[DRBD-user] frequent wrong magic value with kernel >4.9

Lars Ellenberg lars.ellenberg at linbit.com
Tue Jan 9 15:36:34 CET 2018

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

On Mon, Dec 25, 2017 at 03:19:42PM +0100, Andreas Pflug wrote:
> Running two Debian 9.3 machines, directly connected via 10GBit on-board
> X540 10GBit, with 15 drbd devices.
> When running a 4.14.2 kernel (from sid) or a 4.13.13 kernel (from
> stretch-backports), I see several "Wrong magic value 0x4c414245 in
> protocol version 101" per day issued by the secondary, with subsequent
> termination of the connection, reconnect and resync. The magic value
> logged differs, quite often 0x00.
> Using the current 4.9.65 kernel (or older) from stretch didn't show
> these aborts in the past, and after going back they're gone again. It
> seems to be some problem introduced after 4.9 kernels, since both 4.9
> and 4.13 include drbd 8.4.7. Maybe some interference with the nic driver?
> Kernel    drbd   ixgbe     errors
> 4.9.65   8.4.7  4.4.0-k    no
> 4.13.13  8.4.7  5.1.0-k    yes
> 4.14.2   8.4.10 5.1.0-k    yes


What does "lsblk -D" and "lsblk -t" say?

Do you have a scratch volume you can play with?
As a datapoint, you try to "blkdiscard /dev/drbdX" it?
dd if=/dev/zero of=/dev/drbdX bs=1G oflag=direct count=1?

Something like that?
Any "easy" reproducer?

: Lars Ellenberg
: LINBIT | Keeping the Digital World Running
: DRBD -- Heartbeat -- Corosync -- Pacemaker

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