[Dovecot] Error: pipe() failed: Too many open files

[Dirk Essl]

Hi,

I am currently migrating a big bunch of mail accounts to a dovecot 
server running 1.0rc2 on Solaris 10

suddenly all imap processes died and I see this in my dovecot.log:


dovecot: Sep 26 14:54:31 Error: pipe() failed: Too many open files
dovecot: Sep 26 14:54:31 Fatal: dup2(stderr) failed: Bad file number
dovecot: Sep 26 14:54:31 Error: child 29376 (imap) returned error 89
dovecot: Sep 26 15:15:48 Error: pipe() failed: Too many open files
dovecot: Sep 26 15:15:48 Fatal: dup2(stderr) failed: Bad file number
dovecot: Sep 26 15:15:49 Error: child 1563 (imap) returned error 89
dovecot: Sep 26 15:15:55 Error: pipe() failed: Too many open files
dovecot: Sep 26 15:15:55 Fatal: dup2(stderr) failed: Bad file number
dovecot: Sep 26 15:15:55 Error: child 1572 (imap) returned error 89
dovecot: Sep 26 15:15:58 Error: pipe() failed: Too many open files
dovecot: Sep 26 15:15:58 Fatal: dup2(stderr) failed: Bad file number
dovecot: Sep 26 15:15:58 Error: child 1577 (imap) returned error 89
dovecot: Sep 26 15:18:25 Error: pipe() failed: Too many open files
dovecot: Sep 26 15:18:25 Fatal: dup2(stderr) failed: Bad file number
dovecot: Sep 26 15:18:25 Error: child 1659 (imap) returned error 89
dovecot: Sep 26 15:18:27 Error: pipe() failed: Too many open files
dovecot: Sep 26 15:18:27 Fatal: dup2(stderr) failed: Bad file number
dovecot: Sep 26 15:18:27 Error: child 1662 (imap) returned error 89
dovecot: Sep 26 15:18:32 Error: socketpair() failed: Too many open files
dovecot: Sep 26 15:18:32 Error: Temporary failure in creating login 
processes, slowing down for now
dovecot: Sep 26 15:18:32 Error: pipe() failed: Too many open files

what could cause the error? is this from Solaris or from dovecot?

TIA
dirk