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Re: [vox-tech] a few pre-install questions
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Re: [vox-tech] a few pre-install questions

Quoting dylan (dylan@iici.no-ip.org):

> here is the motherboard that the machine will be based on:
> http://www.asus.com/products/server/srv-mb/pc-dl/overview.htm
> from the product description:
> The PC-DL Deluxe offers the most complete RAID solution. A Promise SATA
> controller offers RAID 0, 1 and 10 functions with Max. 2 UltraATA 133 ports
> and 2 SATA HD ports, enabling users to build a RAID array with any 2, 3 or 4
> of the ports. With unique multi-RAID function, RAID 0 and RAID 1 array can
> co-exist. 
> .... not sure how to convert this into the chipset information that you had
> requested... any ideas?

Er, this is something even a bit more complex that I've seen on a few
systems, and until recently it confused _me_ mightily.

That Promise chip is used for what is often (rather bluntly) called
in Linux circles "fakeraid" functionality -- manufacturer-specific
software RAID, which must be implemented inside each OS's drivers,
relying on a bit of BIOS support from the chip.  In this regard, the 
Promise chips are a wee bit better than their competition from Silicon
Image, SiS, VIA, Nvidia, Intel, and HighPoint:  It at least provides a
hardware-level XOR engine and RAM for RAID calculations inside the chip.
Management of the RAID logic, though, is still offloaded to the drivers
and the host CPU -- and the RAID disk format it supports is still

You can download, if you wish, proprietary, binary-only Linux drivers from
Promise for the proprietary disk format.  One alternative, that of
instead using Linux's own (superior) "md" software RAID driver, would be
great for Linux but incomprehensible to WinXP alternate boot.  The third
alternative would be to forego RAID disk modes, and ignore the Promise chip.

What used to confuse me is that the Promise chip isn't providing basic
IDE functionality.  To see what does, you have to look further down the
product-description page:

>  ICH5R with Integrated SATA and RAID
> Intel is the worlds first chipset maker to integrate Serial ATA (SATA)
> and RAID functions into the South Bridge. The latest ICH5R chipset now
> delivers 150MB/s fast data transfer (SATA) and striping performance to
> enhance computing efficiency.

This is of course one of the PIIX-architecture "ICH5" chips I mentioned
in my earlier message, and is what provides your basic block-device
(mass storage) functionality.  In addition, Intel includes its own
variant form of fakeraid (manufacturer-proprietary software RAID)
functionality in these chips, called "ISW RAID" (Intel Software RAID).  

As mentioned, the old drivers/ide drivers collection includes "piix", a
block-device driver for ICH stuff, which works more-or-less OK with
ICH5 starting with kernel 2.4.22 -- but with some reported tendency to
hang.  It's generally considered that libata's lib_piix driver is better
for Intel's SATA PIIX chips.

Although Intel's proprietary software RAID isn't supported in the
general case, the one exception is RAID0 (disk spanning), which you
_can_ support in Linux (2.4.26 and later) if using one of these chips,
because of the iswraid patch that hooks into the necessary BIOS call.
But regular, redundancy-type RAID modes (RAID1 mirroring, RAID5, etc.) 
aren't supported at all.

Anyhow, if you're loading Debian on this box, you might want to use the
late-beta "sarge" installer, or something similar that gives you a 2.6
installation kernel.

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