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Re: [dm-devel] 2.6.2-udm2



On Wednesday 18 February 2004 10:47, Joe Thornber wrote:
> On Wed, Feb 18, 2004 at 10:34:19AM -0600, Kevin Corry wrote:
> > Of course, suspending the device for that long a period is probably not
> > wise to begin with, depending on the activity on that device. Suspends
> > are generally meant to be very short. Pre-load the new device table,
> > suspend the device, switch in the new table, resume the device.
>
> It's not just about keeping the suspend period short, the preloading
> of a table is the bit that requires memory allocations.

Yes, but in the example Patrick mentioned, there wouldn't be any new table to 
load (assuming when the cable is switched it doesn't suddenly show up as a 
different device). It would simply be a suspend followed by a resume, with 
the intention of preventing mpath from detecting I/O errors.

My point was that suspending a device for the length of time needed to 
physically change a cable could lead to memory starvation.

In any case, I'm not a big fan of queueing I/Os or suspending the device when 
all the paths in an mpath device fail. It just seems like it's going to cause 
more problems than it's going to solve.

-- 
Kevin Corry
kevcorry us ibm com
http://evms.sourceforge.net/



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