Adaptec SCSI Controller?

[SuperDave1685]

Hey guys.. I was wondering if anyone could shed some light on the AIC-7870 PCI SCSI controller.... I found one in an old pc my neighbor was going to throw away and he had it paired with an Seagate HD. Specs (http://www.seagate.com/support/disc/scsi/st34371n.html). I can't seem to find any information about this controller. I was wondering how well will it perform compared to my current 80GB IDE drive... I know SCSI drives are faster than their IDE counterparts usually, but this card appears its older and I'm don't know how much of a performance increase I'd see- if any... Thanks for any help guys!

-Dave

[terran2k]

ur ide is faster if the scsi is pretty old

[Xaotic]

Throw them both away. The 7870 is a 40MB/s synch chipset. It would cripple your performance. It would be like going back to an ATA-33 controller.

[SuperDave1685]

ohhhhh ok Xaotic.... thanks for the info.... but doesn't a SCSI drive read and write at the same time unlike an ID drive?

[Xaotic]

Commands can go up while data is being read, but the drive doesn't do both at the same time. Actually, in terms of write speeds, the drives are a bit slower than IDE. The default method of writing is write, then read and CRC with the data in the buffer. This assures that the data is written correctly. Since the head is in the same place, only rotational latency applies and it's a good deal faster than a seek and read. If the CRC comes back as bad, the data is rewritten elsewhere and that sector is dynamically reallocated. The speed of the bus comes into play when there are multiple drives on the bus and high IO queues. Commands are sent to the drives and they take turn bursting data down the pipe. A single U160 channel with two fast drives can get close to the full STR of each drive down the pipe due to the firmware optimizations of the controller and drives.

I'd still try to avoid U2, 40MB/s bus speed devices like the plague. They will generally have a narrow 16bit bus(50 pin IDE type connection) as well. U2W(80MB/s) and U160 devices are cheap and offer much better performance, but it's better for current, non high IO, non server, systems to stick with SATA or PATA IDE with high areal density on the platters. This gives better STR and usually fairly decent disk access times as well. The drive you have linked has a 9.4ms read access time. It's not clear, but that probably doesn't include disk latency. True disk access time would be in the 13.5ms range and be slow, loud and very hot. Your 120GB Maxtor will blow this thing out of the water performance wise.

[SuperDave1685]

oh wow Xaotic... :bows down:: Thanks for the abundance of info...well guess my decision is clear then... no old SCI for me lol.... but I imagine it'd do adequately for my upcoming Win2K folding and DIMES rig :)