RE: [dm-devel] I/O error during path failover

[Edward Goggin <egoggin emc com>]

On Tuesday, November 28, 2006 4:41 AM, Petteri Heinonen wrote:
> To: goggin, edward
> Cc: dm-devel redhat com
> Subject: RE: [dm-devel] I/O error during path failover
> 
> But couple of additional questions. I have tried to specify 
> that additional feature "queue_if_no_path" in several places 
> in multipath.conf, but no matter where I specify it, it does 
> not appear in "multipath -ll" nor "dmsetup table" outputs. Is 
> there some known bug in RHEL4u4 for this?

Try adding the two directives below to the CLARiiON device or
multipath config entries in /etc/multipath.conf.  The combination
of these 2 directives will queue I/O for up to 5 minutes (that
is, 30 times the 10 second polling interval you have configured)
whenever all paths to the block device are failed.

	features		"1 queue_if_no_path"
	no_path_retry	30

> 
> I have also tried to specify parameter no_path_retry with 
> several  different values, but it doesn't change the output 
> of "dmsetup table" in any way. Is this ok?

No.

> I guess that there 
> should be some visible changes in "dmsetup table",

Yes, IFF the queue_if_no_path attribute is enabled, "dmsetup table"
should return the string "1 queue_if_no_path".

> as dm_* 
> kernel modules do not read multipath.conf directly, do they?

No they don't ... only multipathd threads in user space read
/etc/multipath.conf.