Return-Path: owner-postman Received: from localhost (localhost [127.0.0.1]) by nobozo.CS.Berkeley.EDU (8.6.4/8.6.3) with SMTP id NAA23484 for postgres-dist; Mon, 28 Mar 1994 13:43:18 -0800 Resent-From: POSTGRES mailing list Resent-Message-Id: <199403282143.NAA23484@nobozo.CS.Berkeley.EDU> Sender: owner-postman@postgres.Berkeley.EDU X-Return-Path: owner-postman Received: from faerie.CS.Berkeley.EDU (faerie.CS.Berkeley.EDU [128.32.149.14]) by nobozo.CS.Berkeley.EDU (8.6.4/8.6.3) with ESMTP id NAA23475 for ; Mon, 28 Mar 1994 13:43:17 -0800 Received: from localhost (localhost [127.0.0.1]) by faerie.CS.Berkeley.EDU (8.6.4/8.1B) with SMTP id NAA27909; Mon, 28 Mar 1994 13:43:15 -0800 Message-Id: <199403282143.NAA27909@faerie.CS.Berkeley.EDU> X-Authentication-Warning: faerie.CS.Berkeley.EDU: Host localhost didn't use HELO protocol From: aoki@postgres.Berkeley.EDU (Paul M. Aoki) To: postgres@postgres.Berkeley.EDU Subject: Re: postgres & root Reply-To: aoki@postgres.Berkeley.EDU (Paul M. Aoki) In-reply-to: Your message of Mon, 28 Mar 1994 10:26:21 -0800 <199403281826.KAA23468@newberry.uoregon.edu> Date: Mon, 28 Mar 94 13:43:14 -0800 X-Sender: aoki@postgres.Berkeley.EDU Resent-To: postgres-dist@postgres.Berkeley.EDU X-Mts: smtp Resent-Date: Mon, 28 Mar 94 13:43:18 -0800 Resent-XMts: smtp a system administrator writes: > I'm the guilty party Ken Dueker at U of Oregon implied to you for running > postmaster under root - Postmaster fails to get shared memory allocated when > running as postgres. error message is IpcMemoryAttach: shmat failed: permis sion > denied. i don't know offhand, but the following can cause a problem with the same symptoms: > faerie:postgres (142)> whoami > postgres > faerie:postgres (143)> ipcs > > IPC status from /dev/kmem as of Mon Mar 28 21:22:04 1994 > Message Queues: > T ID KEY MODE OWNER GROUP > *** No message queues are currently defined *** > > Shared Memory > T ID KEY MODE OWNER GROUP > m 0 0 D-rw------- root system > m 1 0 D-rw------- root system > m 2 0 D-rw------- root system > m 803 123585129 --rw------- aoki postgres > m 804 123585135 --rw------- aoki postgres > > Semaphores > T ID KEY MODE OWNER GROUP > s 280 123585139 --ra------- aoki postgres > s 281 123585140 --ra------- aoki postgres > s 282 123585141 --ra------- aoki postgres [segments owned by aoki are left over from a dead postmaster] > faerie:postgres (144)> postmaster > IpcMemoryAttach: shmat() failed: Permission denied > faerie:postgres (145)> that is, say someone once tried to start a postmaster on a given port as user , which crashed without releasing its shared memory segments. if you then try to start a postmaster as user on the *same port*, the postmaster will try to create a new segment with the same key (the key is derived from the port number). shmget(2) says, "great, there's already a segment with that key, here's the shmid for it," but when the postmaster tries to *attach* with shmat(2), shmat says, "bogus! this segment doesn't belong to you -- hasta luego." (it actually says EACCES but that's my translation into kowfornian.) you don't get the usual "two postmasters on one port" message: > FATAL: StreamServerPort: bind() failed: errno=13 > Is another postmaster already running on that port? > If not, wait a few seconds and retry. > postmaster: cannot create stream port because the other postmaster is dead and not occupying the port. (it is also possible but less likely that some other random process just happens to have a segment with the same shared memory key. in either case, however, ipcs reveals all.) if this is the problem, it ought to go away if you blow away the dead shmem segments (using ipcrm) or reboot the machine. (to prevent a different set of problems, make sure the binaries aren't setuid.) -- Paul M. Aoki | CS Div., Dept. of EECS, UCB | aoki@postgres.Berkeley.EDU | Berkeley, CA 94720 | ...!uunet!ucbvax!aoki