[dm-devel] dmsetup target parameters

[christophe.varoqui at free.fr]

Selon Ling Hwa Hing <hwahing at nasioncom.net>:

> hi,
> I've got problem to use dmsetup. i read the documentation provided from
> http://christophe.varoqui.free.fr/multipath.html, man dmsetup, intro and some
> of the doc from google and the comments from the source code (can't
> understand the code) 
> I still dont really understand how this low level settings can effect to the
> multipath setup. 
> 
you don't need to use dmsetup if the multipath-tools work for you

> I'm able to create a few device without using the table file. but dont know
> how to use it. 
> dmsetup -j 8 -m 0 create impstor1 -u [uuid from uuidgen] --notable
> the device node is store at the /dev/mapper/
> 
yes : no table, no i/o

> i got no idea where to enter this entry like what describe in the website.
> 
> 0 35258368 linear 8:48 65920 (I do not know where to get the target
> parameters)
> 35258368 35258368 linear 8:32 65920
> 70516736 17694720 linear 8:16 17694976
> 88211456 17694720 linear 8:16 256
> 
this is just an example, like I said, you don't need to play with that.
in case you mind, though, here is how you can feed the tables :

echo "0 27262976 multipath 2 round-robin 2 0 /dev/sda /dev/sdk round-robin 2 0
/dev/sdc /dev/sdm" | dmsetup create myfcdev

> Here is an example of a multipath target :
> 0 27262976 multipath 2 round-robin 2 0 /dev/sda /dev/sdk round-robin 2 0
> /dev/sdc /dev/sdm
> 
good to see the tools work for you.
there, after execing "multipath", you should have a /udev/$wwid created.
you can format and play with that device node.

> 
> I'm using emulex driver for lp8000 its connect to compaq san. 2 lp8000
> installed. 
> the box see 4 scsi drive sdc,sdd,sde,sdf. i can only use it as a md device.
> with raidtab. 
> 
this SAN environment is tested and works ok with multipath-tools

> i read the doc for many many times. sigh... i really dont know where to
> start. and where to stop.
> 
It seems you already got what you want : just verify you have that /udev/$wwid node.

regards,
cvaroqui