[dm-devel] dmsetup target parameters

Mike Christie mikenc at us.ibm.com
Wed May 19 09:07:48 UTC 2004


christophe.varoqui at free.fr wrote:
> 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.
> 

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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