burn a little speed.
>
>Yes, I know, its not very nice, and I still haven't found a way to
>force it to be otherwise. The AMI BIOS doesn't seem to play along with
>my attempt to assign different priorities to the slots.
It's not a major problem, but it does cost a few cycles.
>>Umm, I don't think so... 80MB/s is an LVD speed. You cannot have both LVD
>>and non-LVD hardware on the same cable in LVD mode. There doesn't appear to
>>be any isolation chip on that MB (and SuperMicro doesn't list one) so it's
>>actually _40_MB/s but that doesn't matter for the purposes here -- the bus
>>is faster than the drive. Besides, you've got too many devices to fit on a
>>proper SE FAST-40 (U2/SE) bus. Again, this is immaterial to speed.
>
>There are 3 SCSI connectors on the motherboard, one U2/LVD-SE, one
>regular old wide SCSI and one Ultra SCSI. The disks are the only
>things connected to the U2/LVD-SE connector. I got the impression from
>the adaptec site that if I set things up this way, I got an isolated
>U2/LVD bus. Is this not true ?
As I said, Supermicro doesn't say there's an isolator. And it doesn't
really matter.
--Ricky
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