Re: Promise SATAII150 TX4 or raidreconf broken - answer

[Eyal Lebedinsky <eyal@eyal.emu.id.au>]

Tyler wrote:
> Eyal Lebedinsky wrote:
> 
>> Executive summary: it is not the TX4. It is not really raidreconf.
>> You must specify the parity-algorithm in raidtab because the
>> raidreconf default is not what one expects.
[trim]

> Nice work Eyal :)
> 
> Now all we need is a patch for raid-reconf to fix default behaviour? :D
> 
> Regards,
> Tyler.

Well, as simple as this looks, I have little understanding of what
goes on here. For example, looking at raidtools-1.00.3, I see this:

This is defined in three source files, as well as in common.h

# define RAID5_ALGORITHM_LEFT_SYMMETRIC        (2)

In prconv.c, readboth.c, rrc_raid5.c and sectors.c the algorithm
hard set:

static unsigned long
raid5_compute_block (... whatever ...)
{
        int algorithm = RAID5_ALGORITHM_LEFT_SYMMETRIC;
	...
	/* Select the parity disk based on the user selected algorithm */
	switch (algorithm) {

I cannot see how 'algorithm' can be altered at all here, so I do not
think that these programs respond to the raidtab algorithm at all.

In short, maybe raidreconf should not only default to left-symmetric
but refuse any other algorithm if it needs to cooperate with the other
programs here.

Better someone who knows this area does this. The actual setting
of a default is simple.

-- 
Eyal Lebedinsky (eyal@eyal.emu.id.au) <http://samba.org/eyal/>
	attach .zip as .dat