I have a pair of Syslog-NG servers running 3.2.5-3. The hardware specs are - Quad Xeon E5-2680 (32 cores), 32GB RAM, and two 1TB SAS 7200 RPM disks in RAID-1. OS is RHEL6.2 - Kernel 2.6.32-279.5.2. Filesystem is ext3. Global options are set as: options { flush_lines (1000); time_reopen (10); log_fifo_size (1000); long_hostnames (off); use_dns (no); use_fqdn (no); create_dirs (yes); keep_hostname (yes); keep_timestamp(yes); dir_group("syslog"); perm(0640); dir_perm(0750); group("syslog"); }; I have already set TCP kernel buffers to 128MB max and set disk scheduler to "deadline". But even under light disk IO load, from ~8-25MB, I see "1320811067 packets collapsed in receive queue due to low socket buffer". I had some other processes on the host writing to disk. Stopping them reduced the packet errors but this number still keeps incrementing. To rule out other issues, I temporarily pointed my disk-based destinations to /dev/null and then packet losses/errors stopped. So either Syslog-NG isn't able to write to disk fast enough or there is an underlying OS/hardware issue. Both hosts have the same issue. Any pointers in troubleshooting it will be appreciated. TIA.