[Pc_Support] Re: 68-pin SCSI card for Linux box .... -- i865/875 = desktop (not workstation/server)

[Bryan J. Smith]

On Tue, 2006-06-27 at 17:29 -0500, William A. Mahaffey III wrote:
> I understand this point quite well, how do I check that ? I have 3
> HDD's hooked up to the onboard (Foxconn 865A-01 i865 mbd) IDE
> controller, I didn't think that they went through the PCI bus, just
> other peripherials (NIC's, for example).

_All_ Intel i8xx series MCH designs have a single ICH that connects via
a 64-bit at 66MHz (533MBps) PCI bus.  Then virtually _all_ peripherals use
a _shared_ 32-bit at 33MHz (133MBps) PCI bus that is bridged to the ICH's
533Mbps uplink to the MCH.  The NIC may or may not be such -- depending
on the ICH.  I'm quite sure _all_ ATA (and SATA) channels are "shared"
on that 32-bit at 33MHz (133MBps) bus.

That's because *100%* of i8xx systems are designed for _desktop_ usage,
_not_ server (or even workstation for that matter).  Anyone who tells
you otherwise should be slapped silly.

Intel's "equivalent generation" workstation/entry-server chipset is the
E72xx series with an _optional_ Intel 6x00 PCI64/PCI-X series hub
_separate_ from the ESB6300 ICH (the workstation/server equivalent of
the i8xx ICH).  Their professional server chipset is the E75xx series.
Both are based on the ServerWorks ServerSet III/IV "Grand Champion" (GC)
PCI64/PCI-X bridging.

The newer i9xx series MCH designs have a single ICH that connects via
4-8 PCIe channels.  Several of those channels are often used for NIC and
SATA channels.  In addition to the E723x/753x series workstation/server
chipsets with PCIe (as well as with optional 6700 PCI-X bridge), there
is a new Intel 5000 series that natively does PCIe (with optional 6700
PCI-X bridge).

[ NOTE:  We've covered this before.  The i865/875 has only 1/8 - 1/16th
the bridged PCI I/O of _any_ E72xx/75xx chipset.  The i865 should
_never_ be used in a production environment and the i875 is definitely a
_desktop_ only chipset.  Do not use it as a power workstation or not
even as an entry server. ]

> I am backing stuff up from the HDD's on *this* box to the new tape
> drive, *after* this box gathers its near-line backup over the network
> from the other 4 boxen. I just ordered the above card, BTW, thanx :-).

But understand, the transfer still requires _separate_ transfers for:  
- Disc to memory
- Memory to tape

So 2x the transfer.  For LTO-1, you're probably okay as long as the
system is doing _nothing_ else.  But for LTO-2, you're definitely
saturating the 32-bit at 33MHz PCI badly.


-- 
Bryan J. Smith           Professional, technical annoyance
mailto:b.j.smith at ieee.org     http://thebs413.blogspot.com
----------------------------------------------------------
The existence of Linux has far more to do with the breakup
of AT&T's monopoly than anything Microsoft has ever done.