rsync /somedir work@backups::somearchive/ gets stuck in huge maildirs, rsync /somedir root@backups:/some/path/ works

Herwig Wittmann hw at
Mon Dec 11 19:12:56 GMT 2006


i hope i'm not reporting something well-known; i tried to
understand the available bug tracking information. please excuse
me if my problem report should not meet your standards, but i
want to direct your attention to the following:


        problem report for rsync 2.6.9 on linux/IA32, 09 Dec 2006
                 Herwig Wittmann - Initials At Geizhals .at

         "chrooted rsync gets stuck in huge maildirs, retval 12"

(i'm not sure wheter an chroot() mechanism is invoked in my case,
or not, please see the mentioned URI which contains the used rsync.conf)

*) it seems that rsync runs using the chroot mechanism get stuck
    reproduceably and time out with return value 12 in Maildirs
    with > 60 000 (mostly small) files
    (at least when the transfer runs over a line with limited bandwith)

*) rsync runs started as superuser, without use of the chroot mechanism
    seem to work over the same line

*) the 16 Mbit/s line used for the rsync transfer was monitored
    continuously during the transfer with a running "ping", there was no
    packet loss and > 95% of the round trip times were < 20ms

*) + rsync 2.6.9 on linux/IA32 was used;
    + i have read
    + there should have been plenty of free disk space on both hosts
    + continuous monitoring did not show any network errors
    + i do not want to supply the generated core dump for security
      reasons, as there might be information disclosure problems

debug run, all mentioned files can be found in

1) at 15:39, rsync was started as a daemon on host "backup":
backup:~# date
Sat Dec  9 15:39:45 CET 2006
backup:~# strace -ff -o rsyncdaemon.strace rsync --daemon --no-detach \
                  --port 5678  --config /etc/rsyncd.conf 2>rsync.out

this later generated the following files on rsync daemon host "backup":
-rw-r--r--  1 root root     5596 Dec  9 15:40 rsyncdaemon.strace
-rw-r--r--  1 root root 26039248 Dec  9 15:43 rsyncdaemon.strace.13629
-rw-r--r--  1 root root   960396 Dec  9 15:43 rsyncdaemon.strace.13682

2) at 15:40, i started the rsync client on rsyncclient host "morework":
strace -ff -o rsyncclient.strace rsync --rsync-path=/root/rsync-debug \
       --port 5678\
       --timeout=600 -avz --numeric-ids --delete \
       --password-file=/etc/ \
       /home/xxy work at backups::work/home/xxy/ \
       2> /root/rsyncdebug.err >> /root/rsyncdebug.out

this later generated the following files on rsyncclient host "morework":
-rw-r--r-- 1 root root 70955672 Dec  9 15:46 rsyncclient.strace
-rw-r--r-- 1 root root      256 Dec  9 15:46 rsyncdebug.err
-rw-r--r-- 1 root root    34200 Dec  9 15:42 rsyncdebug.out

3) at 15:42, rsync transferred the last file, then both sides start
to wait indefinitely in select() system calls. i waited for two more
minutes and then

4) at 15:44, i invoked on the client host:
morework:~# netstat > netstat-clienthost.txt

5) at 15:44, i invoked on the daemon host:
backup:~# netstat > netstat-daemonhost.txt
backup:~# kill -SEGV 13682; mv core core.13682
mv: cannot stat `core': No such file or directory
# okay, seems this did not generate a core dump for some reason
backup:~# kill -SEGV 13629 # no core dump either
backup:~# killall -SEGV rsync    # <<-- but this generated a core file:
-rw------- 1 root root   364544 Dec  9 15:54 core

Best regards,

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