|PostgreSQL Reference Manual - Volume 3 - Server Administration Guide|
by The PostgreSQL Global Development Group
Paperback (6"x9"), 204 pages
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3.3.1 Server Start-up Failures
There are several common reasons the server might fail to start. Check the server's log file, or start it by hand (without redirecting standard output or standard error) and see what error messages appear. Below we explain some of the most common error messages in more detail.
LOG: could not bind IPv4 socket: Address already in use HINT: Is another postmaster already running on port 5432? If not, wait a few seconds and retry. FATAL: could not create TCP/IP listen socket
This usually means just what it suggests: you tried to start
another server on the same port where one is already running.
However, if the kernel error message is not
already in use or some variant of that, there may
be a different problem. For example, trying to start a server
on a reserved port number may draw something like:
$ postgres -p 666 LOG: could not bind IPv4 socket: Permission denied HINT: Is another postmaster already running on port 666? If not, wait a few seconds and retry. FATAL: could not create TCP/IP listen socket
A message like
FATAL: could not create shared memory segment: Invalid argument DETAIL: Failed system call was shmget(key=5440001, size=4011376640, 03600).
probably means your kernel's limit on the size of shared memory is
smaller than the work area PostgreSQL
is trying to create (4011376640 bytes in this example). Or it could
mean that you do not have System-V-style shared memory support
configured into your kernel at all. As a temporary workaround, you
can try starting the server with a smaller-than-normal number of
shared_buffers). You will eventually want
to reconfigure your kernel to increase the allowed shared memory
size. You may also see this message when trying to start multiple
servers on the same machine, if their total space requested
exceeds the kernel limit.
An error like
FATAL: could not create semaphores: No space left on device DETAIL: Failed system call was semget(5440126, 17, 03600).
does not mean you've run out of disk
space. It means your kernel's limit on the number of
System V semaphores is smaller than the number
PostgreSQL wants to create. As above,
you may be able to work around the problem by starting the
server with a reduced number of allowed connections
max_connections), but you'll eventually want to
increase the kernel limit.
If you get an “illegal system call” error, it is likely that shared memory or semaphores are not supported in your kernel at all. In that case your only option is to reconfigure the kernel to enable these features.
Details about configuring
IPC facilities are given in section 3.4.1 Shared Memory and Semaphores.
|ISBN 0954612043||PostgreSQL Reference Manual - Volume 3 - Server Administration Guide||See the print edition|