Speed of SCSI controller

[desantii]

Just curious I have a a SCSI to IDE converter and use a GVP combo board in my A2000, the speed reported in sysinfo is 2,100,000 bytes/sec but if I use no accelerator and GVP HDD controller I get 2,300,000 as the speed. Does it make sense that an unaccelerated HDD controler gets higher speed that the controller of an 030 50mhz? If so is there any benefit of running SCSI of the acclerator vs the ZII HHD controller?
 
Just as reference, the same setup in an A3000 030/25 gives me 2,900,000 as speed

[Damion]

Just curious I have a a SCSI to IDE converter and use a GVP combo board in my A2000, the speed reported in sysinfo is 2,100,000 bytes/sec but if I use no accelerator and GVO HDD controller I get 2,300,000 as the speed. Does it make sense that an unaccelerated HDD controler get higher speed thatn the controller of an 030 50mhz? If so is there nay benefit of raunning SCSI of teh acclerator vs the ZII HHD controller?
 
Just as refrence, the same setup in an A3000 030/25 gives 2,900,000 as speed

Couple of points:

1. According to Ralph Babel, the raw transfer rate of GVP accelerators (w/33C93A SCSI) is slower than the GVP Zorro SCSI cards. Best case scenario, 2.3 MB/s, vs 3.5 MB/s (Z2 limit) with a Zorro card.

2. Even so, I would stick with the accelerator SCSI. DMA into accelerator RAM is much better than copying data across the (non-DMA) Z2 bus. The system should remain a bit more responsive overall.

3. Make sure synchronous transfers are enabled in the RDB.

4. Try a better measuring tool, like RSCP or Ralph's RawScsiSpeed.

[desantii]

Ill try those tools tomorrow. How do I enable the RDB synchronous transfers ?

Also related, I have 8mb on the accelerator and 8mb on the GVP HDD controller, is there a system slowdown by having 32bit and 24bit ram?

[Damion]

Ill try those tools tomorrow. How do I enable the RDB synchronous transfers ?

Try HDInstTool or RDBFlags.

Also related, I have 8mb on the accelerator and 8mb on the GVP HDD controller, is there a system slowdown by having 32bit and 24bit ram?

It can, if/when the RAM is allocated. (You'll be heavily limited by the Z2 bus in that case. Even Z3 RAM is dog-slow.) Naturally, maxing out the accelerator would be the best option, but my guess is the accelerator memory has higher priority and will be used first, so it shouldn't be a major issue.

[Damion]

double post