Full backup of D drive is getting failed only

Critical bpbrm(pid=243549) from client nc2v04fg01.corp.ukrail.net: FTL - socket write failed     
23/03/2016 18:58:42 - Error bptm(pid=243645) media manager terminated by parent process       
23/03/2016 18:59:59 - Info nc2ibp02(pid=243645) StorageServer=PureDisk:nc2ibp02; Report=PDDO Stats (multi-threaded stream used) for (nc2ibp02): scanned: 62552714 KB, CR sent: 94693 KB, CR sent over FC: 0 KB, dedup: 99.8%, cache hits: 88148 (21.6%), rebased: 226 (0.1%)
23/03/2016 19:00:04 - Error bpbrm(pid=243549) could not send server status message       
23/03/2016 19:00:10 - Info bpbkar(pid=3548) done. status: 24: socket write failed