software raid options

software raid options

[Bretton Vine]

Hi All

I'm new to the list so apologies if any of my questions have come up
before and been answered.

Given the costs of a hardware raid solution here in South Africa (3-4
times the cost of hardware at online retailers) I've opted for a
software raid configuration under Debian Linux.

Where I'm hitting a snag is in determining the ideal hardware setup. The
motherboard has an onboard ide controller but only two channels. I'd
like to run raid 5 and have investigated costs for purchasing two new
pci parallel ATA ide controllers, or one pci SATA ide controller.
(I don't want one controller under via chipset and another under a
different chipset - seems like things may go wrong in that situation)

1) Will one SATA ide controller suffice if I want to run four disks off
it, one acting as hot spare. (yeah I know s/w raid is over partitions).
I'm completely unfamiliar with SATA and don't know if you can run four
masters off four SATA connections on the same SATA pci card.

2) Other option is two have two duplicate pci parallel ide controllers
(leave the onboard Via chipset controller out of the equation) and run
two disks per controller. Is there anything I should be aware of if I'm
sticking in two pci ide controllers. Is this a suggested solution?

3) I've looked at the Promise SATA150 TX4 and the Promise Ultra133 TX2:
of these two which is better. Broad question I know, but I'm a bit
confused as to whether moving to SATA is even worth it just yet as the
costs are considerably higher than parallel ATA.

4) Is there any other brand of SATA/Parallel pci controller card that
will have few to none driver/kernel issues under Linux. Any particular
brand well supported and ideal?

Thanks in advance and once I have a clear idea of what I'm doing on the
initial hardware setup I'll probably have some more interesting
questions to ponder.

Bretton
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Re: software raid options

[Maarten J H van den Berg]

On Friday 27 February 2004 07:45, Bretton Vine wrote:

> Where I'm hitting a snag is in determining the ideal hardware setup. The
> motherboard has an onboard ide controller but only two channels. I'd
> like to run raid 5 and have investigated costs for purchasing two new
> pci parallel ATA ide controllers, or one pci SATA ide controller.
> (I don't want one controller under via chipset and another under a
> different chipset - seems like things may go wrong in that situation)

In my opinion you should use the onboard controller as well. And I say "as 
well" because you really really only should use one drive per cable, i.e. you 
do not use "slave" drives, only masters. You thus need one or several 
ultra133tx2 cards, depending on the amount of drives you have.

> 1) Will one SATA ide controller suffice if I want to run four disks off
> it, one acting as hot spare. (yeah I know s/w raid is over partitions).
> I'm completely unfamiliar with SATA and don't know if you can run four
> masters off four SATA connections on the same SATA pci card.

I am unfamiliar with SATA as well, but judging from this mailinglist I still 
have some doubts about some of the SATA cards' drivers. I may be mistaken 
though.  Just make sure before you buy any SATA card that it is supported.

> 2) Other option is two have two duplicate pci parallel ide controllers
> (leave the onboard Via chipset controller out of the equation) and run
> two disks per controller. Is there anything I should be aware of if I'm
> sticking in two pci ide controllers. Is this a suggested solution?

I use this myself on my 7 disk IDE raid5 setup. All are running off a couple 
(3 units I think) promise Ultra100TX /Ultra133TX2 and one off the mainboard. 
In addition I have an eighth disk which contains just the OS (the raid is 
userdata only) as first disk, thus also off the mainboard. This is not 
neccessary but it seemed a good idea at the time, and it circumvents any 
(possible) trouble regarding booting off raid5. But that's just me...

As an aside: it was quite a challenge to get 8 IDE disks each on its own 
channel inside a bigtower, what with cooling and cablemanagement... :-)

Maarten