Snapshots in RHEL 4 are broken. We've had to move to veritas after Redhat told us that they would not support snapshots in RHEL 4. Satoshi Nagayasu wrote: > Hi all, > > I'm testing PostgreSQL(RDBMS) backup using LVM2 snapshot on RHEL4. > > After creating a snapshot, some processes (kjournald, > one PostgreSQL backend and others) go to iowait status, > and they never come back. (see pid 8105 and 2973 in below) > > In this situation, one PostgreSQL backend process is waiting > in COMMIT processing(it generates fsync() on logical volume), > and also kjournald is waiting something. > > There is no kernel oops, and the processors are not used. > > When I set an PostgreSQL option not to generate fsync > on COMMIT, it looks work well. No process hangs. > > I guess some race conditions is occured around kjournald. > > Any comments and suggestions? > > Thanks. > ------------------------------------ > # uname -a > Linux st17 2.6.9-5.ELsmp #1 SMP Wed Jan 5 19:30:39 EST 2005 i686 i686 i386 GNU/Linux > # df > Filesystem 1K-blocks Used Available Use% Mounted on > /dev/sda5 20161172 6717648 12419384 36% / > /dev/sda1 202219 11423 180356 6% /boot > none 1037448 0 1037448 0% /dev/shm > /dev/mapper/vg0-pgdata > 1032088 515532 464128 53% /pgdata > # ps ax > PID TTY STAT TIME COMMAND > 1 ? S 0:00 init [3] > 2 ? S 0:00 [migration/0] > 3 ? SN 0:00 [ksoftirqd/0] > 4 ? S 0:00 [migration/1] > 5 ? SN 0:00 [ksoftirqd/1] > 6 ? S< 0:00 [events/0] > 7 ? S< 0:00 [events/1] > 8 ? S< 0:00 [khelper] > 9 ? S< 0:00 [kacpid] > 30 ? S< 0:00 [kblockd/0] > 31 ? S< 0:00 [kblockd/1] > 44 ? S< 0:00 [aio/0] > 45 ? S< 0:00 [aio/1] > 32 ? S 0:00 [khubd] > 43 ? S 0:11 [kswapd0] > 118 ? S 0:00 [kseriod] > 186 ? S 0:00 [scsi_eh_0] > 201 ? S 0:17 [kjournald] > 1157 ? S<s 0:00 udevd > 1342 ? S 0:00 [kjournald] > 1761 ? Ss 0:00 syslogd -m 0 > 1765 ? Ss 0:00 klogd -x > 1776 ? Ss 0:00 irqbalance > 1794 ? Ss 0:00 portmap > 1814 ? Ss 0:00 rpc.statd > 1913 ? Ss 0:00 rpc.idmapd > 1990 ? Ss 0:00 /usr/sbin/acpid > 2003 ? Ss 0:00 cupsd > 2042 ? Ss 0:00 /usr/sbin/sshd > 2116 ? Ss 0:00 xinetd -stayalive -pidfile /var/run/xinetd.pid > 2126 ? Ss 0:00 gpm -m /dev/input/mice -t imps2 > 2169 ? Ss 0:00 /usr/sbin/htt -retryonerror 0 > 2170 ? S 0:00 htt_server -nodaemon > 2182 ? Ss 0:00 /usr/sbin/cannaserver -syslog -u canna > 2233 ? Ss 0:00 crond > 2274 ? Ss 0:00 xfs -droppriv -daemon > 2293 ? Ss 0:00 /usr/sbin/atd > 2303 ? Ssl 0:00 dbus-daemon-1 --system > 2317 ? Ss 0:00 cups-config-daemon > 2328 ? Ss 0:01 hald > 2338 tty1 Ss+ 0:00 /sbin/mingetty tty1 > 2339 tty2 Ss+ 0:00 /sbin/mingetty tty2 > 2340 tty3 Ss+ 0:00 /sbin/mingetty tty3 > 2341 tty4 Ss+ 0:00 /sbin/mingetty tty4 > 2342 tty5 Ss+ 0:00 /sbin/mingetty tty5 > 2343 tty6 Ss+ 0:00 /sbin/mingetty tty6 > 2885 ? Ss 0:00 sshd: snaga [priv] > 2887 ? S 0:00 sshd: snaga@pts/0 > 2888 pts/0 Ss 0:00 -bash > 2908 ? Ss 0:00 sshd: snaga [priv] > 2910 ? S 0:00 sshd: snaga@pts/1 > 2911 pts/1 Ss 0:00 -bash > 2931 pts/1 S 0:00 su > 2932 pts/1 S 0:00 bash > 2973 ? D 0:31 [kjournald] > 2980 ? S 0:54 [rpciod] > 2981 ? S 0:00 [lockd] > 3016 pts/0 S 0:00 su > 3017 pts/0 S 0:00 bash > 3035 pts/0 S 0:00 su postgres > 3036 pts/0 S 0:00 bash > 7866 pts/0 S+ 0:00 /bin/sh ./pgbench_lvm.sh > 7906 pts/0 S+ 0:00 /bin/sh ./pgbench_lvm.sh > 7907 pts/0 S+ 0:00 sed -e s/^/lvm:/ > 7915 pts/0 S+ 0:00 /usr/local/pgsql81b3/bin/postmaster -D /pgdata/data > 7917 pts/0 S+ 0:03 postgres: writer process > 7918 pts/0 S+ 0:00 postgres: archiver process > 7919 pts/0 S+ 0:00 postgres: stats buffer process > 7920 pts/0 S+ 0:00 postgres: stats collector process > 8015 ? S 0:01 [pdflush] > 8094 pts/0 S+ 0:01 pgbench -s 10 -t 1000 -c 16 pgbench > 8096 pts/0 S+ 0:00 postgres: postgres pgbench [local] COMMIT > 8097 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8098 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8099 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8100 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8101 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8102 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8103 pts/0 S+ 0:00 postgres: postgres pgbench [local] COMMIT > 8104 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8105 pts/0 D+ 0:00 postgres: postgres pgbench [local] COMMIT > 8106 pts/0 S+ 0:00 postgres: postgres pgbench [local] COMMIT > 8107 pts/0 S+ 0:00 postgres: postgres pgbench [local] COMMIT > 8108 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8109 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8110 pts/0 S+ 0:00 postgres: postgres pgbench [local] UPDATE waiting > 8111 pts/0 S+ 0:00 postgres: postgres pgbench [local] COMMIT > 8119 ? S 0:00 [pdflush] > 8147 ? S< 0:00 [kcopyd] > 8179 ? S 0:00 [kjournald] > 8188 pts/1 R+ 0:00 ps ax > # cat /etc/issue > Red Hat Enterprise Linux ES release 4 (Nahant) > Kernel \r on an \m > > # > ------------------------------------ > _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
