[DRBD-user] Drbd 0.7.12 - Buffer I/O error on device drbd0

Poyner, Brandon bpoyner at ccac.edu
Fri Aug 26 17:39:26 CEST 2005

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

> well, if someone tries to write to the secondary,
> he gets an io error, and the message is "no io allowed".
> if someone tries to read from the secondary, 
> he gets an io error, and the message is "no io allowed".
> where is the problem?

The problem is the assumption that I know what was going on.  It's one
thing if I were trying to mount the device, I could directly see the
relation between my commands and the error.  It's another matter when
that error shows up over night for no obvious reason.  Normally I'd be
left wondering 1) what tried to access the device 2) was the IO request
read or write 3) and is this a serious error?  I don't think the drbd
module would have direct access to #1 (yes/no?).  It should know the
answer to #2, and #3 depends on #1 and #2.  If I only had access to #2 I
could make a more informed decision.

> I can make the message read
> "neither read nor write requests allowed while in secondary mode"
> if you are worried about failing writes,
> watch out for kernel messages like
> "lost page write due to I/O error on <devicename>"
> and similar...

Ok, that's helpful, but I stand by my assertion that clarifying the IO
type would help me figure out the gravity of the situation.

Brandon Poyner
Network Engineer III
CCAC - College Office

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