[dm-devel] [PATCH 2/4] multipath-tools: replace GROUP_BY_SERIAL with MULTIBUS for IBM 3542 and 2105

[Hannes Reinecke]

On 10/03/2016 01:02 PM, Christophe Varoqui wrote:
> Hi Xose,
> 
> Group by serial sure can make sense for hardware not capable of multibus.
> 
> Can you or Hannes (listed as maintainer for IBM) confirm the concerned
> IBM arrays are multibus capable ?
> 
> Best regards,
> Christophe Varoqui
> OpenSVC
> 
> On Thu, Aug 18, 2016 at 7:58 PM, Xose Vazquez Perez
> <xose.vazquez at gmail.com <mailto:xose.vazquez at gmail.com>> wrote:
> 
>     It doesn't make any sense to have, by default, GROUP_BY_SERIAL in
>     real hardware.
> 
>     Cc: Hannes Reinecke <hare at suse.de <mailto:hare at suse.de>>
>     Cc: Christophe Varoqui <christophe.varoqui at opensvc.com
>     <mailto:christophe.varoqui at opensvc.com>>
>     Cc: device-mapper development <dm-devel at redhat.com
>     <mailto:dm-devel at redhat.com>>
>     Signed-off-by: Xose Vazquez Perez <xose.vazquez at gmail.com
>     <mailto:xose.vazquez at gmail.com>>
>     ---
>      libmultipath/hwtable.c | 4 ++--
>      1 file changed, 2 insertions(+), 2 deletions(-)
> 
>     diff --git a/libmultipath/hwtable.c b/libmultipath/hwtable.c
>     index aa3ea9b..72b5e1d 100644
>     --- a/libmultipath/hwtable.c
>     +++ b/libmultipath/hwtable.c
>     @@ -443,7 +443,7 @@ static struct hwentry default_hw[] = {
>                     /* DS4200 / FAStT200 */
>                     .vendor        = "IBM",
>                     .product       = "^3542",
>     -               .pgpolicy      = GROUP_BY_SERIAL,
>     +               .pgpolicy      = MULTIBUS,
>                     .pgfailback    = FAILBACK_UNDEF,
>             },
This is the IBM FAStT 200, which is IIRC an RDAC machine. So multibus
will be wrong here, and it should be using the RDAC entry instead.

>             {
>     @@ -451,7 +451,7 @@ static struct hwentry default_hw[] = {
>                     .vendor        = "IBM",
>                     .product       = "^2105",
>                     .no_path_retry = NO_PATH_RETRY_QUEUE,
>     -               .pgpolicy      = GROUP_BY_SERIAL,
>     +               .pgpolicy      = MULTIBUS,
>                     .pgfailback    = FAILBACK_UNDEF,
>             },
>             {
That's the old IBM ESS 800; this is a fully symmetric active-active
array. So yes, multibus is correct here.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare at suse.de			      +49 911 74053 688
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