[dm-devel] DM Multipath limits

[Martin Wilck]

Hi Lance,


> We ran into a situation yesterday, where it appears there is a limit
> on 
> the number of targets that DM Multipath can use. We are switching to
> a 
> switch/zoning configuration at our office which may present as many
> as 
> 2500 targets to the system. Yesterday, we were testing a smaller
> config, 
> and the limit on the number of targets appears to be 640. When we
> exceed 
> 640, the system locks up. When we try 656 targets, it locks up, then
> if 
> we back out the last 16 targets and replace them with 16 different
> ones, 
> it still locks up. We backed off the zoning for the meantime (which 
> cripples the connection/bandwidth) to about 280 targets, but every 
> filesystem multipaths properly.
> 
> Do you know what is going on, and is there some way to increase this
> limit?

Could you tell what is locking up, the kernel or multipathd? In
general, both the kernel dm-multipath driver and multipath-tools can
handle thousands of paths. You'll need to provide much more detailed
material (log files etc).

Regards,
Martin


-- 
Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)