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Re: [dm-devel] dmsetup target parameters

christophe varoqui free fr wrote:
Selon Ling Hwa Hing <hwahing nasioncom net>:

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
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.

How are you making this node? For me the dm sysfs name is dm-* (dm does not look like it currently supports passing a uuid to alloc_dev which sets the gendisk name), so udev is making dm-*. Is multipath or libdevmapper making it or is it udev? dmsetup ls does show the wwid though.

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