drbd的source 端
cat /proc/drbd
0: cs:SyncSource ro:Primary/Secondary ds:UpToDate/Inconsistent B r----


drbd的target 端
cat /proc/drbd

0: cs:SyncTarget ro:Secondary/Primary ds:Inconsistent/UpToDate B r----
以上為正常狀況

target斷掉時source會出現
0: cs:WFConnection ro:Primary/Unknown ds:UpToDate/Inconsistent B r----

所以只要捉 cs:SyncSource 這個值來看就可以知道是否正常