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

[Andreas Pflug]

Am 09.01.18 um 16:24 schrieb Lars Ellenberg:
> On Tue, Jan 09, 2018 at 03:36:34PM +0100, Lars Ellenberg wrote:
>> 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
>> "strange".
>>
>> 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?
> Maybe while preparing the pull requests for upstream,
> we missed/mangled/broke something.
>
> Can you also reproduce with "out-of-tree" drbd 8.4.10?
>
So I have currently kernel 4.9.65 with drbd 8.3.7 on the primary server,
with the second server (4.14.7 with drbd 8.3.11-rc1) having all drbd
devices secondary.

Llogged in kern.log on the secondary:
Jan 15 15:13:22 xen2 kernel: [451977.741177] drbd monitor.opt: Wrong
magic value 0x64656772 in protocol version 101


Regards

Andreas