Description of problem:
engine-setup should detect if postgresql's shared_buffers are below active kernel.shmmax.

if kernel.shmmax is below what needs postgresql to start it fails. starting the postgresql is part of engine-setup step to create engine database. thus all engine-setup fails and message is little blurry.

OS had  kernel.shmmax=30000000 when executing kernel.shmmax.

[ INFO  ] Creating PostgreSQL database
[ ERROR ] Failed to execute stage 'Misc configuration': Command '/sbin/service' failed to execute
[ INFO  ] Yum Performing yum transaction rollback
[ INFO  ] Stage: Clean up
          Log file is located at /var/log/ovirt-engine/setup/ovirt-engine-setup-20131121134830.log
[ INFO  ] Stage: Pre-termination
[ INFO  ] Stage: Termination
[ ERROR ] Execution of setup failed

* engine-setup:

...snip...
[ INFO  ] Creating PostgreSQL database
[ ERROR ] Failed to execute stage 'Misc configuration': Command '/sbin/service' failed to execute
[ INFO  ] Yum Performing yum transaction rollback
[ INFO  ] Stage: Clean up
          Log file is located at /var/log/ovirt-engine/setup/ovirt-engine-setup-20131121134830.log
[ INFO  ] Stage: Pre-termination
[ INFO  ] Stage: Termination
[ ERROR ] Execution of setup failed

* pgstartup.log

...snip...
LOG:  could not bind IPv6 socket: Cannot assign requested address
HINT:  Is another postmaster already running on port 5432? If not, wait a few seconds and retry.
FATAL:  could not create shared memory segment: Invalid argument
DETAIL:  Failed system call was shmget(key=5432001, size=39280640, 03600).
HINT:  This error usually means that PostgreSQL's request for a shared memory segment exceeded your kernel's SHMMAX parameter.  You can either reduce the reque
st size or reconfigure the kernel with larger SHMMAX.  To reduce the request size (currently 39280640 bytes), reduce PostgreSQL's shared_buffers parameter (cur
rently 4096) and/or its max_connections parameter (currently 153).
        If the request size is already small, it's possible that it is less than your kernel's SHMMIN parameter, in which case raising the request size or reco
nfiguring SHMMIN is called for.
        The PostgreSQL documentation contains more information about shared memory configuration.


Version-Release number of selected component (if applicable):
is24

How reproducible:
100%

Steps to Reproduce:
1. sysctl -w kernel.shmmax=30000000
2. engine-setup
3.

Actual results:
engine-setup fails as postgresql startup fails

Expected results:
either tell user it cannot continue before of low kernel.shmmax value or change it (if possible) on-fly and proceed

Additional info: