[DRBD-user] Secondary node io-error

Lars Ellenberg lars.ellenberg at linbit.com
Tue Oct 16 13:35:33 CEST 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On Thu, Oct 11, 2012 at 02:01:43AM +0000, Velayutham, Prakash wrote:
> >> As you can see, there is absolutely nothing there to suggest that the
> >> secondary even noticed the io-error.
> >> 
> >> I can't understand what is going on.
> > 
> > Do you realize that you need to do IO to get (and then be able to notice) IO errors?

> I just got confused because the primary node got fenced right away
> without any sort of manual write operation from me,
> but the secondary did not exhibit that same behavior.

Usually, to deliver best latency, we READ from local disk (as long as
that is present and "UpToDate").
Though, with 8.4, you can chose to "load balance" READ.

Probably "something" did some READ IO,
maybe udev called blkid, which reads some blocks,
and those would not be seen or serviced on the Secondary,
but only on the Primary.

Cheers,

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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