[DRBD-user] disable-write-same in DRBD 8.4.10

[Jean-Francois Malouin]

Hi,

drbd 8.4.10
drbd-utils 9.5.0-1
kernel 4.19.0-6-amd64
on Debian/Buster.

I have a nested LVM setup using DRBD and I have seen quite a lot of
disconnects between
primary and secondary and I wonder if it is safe or correct or even related to
set 'disable-write-same yes;' in view of [*] -- I have Xen VMs as volume groups
living on top of DRBD.

My resources all have the default value 'disable-write-same no;'
in the disk section when I do 'drbdsetup show rX --show-defaults'.
However all disk devices on both peers have:

grep ^ /sys/block/*/device/scsi_disk/*/max_write_same_blocks
/sys/block/sda/device/scsi_disk/0:0:0:0/max_write_same_blocks:0
/sys/block/sdb/device/scsi_disk/1:0:0:0/max_write_same_blocks:0
/sys/block/sdc/device/scsi_disk/2:0:0:0/max_write_same_blocks:0
/sys/block/sdd/device/scsi_disk/3:0:0:0/max_write_same_blocks:0

so it looks like the have write-same disabled.


[*] https://lists.linbit.com/pipermail/drbd-user/2017-January/022931.html

thanks,
jf