We are using DB version 5.1.19 on RHEL 6.3, with these patches:
# Intends to solve locked sync
patch -Np0 <../21036_5.1.19_1.diff
# Intends to solve PANIC: log sequence error by replication aware logging
patch -p0 <../20342_5.1.19_1.diff
# Intends to solve haging passive
patch -Np0 <../21326_5.1.19_msghang2.diff
# Intends to solve PANIC: unpinned page
patch -Np1 <../19130-5.1.19.diff
# Intends to fix patch 20342_5.1.19_1.diff: log files not removed
patch -Np0 < ../21448_5.1.19.diff
# Intends to add repmg queue limit and statistics.
# In this patch, we modified the IN_QUEUE_LIMIT_BULK from 1000 to 100000
patch -p0 < ../21420_5.1.19sv_3.diff
# Intends to solve PANIC: file size not a multiple of the page size
patch -p0 < ../21254_5.1.19.diff
# Intends to improve performance by more accurate locks
patch -p0 < ../21454_5.1.19_prelim3.diff
# The patch to fix DB_NOTFOUND panic during initial synch process
# NOTE. This patch is incompatible with the diagnosic 21314_5.1.19_repdiag3.diff patch.
# the diagnostic patch 22451_5.1.19_repdiag4.diff must be used instead of 21314_5.1.19_repdiag3.diff
# if 20668_5.1.19_1.diff is applied.
patch -p0 <../20668_5.1.19_1.diff