[OpenIndiana-discuss] sas multipath

[real-men-dont-click at gmx.net]

-----Original message-----
From:	Randy S <sim.ple at live.nl>
Sent:	Wed 06-02-2013 13:03
Subject:	[OpenIndiana-discuss] sas multipath
To:	openindiana-discuss at openindiana.org; 
> 
> Hi all,
> 
> I have a test system running with OIa7, very much ram, 2 LSI SAS 9207-4i4e 
> hba's, 1 sm jbod containing seagate 3Tb sas drives. 
> 
> I have enabled the multipathing with stmsboot and set it to use 
> logical-blocksize, since round-robin symmetric-option isn't functioning.
> 
> During tests I can see that the system sees the two path's  with mpathadm and 
> simple dd tests show that all disks are all accessed at almost maximum speed 
> with minimum latency according to iostat. 
> We started to test with 4 sas disks in 2 striped mirrors. 
> 
> All good, but shouldn't it be possible to pull one of the sas cables without 
> any disruption to the storage, forcing it to use only one path? (this way 
> simulating a broken hba).
> When we do this, the whole system grinds to a screeching halt, being almost 
> unresponsive.
> 
> What am I doing wrong. Maybe somebody can point in in the right direction to 
> troubleshoot.
> 
> Rgrds,
> 
> Randy
> 
> 
> 
> 
> 
>  		 	   		  
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> 

Hi Randy,

we set up sas multipath here with 151a7 (Supermicro JBOD, LSI SAS Controller). We tested failover as well. It worked, almost: after disconnecting one cable everything continued to work, BUT when reconnecting the cable, the system stopped working until rebooted.

We didn't find the reason for this, so far.

If you are laying with MPXIO you might take a look into vhci_stat:
(http://southbrain.com/south/software/vhci-stat.html)


cu

Carsten