[dm-devel] dm howto?

[Guilherme Barros]

thx again for the info... more q's  follow...

On Jun 13, 2004, at 10:27 AM, christophe varoqui wrote:

>
>> for right now ill probably use mdadm for the boxes we _need_ to be
>> supported, and ill start playing with dm on my debian ones. Just as a
>> side, is there a dm patch for 2.4.x that i could try?
>>
> the multipath tools rely heavily on sysfs and 2.6 hotplug. There is a
> kernel patch for 2.4 on ftp://sources.redhat.com/dm/ but you won't get
> far with that.

thats what it looks like. i imagine 2.6 is not till rhel4?
for right now it seems that ill just have each server in the cluster on 
a different fabric, which should give me some measure of reliability.

>
>> is unloading/loading the module really the only way to rescan the bus
>> with the qlogic hbas? i hate having to take an outage to add a vdisk.
>>
> no, you got the following commands at disposal :
> echo "scsi add-single-device 0 1 2 3">/proc/scsi/scsi
> echo "scsi remove-single-device 0 1 2 3">/proc/scsi/scsi
>
> where
> 0 = host adapter #
> 1 = bus #
> 2 = target #
> 3 = lun #
>
> alternalively, you can google for a wrapper script written by Kurt
> Garloff (I guess) named scsi-rescan.sh

sweet, thx. HP also seems to have their version of the same thing. ill 
play with that for a bit.

>
>> could the RH kernel be built without REPORT_LUN? would that do it?
>>
>> whats your take on using the RH, HP, or qlogic versions of the hba
>> driver? is one better than the others? how does the failover work? is
>> there a doc somewhere with the module params?
>>
> That is all a question of support.
> For myself, I only use 2.6 for dev, which comes with the Qlogic
> maintained driver.

where can i find info on the qlogic hba failover setup? ive heard 
people talk about it but cant find any docs anywhere... what does it 
do? how does it work?


thx again!
-- 
Guil Barros - UALR Computing Services - Networks Project Manager
gfbarros at ualr.edu - http://www.ualr.edu - 501-569-3345
"Because I dislike being quoted I lie almost constantly when talking
	about my work." - Terry Gilliam