[DRBD-user] KAISER healing? Re: Semantics of oos value, verification abortion

[Christoph Lechleitner]

Am 31.12.17 um 17:21 schrieb Christoph Lechleitner:
> On 2017-12-29 23:07, Christoph Lechleitner wrote:
>> On 2017-12-29 00:49, Christoph Lechleitner wrote:
>>
>> What' worse and slightly ALARMING:
>> When this occurs a eventual verification is aborted!
> 
> Maybe it's not that alarming.
> 
> After I failed to find anything in the logfiles of a LXC guest that is
> almost unused but regularily affected I found out those
>   "buffer modified by upper layers during write"
> might be false positives, in swap or append situations.
> 
> While we don't use DRBD for swap, appending to logfiles happens all the
> time.
> 
> I'll follow the recommendation there:
> - switch off data-integrity-alg
> - keep up the regular verify runs

This "works" in the sense that the verify runs now seem to finish (as
opposed to abort).

Although I wouldn't call it "working" as long as certain LXC guest
partitions continue to produce oos-Blocks on a daily basis.

We already have set up an appointment with a kernel expert to find
O_DIRECT "sinners" (by means of the kernel's features for function call
tracing).


BUT, the KAISER/KPTI patches seem to prevent further oos-Blocks.

Or maybe the inconsistencies go undetected now, maybe even hitting the
primary node ;-)

Next update in a few weeks ...


Regards, Christoph