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Re: pdc202xx_new, ataraid, pdcraid

Sandro Dentella wrote:

root argo-cd root # modprobe pdcraid /lib/modules/2.4.21-p3/kernel/drivers/ide/raid/pdcraid.o: init_module: No such device
Hint: insmod errors can be caused by incorrect module parameters, including invalid IO or IRQ parameters
/lib/modules/2.4.21-p3/kernel/drivers/ide/raid/pdcraid.o: insmod /lib/modules/2.4.21-p3/kernel/drivers/ide/raid/pdcraid.o failed
/lib/modules/2.4.21-p3/kernel/drivers/ide/raid/pdcraid.o: insmod pdcraid failed

I don't really understand when I need ataraid/pdraid. Should I need them if
I want to use md-tools linux RAID1 or (as I suspect) I only need it if I
want to use hardware raid?

I dicovered that I just needed to compile pdc202xx_new *into* the kernel. After compiling it into te kernel I could see all disks *and* modprobe pdcraid just worked flawlessly. And YES: devfs support is there so I could see all devices even /dev/ataraid/disc0/disc

#1)The promise controller doesn't do hardware raid. All raid occurs in the driver. The only hardware support is some bios code that allows you to boot off a raid 0 array.

So under linux all the (raid) job is accomplished by pdcraid/ataraid?

I mean that raid is done in the driver. It doesn't matter what driver you use. Or if you are using Linux, or windows. The promise fasttrak controller doesn't have a hardware raid engine!!

#2)You don't want any promise raid configured for linux md raid.

you mean I will not use a raid1 array defined into promise as base for
md. If this is what you mean I perfectly agree/undertsand

Yup. Of course this assumes you can revert your controller to a normal ide controller in the motherboard bios. Otherwise you may need to create a raid array in the promise bios for each disk. Each array would be composed of only a single disk. This give you bios drives to boot off.

 or you mean it wouldn't be reasonable to use (partitions from) single
 disks (hdg, hde) to create an array w/ md-tools?

#3)Linux software raid is better than promise's raid driver.

here you are comparing "Linux software raid" = pdcraid with
"promise's raid" = ft.o precompiled?

Software raid = Linux md driver Promise raid = Promise ft driver Ataraid = Linux ataraid driver.

In any case linux software (md) is better (IMHO) than the pdcraid driver. The Promise ft driver should be avoided at all costs.


 just to be sure, (i'm not always that *slow* ;-) since everything seems to
 work (I already made a trial installation on /dev/ataraid/disc0), is that
 a suggested way to use this controller?

That should work fine. I prefer the linux md driver, but other on this list are doing just fine with ataraid. Be aware that the ataraid or the promise driver will crash the system if you lose a drive.

Linux doesn't seem to see a lot of difference between BIOS setting ATA or RAID. It sees the array even if I set it to ATA. Should I leave to RAID?

Very last thing: when using md-raid, i try to put disks on different
controllers. Should I take such a care width pdc20276 too?

I generally happy with only one drive per channel.

Once you have their hardware. Never give it back.
(The First Rule of Hardware Acquisition)
Sam Flory  <sflory rackable com>

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