[dm-devel] [PATCH RFCv2 10/10] dm-dedup: documentation

[Vivek Goyal]

On Thu, Aug 28, 2014 at 06:16:50PM -0400, Vasily Tarasov wrote:

[..]
> +Example
> +=======
> +
> +Decide on metadata and data devices:
> +   # META_DEV=/dev/sdX
> +   # DATA_DEV=/dev/sdY
> +
> +Compute target size assuming 1.5 dedup ratio:
> +   # DATA_DEV_SIZE=`blockdev --getsz $DATA_DEV`
> +   # TARGET_SIZE=`expr $DATA_DEV_SIZE \* 10 / 15`

Is above correct? With dm dedupe ratio of 1.5, target size
should be (15/10) * DATA_DEV_SIZE and not vice-a-versa?

> +
> +Reset metadata device:
> +   # dd if=/dev/zero of=$META_DEV bs=4096 count=1
> +
> +Setup a target:
> +	echo "0 $TARGET_SIZE dedup $META_DEV $DATA_DEV 4096 md5 cowbtree 100" |\
> +				dmsetup create mydedup
> +

I setup a target and did "dmsetup table" and "dmsetup status" and they
both seem to be outputting same thing. I think output of "dmsetup table"
is wrong. As per the man page of dmsetup, you are supposed to output
the table in a format which can be directly feedback into tagrget for
loading.

#dmsetup table
testdedup: 0 2930287752 dedup 244190646 244190646 0 0 4096 8:32 8:48 0 0
0 0 0 0

#dmsetup status
testdedup: 0 2930287752 dedup 244190646 244190646 0 0 4096 8:32 8:48 0 0
0 0 0 0

Thanks
Vivek