A more verbose version of /proc/drbd does exist. Here is how you enable it.
Level 0 (default)
[root@cent7a ~]# echo 0 > /sys/module/drbd/parameters/proc_details
[root@cent7a ~]# cat /proc/drbd
version: 8.4.12-1 (api:1/proto:86-101)
GIT-hash: 92ebfa800c157f488744bf5b13e40e1787b818cd build by @buildsystem, 2020-10-01 13:29:21
0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
ns:102400 nr:0 dw:102400 dr:3156 al:25 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0
Level 1
[root@cent7a ~]# echo 1 > /sys/module/drbd/parameters/proc_details
[root@cent7a ~]# cat /proc/drbd
version: 8.4.12-1 (api:1/proto:86-101)
GIT-hash: 92ebfa800c157f488744bf5b13e40e1787b818cd build by @buildsystem, 2020-10-01 13:29:21
0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
ns:102400 nr:0 dw:102400 dr:3156 al:25 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0
resync: used:0/61 hits:0 misses:0 starving:0 locked:0 changed:0
act_log: used:0/1237 hits:175 misses:125 starving:0 locked:0 changed:25
Level 2
[root@cent7a ~]# echo 2 > /sys/module/drbd/parameters/proc_details
[root@cent7a ~]# cat /proc/drbd
version: 8.4.12-1 (api:1/proto:86-101)
GIT-hash: 92ebfa800c157f488744bf5b13e40e1787b818cd build by @buildsystem, 2020-10-01 13:29:21
0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
ns:102400 nr:0 dw:102400 dr:3156 al:25 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0
resync: used:0/61 hits:0 misses:0 starving:0 locked:0 changed:0
act_log: used:0/1237 hits:175 misses:125 starving:0 locked:0 changed:25
blocked on activity log: 0
Notes:
A brief explanation of some of the additional fields this provides.
The resync hits and misses counters are related to the "resync extents" which
is how DRBD® locks regions for resync to avoid confusion with concurrent application writes.
I can't think of a situation where they would ever be useful to anyone except for LINBIT®
developers. The act_log hits/misses are referring to how many written blocks have been a
part of the blocks that make up the activity log versus anywhere outside of it.
Again, not information that is useful to end users, and we have removed "/proc/drbd" from
DRBD 9 for these reasons.
Edited on 2021/12/14 - DJV