Doing an ls gives the following error
ls: reading directory d4_stats/: Input/output error

client error:
[5237686.818045] LustreError: 77522:0:(dir.c:648:ll_readdir()) error reading dir [0x4488b6ced74:0x1edb5:0x0] at 0: rc -5
[5237686.849844] LustreError: 77522:0:(dir.c:648:ll_readdir()) Skipped 51 previous similar messages

MDT Error:
Jan 16 11:18:37 nbp1-mds kernel: Lustre: 15390:0:(mdd_object.c:2412:__mdd_readpage()) build page failed: -5!

Please advise on debug flags to use to gather logs.