[DRBD-user] "kernel: bio too big device drbd0"

[Lutz Vieweg]

On 06/07/2013 02:03 PM, Lars Ellenberg wrote:
>> I also had a look at the latest DRBD 8.4 source. They still mess around
>> with the blk queue limits. Set it larger, set it smaller dynamically
>> while in use depending on the limits on the other node. That's really
>> bad for stacking. So, yes, DRBD caused that issue. No other driver does
>> it like this. A DRBD update can have caused that issue.
>
> Uhm, no.
>
> IF drbd would have made the max bio size smaller while being in use,
> there would have been a log message like
>
>   ASSERT FAILED new < now; (xyz < XYZ)
>   max BIO size = NEW SIZE
>
> Lutz, you see that in your kernel logs?

Yes! - Now that I explicitely searched for such an assertion,
I found one amongst the many harmless drbd status messages,
at the time when the secondary was re-connected after moving
the disk, there:

> 19:56:12 kernel: d-con ResourceData: conn( StandAlone -> Unconnected )
> 19:56:12 kernel: d-con ResourceData: Starting receiver thread (from drbd_w_Resource [2877])
> 19:56:12 kernel: d-con ResourceData: receiver (re)started
> 19:56:12 kernel: d-con ResourceData: conn( Unconnected -> WFConnection )
> 19:56:13 kernel: d-con ResourceData: Handshake successful: Agreed network protocol version 101
> 19:56:13 kernel: d-con ResourceData: conn( WFConnection -> WFReportParams )
> 19:56:13 kernel: d-con ResourceData: Starting asender thread (from drbd_r_Resource [19897])
> 19:56:13 kernel: block drbd0: ASSERT FAILED new < now; (131072 < 1048576)
> 19:56:13 kernel: block drbd0: max BIO size = 131072
> 19:56:13 kernel: block drbd0: drbd_sync_handshake:
> 19:56:13 kernel: block drbd0: self 5809DD75CFABAEC3:90687991BFCD005F:FC1363470657F557:B85F71610F33ECE1 bits:130 flags:0
> 19:56:13 kernel: block drbd0: peer 90687991BFCD005E:0000000000000000:FC1363470657F556:B85F71610F33ECE1 bits:0 flags:0
> 19:56:13 kernel: block drbd0: uuid_compare()=1 by rule 70
> 19:56:13 kernel: block drbd0: peer( Unknown -> Secondary ) conn( WFReportParams -> WFBitMapS ) pdsk( DUnknown -> Consistent )
> 19:56:13 kernel: block drbd0: send bitmap stats [Bytes(packets)]: plain 0(0), RLE 149(1), total 149; compression: 100.0%
> 19:56:13 kernel: block drbd0: receive bitmap stats [Bytes(packets)]: plain 0(0), RLE 149(1), total 149; compression: 100.0%
> 19:56:13 kernel: block drbd0: helper command: /sbin/drbdadm before-resync-source minor-0
> 19:56:13 kernel: block drbd0: helper command: /sbin/drbdadm before-resync-source minor-0 exit code 0 (0x0)
> 19:56:13 kernel: block drbd0: conn( WFBitMapS -> SyncSource ) pdsk( Consistent -> Inconsistent )
> 19:56:13 kernel: block drbd0: updated sync UUID 5809DD75CFABAEC3:90697991BFCD005F:90687991BFCD005F:FC1363470657F557
> 19:56:13 kernel: block drbd0: Began resync as SyncSource (will sync 520 KB [130 bits set]).
> 19:56:14 kernel: block drbd0: Resync done (total 1 sec; paused 0 sec; 520 K/sec)
> 19:56:14 kernel: block drbd0: updated UUIDs 5809DD75CFABAEC3:0000000000000000:90697991BFCD005F:90687991BFCD005F
> 19:56:14 kernel: block drbd0: conn( SyncSource -> Connected ) pdsk( Inconsistent -> UpToDate )

Regards,

Lutz Vieweg