OBAS system is rather slow and most tasks execution fails with the standard maintenance page, ie. when trying to resolve Plesk domain conflicts when you click on a domain it takes a lot of time and results in OBAS showing the error page.
OBAS node is running on 64-bit OS and the MySQL instance has been moved to a separate node. CPU load is normal and also vmstat output does not show any particular load or memory issue.
# tail -f /var/log/hspcd/error_log [Sun Nov 2 18:52:21 2014] [error] (12)Cannot allocate memory: fork: Unable to fork new process [Sun Nov 2 18:52:31 2014] [error] (12)Cannot allocate memory: fork: Unable to fork new process
OBAS container memory is insufficient.
Increase SWAP memory of the OBAS container by running the following command on the Virtuozzo node where the contianer is located:
# vzctl set CTID --save --ram 4G --swap 4G
where CTID is the OBAS container number.