Archivel process hungs and kill the sessions.

hi experts,
In our three node RAC database.  Archival hangs while creating arch file for seq#2227.
 There are two arch logs generated for seq#2227
 
  % l /isdprod/isddrop_fra/ISDDROP/archivelog/2011_12_30/o1_mf_1_2227_*
  -rw-rw---- 1 arudba arudba 46805504 Dec 30 18:12
  /isdprod/isddrop_fra/ISDDROP/archivelog/2011_12_30/o1_mf_1_2227_7hwvvmkl_.arc
  -rw-rw---- 1 arudba arudba 46805504 Dec 30 18:18
/isdprod/isddrop_fra/ISDDROP/archivelog/2011_12_30/o1_mf_1_2227_7hww72oy_.arc
 
 
  1. Error reported in alert @ Fri Dec 30 18:12:16 PST 2011
 
  ORA-19504: failed to create file
  "/isdprod/isddrop_fra/ISDDROP/archivelog/2011_12_30/o1_mf_1_2227_%u_.arc"
  ORA-27086: unable to lock file - already in use
  Linux-x86_64 Error: 4: Interrupted system call
 
  At that time there was arch file created on OS with timestamps Dec 30 18:12