SCSI compatibility

[bliab]

Hi,

My machine has an onboard Adaptec 7890 (called 2940 equivalent) Ultra2/Wide LVD controller. Most of the drives I can find for sale now are described as Ultra160 and/or SCSI-3. Will these drives work with my adaptor if they have the right interface (68 pin LVD)?

Thanks,
bliab

 

[SCSIRAID]

Will work fine......

UPDATE:
Demon's post made me look a little deeper. The Adaptec AIC-7890 is a 32 bit PCI Ultra2 controller chip. As Demon pointed out... your real xfer rate depends on which board you have. If you have 50 pin connector it will go Ultra2 narrow = 40MB/sec. If it has a 68 pin connector then it goes Ultra2 Wide = 80MB/sec.

Sorry for the poor quality initial post.... It still works fine though 😉

 

[Zepper]

2940 is Single Ended, NOT LVD. Most drives are backward copabible. You will need an active terminator to plug in the last socket on your drive cable as no LVD hard drive has on-board termination.
.bh.

 

[Demon-Xanth]

The 2940 is a series, if it is just 2940 and you only have a 50 pin connector, you have a SCSI2 interface. However if it has a letter following it it can go faster.

2940: SCSI2 (10MB/s)
2940W: Wide SCSI2 (20MB/s)
2940U: Ultra SCSI2 (20MB/s)
2940UW: Ultawide SCSI2 (40MB/s)
2940U2W: U2W SCSI (80MB/S)


With adapters they are backwards compatible, but taking a fast drive down to SCSI2 would be kind of a waste.

 

[MereMortal]

bliab,

The 7890 chip is U2W like you stated (you confused some people with the 2940 equivalent). You can use U160 drives on this controller, but the peak bandwidth will be limited to 80MB/s instead of 160MB/s. With one (or even two) drives, the drives won't have the throughput to tax this limit.

 

[bliab]

Cool... Thanks for the help guys,
bliab