[twix]

I replaced a relatively modern SCSI disk in my Indigo R4000/100 with a ZuluSCSI device. This is is more much quiet solution, and hopefully puts a bit less stress on the ageing power supply.
Everything functions correctly, but performance is not stellar, with diskperf results not exceeding 3.5 Mb/s. I was expecting more. I tried to test the device in both sync and async mode (set with scsicontrol) but this does not seem to have any effect. The ZuluSCSI logfile indicates that the connection starts up in sync mode.
I then put the hardware SCSI disk back and tested that, and results were comparable to those of the ZuluSCSI device. Nothing higher than 3.5 Mb/sec. So it would seem that the type of SCSI device is not the issue.
Is this what I can realistically expect from my Indigo, or is something wrong here? Can anybody provide some comparison data for this machine?