[dm-devel] each device filtering for multipath

[christophe varoqui]

Merged, thanks

Still need to be more clever in the blacklist function though ... like a
regexp parser.

On mer, 2005-03-30 at 10:03 -0500, k-ueda at ct.jp.nec.com wrote:
> Hello,
> 
> I think that finer-grained device filtering (e.g. by each device)
> is needed in multipath-tools.
> Has anyone already started tackling this feature?
> Any comments about following approach are welcome.
> 
> 
> Background
> ----------
> Problem#1 : Multipath command configures not only multipath devices
>             (like Fibre Channel storages) but also local devices
>             (like SCSI disks) as multipath.
>             Then, as dm holds the reference to the source device,
>             local devices can't be used through /dev/sd* name.
> 
> Problem#2 : Even for Fibre Channel storages, there is a case such that
>             we need to configure multipath for one but don't want for
>             the other.
> 
> We have 2 options to configure specific devices only.
> 
>   o Specify a device name as multipath command argument.
>   o Specify white lists (vendor/model combination) in scsi_id.config,
>     and don't use -g option for scsi_id callout.
> 
> But these are not enough.
> The first option breaks if the device names are not persistent.
> The second option can solve the problem#1, but can't solve the problem#2.
> 
> 
> Proposal
> --------
> As multipath command already has a black listing feature, adding
> wwid filtering to it is straightforward solution.  I've created
> a tentative patch as proposal.  (patch for multipath-tools-0.4.3)
> I also think that adding whitelist filtering may be useful.
> 
> 
> Patch (tentative)
> -----------------
> -----------------------------------------------------------------------
> --- multipath-tools-0.4.3/multipath/main.c      2005-03-23 10:18:42.000000000 -0500
> +++ wwidfilter-0.4.3/multipath/main.c     2005-03-28 16:11:51.000000000 -0500
> @@ -746,7 +746,8 @@ coalesce_paths (vector curmp, vector pat
>                 /* skip this path for some reason */
> 
>                 /* 1. if path has no unique id */
> -               if (memcmp(empty_buff, pp1->wwid, WWID_SIZE) == 0)
> +               if ((memcmp(empty_buff, pp1->wwid, WWID_SIZE) == 0) ||
> +                               blacklist(conf->blist, pp1->wwid))
>                         continue;
> 
>                 /* 2. if path already coalesced */
> --- multipath-tools-0.4.3/multipath/dict.c      2005-03-19 07:59:15.000000000 -0500
> +++ wwidfilter-0.4.3/multipath/dict.c     2005-03-28 16:12:40.000000000 -0500
> @@ -249,6 +249,7 @@ init_keywords(void)
> 
>         install_keyword_root("devnode_blacklist", &blacklist_handler);
>         install_keyword("devnode", &devnode_handler);
> +       install_keyword("blackwwid", &devnode_handler);
> 
>         install_keyword_root("devices", &devices_handler);
>         install_keyword("device", &device_handler);
> -----------------------------------------------------------------------
> 
> With above patch, we can filter each devices by specifing multipath.conf
> like following.
> 
> -----------------------------------------------------------------------
> devnode_blacklist {
>         devnode c0d
> 	...
> 	snip
> 	...
>         devnode loop
>         blackwwid SSEAGATE_ST373307LC_____3HZ6XQWB00007431GBM4
>         blackwwid SSEAGATE_ST373307LC_____3HZ70N5S000074343PL8
> }
> -----------------------------------------------------------------------
> 
> 
> Best regards,
> Ky (Kiyoshi Ueda)
> 
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-- 
christophe varoqui <christophe.varoqui at free.fr>