[DRBD-user] How long does it take OOS to clear

[Digimer]

I assumed it wasn't paused, but that confirms it.

Protocol A allows for out of sync to grow. It says "when the data in on
the network buffer to send to the peer, consider the write complete". As
such, data that hasn't made it over to the peer causes oos to climb. If
you have a steady write rate that is faster than your transmit
bandwidth, then seeing fairly steady OOS makes sense.

To "fix" it, you need to increase the connection speed to the peer node.
Or, less likely, if the peer's disk is slower than the bandwidth
connecting it, speed up the disk write speed.

In either case, what you are seeing is not a surprise, and it's not a
problem with DRBD. The only other option is to use protocol C, so that a
write isn't complete until it reaches the peer, but that will slow down
the write performance of the primary node to be whatever speed you have
to the peer. That's likely unacceptable.

In short, you have a hardware/resource issue.

digimer

On 2019-10-21 12:19 p.m., G C wrote:
> version: 8.4.10
> Ran the resume-sync all and received:
> 0: Failure: (135) Sync-pause flag is already cleared
> Command 'drbdsetup-84 resume-sync 0' terminated with exit code 10
> 
> Protocol used is 'A', our systems are running on a cloud environment.
> 
> 
> 
> 
> On Mon, Oct 21, 2019 at 9:09 AM Digimer <lists at alteeve.ca
> <mailto:lists at alteeve.ca>> wrote:
> 
>     8.9.2 is the utils version, what is the kernel module version?
>     (8.3.x/8.4.x/9.0.x)?
> 
>     It's possible something paused sync, but I doubt it. You can try
>     'drbdadm resume-sync all'. The oos number should change constantly, any
>     time a block changes it should go up and every time a block syncs it
>     should go down.
> 
>     What protocol are you using? A, B or C?
> 
>     digimer


-- 
Digimer
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