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

Poyner, Brandon bpoyner at ccac.edu
Fri Aug 26 16:44:33 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.

> > To me I/O can mean read or write.  Could the error message 
> > be made a bit more clear that a read request is being made?
> > It's worth panicing if I see a drbd write error on the 
> > secondary.  Perhaps something like this.
> definetely not. IO means read _and_ write. both are not allowed.

Unless I'm mistaken an I/O request can either be read or 
write to a single device with single channel access, but not 
both read and write _at the same time_.  Are we talking about 
completely different things?  All I'm really saying is that 
logging 'no IO requests allowed' doesn't tell me if the I/O 
request was read or write.  Many system utilities open the 
device read only to try to probe it, and that's not such a 
worry when done read only.  As you say both modes aren't 
allowed and that's fine, but the difference seems significant to me.

> if you see this message, it is some application trying to access
> /dev/drbd while it is in secondary state.
> this message is never logged for drbd internal requests, 
> those go to the lower level device, and if such io fails, 
> depending on your config, a detach or panic will follow... 
> you for sure will notice.
I follow you here.  
Brandon Poyner
Network Engineer III
CCAC - College Office

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