Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi, I'm testing DRBD on a couple of virtual machines running Debian Jessie, and noticed that every time a discard request is sent to the DRBD-device, the secondary DRBD host becomes diskless: > [ 121.779367] block drbd2: discard: error=-95 s=0s > [ 121.779376] block drbd2: disk( UpToDate -> Failed ) > [ 121.779382] block drbd2: Local IO failed in drbd_endio_write_sec_final. Detaching... > [ 121.779866] block drbd2: bitmap WRITE of 0 pages took 0 jiffies > [ 121.779873] block drbd2: 0 KB (0 bits) marked out-of-sync by on disk bit-map. > [ 121.779877] block drbd2: disk( Failed -> Diskless ) The backing device for the DRBD-devices is a thin-provisioned LVM2 volume, created using: > lvcreate -L 2G -T vg/dvb-testvm-01 lvdisplay for the lvm-volume is available here: https://gist.github.com/olavmrk/de339e697b0be1ad5d19#file-lvdisplay This is a stock Debian Jessie install, using kernel version 3.16.7-ckt11-1. My drbd disk configuration: https://gist.github.com/olavmrk/de339e697b0be1ad5d19#file-testvm-01-res In my case, the discard happened as I was creating a file system on the DRBD-device: > mkfs.ext4 /dev/drbd/by-res/testvm-01 I was also able to reproduce by running blkdiscard: > blkdiscard /dev/drbd/by-res/testvm-01 error -95 seems to be -EOPNOTSUPP, which makes sense, since I have not made any effort in trying to support TRIM through the virtual machine. I assume that I am hitting this code path: https://github.com/torvalds/linux/blob/v4.3-rc4/drivers/block/drbd/drbd_worker.c#L151 The same error seems to be dealt with when it happens on the primary: https://github.com/torvalds/linux/blob/v4.3-rc4/drivers/block/drbd/drbd_worker.c#L246 https://github.com/torvalds/linux/blob/v4.3-rc4/drivers/block/drbd/drbd_req.c#L651 I tried searching for this problem but couldn't find any mentions of it. I can't be the only one running DRBD on volumes that do not support the TRIM/discard operation, so I am wondering if anybody has any ideas about what actually triggers this bug on my setup? Best regards, Olav Morken