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RE: [dm-devel] [PATCH]:[multipath-tools] Adding the hwtable for LSI generic rdac storage devices



On Fri, 2009-03-06 at 09:38 -0700, Moger, Babu wrote:
> This patch adds the hwtable for LSI rdac generic storage. Also sets the feature pg_init_retries to maximum(50).
> 
> Signed-off-by: Babu Moger <babu moger lsi com>
> 
> ---
> 
> --- multipath-tools/libmultipath/hwtable.c.orig	2009-03-04 14:33:11.000000000 -0600
> +++ multipath-tools/libmultipath/hwtable.c	2009-03-04 14:43:57.000000000 -0600
> @@ -837,6 +837,22 @@ static struct hwentry default_hw[] = {
>  		.checker_name  = RDAC,
>  		.prio_name     = PRIO_RDAC,
>  	},
> +	/* LSI Generic rdac storage */
> +	{
> +		.vendor        = "(LSI|ENGENIO)",
> +		.product       = "INF-01-00",
> +		.getuid        = DEFAULT_GETUID,
> +		.features      = "2 pg_init_retries 50",
> +		.hwhandler     = "1 rdac",
> +		.selector      = DEFAULT_SELECTOR,
> +		.pgpolicy      = GROUP_BY_PRIO,
> +		.pgfailback    = -FAILBACK_IMMEDIATE,
> +		.rr_weight     = RR_WEIGHT_NONE,
> +		.no_path_retry = 15,

you don't want to use "queue" for no path retry ?

No, We did not want to set it to "queue" by default. Reason is, we know that I/O session will hang in case of all path failure. User will not know why the session is non-responsive, if he is not familiar with this feature. Also, we think this feature (queue) is meant for maintenance or support (like replacing the switch/cable or shutting down the storage for short duration).  In these cases user can set to queue on the fly. 

Want to mention one more thing. I saw other hwtable table (mostly IBM). They don't set the feature pg_init_retries. In that case it is defaulting to 0. We have seen issues because of this during the failovers. In case of multi-host scenario (more than one host accessing the same storage), we have seen failovers not been able complete in one attempt and resulting I/O failure. I would suggest setting pg_init_retries to maximum by default. 

> +		.minio         = DEFAULT_MINIO,
> +		.checker_name  = RDAC,
> +		.prio_name     = PRIO_RDAC,
> +	},
>  	/*
>  	 * EOL
>  	 */
> 
> 
> 
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