Hi Veena,
On Wed, 9 Jan 2008 15:15:38 +0530, "T S, Veena (STSD)" wrote:
> Purpose of the patch-
> -- To introduce the prio_callout attribute into the multipath section of
> the configuration file.
The prio_callout feature has been changed to the libprio.
Please check the latest Christophe's git.
> -- To implement the preferred path feature in device mapper.
>
> Uses of the patch-
> -- Prio_callout attribute in the multipath section allows users to write
> callout routines,which can be specific to a LUN.
> -- When it is known the performance of one of the path is better than
> the other available paths for a particular LUN, the user can set it as
> preferred path.
How about opposite case such as the performance of some paths are
better than the one backup path for a particular LUN?
So if we can specify some preferred paths, that may be more useful.
> +int main(int argc, char * argv[])
> +{
> +
> + char path[FILE_NAME_SIZE];
> +
> + if(argv[1] && argv[2])
> + {
> + if(!strncmp(argv[2],"/dev/",5))
> + strcpy(path,argv[2]+5);
> +
> + if(!strcmp(path,argv[1]) || !strcmp(argv[1],argv[2]))
> + {
> + printf("%u\n", HIGH);
> + return 0;
> + }
> + else
> + {
> + printf("%u\n", LOW);
> + return 0;
> + }
> + }
> + return -1;
> +}
This prioritizer looks that we need to specify the preferred path
by devnode or major/minor, right?
If so, it doesn't work reliably.
Both devnode and major/minor may vary for each system reboot.
It's horrible to check and change the config file after every reboot.
We should be able to use more persistent name to specify a path,
though I don't have a good idea now...
Thanks,
Kiyoshi Ueda
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