PCI-X SCSI Controllers Question

[dajo]

Both of my drives are 15K SCSI, currently with an LSI 160 controller. I have an Ultra4 board coming so I'm wondering if the upgrade to a PCI-X SCSI controller would be worth it. For me, worth it means noticeably faster.

Wouldn't the PCI-X bus theoretically allow for a significant boost in transfer rates? Anyone here running SCSI using the PCI-X bus? Care to comment on how it compares to the 33MHz PCI bus?

 

[Peter]

You sure you'll have PCI-X on your future board, not just PCI-Express? NOT THE SAME THING!

And if you actually will have PCI-X, then just use that LSI U160 controller in that PCI-X slot. It'll at least run 64-bit wide 33 MHz PCI then, doubling its available PCI bandwidth. U160 SCSI is PCI-limited to about 100 MB/s in a standard PCI slot, and can reach full performance only in wider or faster slots.

 

[dajo]

I thought they were different names for the same thing. The board is a KN1 nforce4 Ultra board. Below is a link to manufacturer's specs, and some quotes.

KN1

Expansion Slot 1 x PCI Express x16 slot
2 x PCI Express x1 slots
3 x PCI slots

PCI Express
Delivers up to a 4x increase in graphics and 2x I/O bandwidth for smooth multimedia performance.

PCI Extreme
This slot can provide ultra signal quality for outstanding audio and video card performance.

Did some googling on these terms but I need to go to work now, and I don't understand the difference. Looks like one perhaps applies to the graphics port while the other replaces the PCI bus. Maybe you could clarify for me?

So, does this board have one pci express (graphics) slot, and 2 pci-x (cards like controllers, sound, etc.)?

The controller I'm thinking of getting is the LSI21320-R:

The LSI21320-R PCI-X to Dual-channel Ultra320 SCSI Host Bus Adapter Kit from LSI Logic® is ideal for workstations requiring high-performance throughput internally or externally. With 320 megabytes per second bandwidth and capability of up to 100,000 I/O per second performance, this card is suitable for applications where robust, large-volume data transmissions are needed. The Ultra320 SCSI Host Bus Adapter Kit includes a 42-inch Tripp Lite® internal LVD cable.

Both drives are u320. That card/cabling would work with the Cheetah 15K and Maxtor 15K I have, right?

 

[Peter]

And you'll plug that where? Get it already: PCI Express is not PCI-X!

 

[Bar81]

PCI Express is denoted as PCI-E, which is *completely* different from and incompatible with PCI-X

 

[dajo]

Interesting responses...

Guess what? If I already knew the answers to these questions I wouldn't have started this post, would I?

Nevermind - I'll try somewhere else.

 

[Peter]

What else do you need to know? On this board, you can plug your PCI-X card into an ordinary PCI slot and limit your U320 SCSI card to ~95 MBytes.

YOU CANNOT PLUG A PCI-X CARD INTO A PCI-E SLOT. This is all the information you asked for.

If you want to use a PCI-X card and make good use of it, you need to buy a mainboard with PCI-X slots. Is that so difficult to understand?

 

[Zepper]

I doubt your two drives are challenging your current card for bandwidth. So until you need to add more or faster drives, just use your current card. At the point where you add more and/or faster drives, start lookin at PCI Express x1 adapters. I think x16 is for graphics cards but not sure. I have not actually seen a PCI Express SCSI adapter. All I've seen are either 32-bit PCI (normal PCI slot) or 64-bit PCI (often called PCI-X or Extended PCI), many of which are backward compatible with the normal PCI slot.
. Normal PCI slot limits bandwidth to about 133 MB/sec. Your two drives together are unlikely to exceed that. Most of the PCI-X (and some normal, 32-bit) PCI) SCSI adapters are capable of 66MHz operation - if you can adjust your PCI slot(s) (ideally one at a time) to run at 66MHz instead of the normal 33, you could double the bandwidth.


.bh.

 

[Peter]

They might be close to saturating U160 SCSI, but they're most certainly saturating the PCI end of the affair already. The idea is right - move (even the same) SCSI adapter onto a faster bus, like PCI-X. The LSI U160 adapter is 64-bit 33 MHz, thus capable of twice the bandwidth it gets on a commodity mainboard.

PCI-E SCSI adapters just aren't here yet, and to be good and fast, they will need a 4x PCI-E slot - so yet again, workstation mainboard time.

 

[LED]

I've yet to see any PCI-E cards other than Graphics. If anyone has a link to any please post...

 

[statik213]

no mainstream scsi pci-e controllers yet; doubt if you would see much of a improvment, one thing you could do is run a bechmark on the drive and measure the performance of your drives to get an idea of if you're even pushing the bus to the level...

look for hdtach -great free (for personal use) hdd benchmarking software...

 

[Haden]

Originally posted by: LED
I've yet to see any PCI-E cards other than Graphics. If anyone has a link to any please post...

I while ago I was searching for pci-e nic, found
dlink but haven't bought/tried it yet

 

[LED]

Originally posted by: Haden

Originally posted by: LED
I've yet to see any PCI-E cards other than Graphics. If anyone has a link to any please post...

I while ago I was searching for pci-e nic, found
dlink but haven't bought/tried it yet

Thanks and gee that's 1 nice start although most PCI-E Mobo's already have a Nic inclusive but for a follow-up to Vid cards I guess it makes a little sense, although I thought SCSI, SATA, Firewire, and other cards might lead the way 😕

 

[Peter]

LSI have a shipping PCIE (4x) SCSI RAID card. The stuff is coming.

Those old enough might remember how long it took before the mid- and low-end I/O cards had made the jump from ISA to PCI. It's been years. PCIE is coming along much much quicker.