Can not switch drbd to secondary
I'm running drbd83 with ocfs2 in centos 5 and planning to use packemaker with them.
Afer some time, I'm facing drbd split brain problem.
version: 8.3.13 (api:88/proto:86-96)
GIT-hash: 83ca112086600faacab2f157bc5a9324f7bd7f77 build by [email protected], 2012-05-07 11:56:36
1: cs:StandAlone ro:Primary/Unknown ds:UpToDate/DUnknown r-----
ns:0 nr:0 dw:112281991 dr:797551 al:99 bm:6401 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:60
I can't switch my drbd to secondary.
drbdadm secondary r0
1: State change failed: (-12) Device is held open by someone
Command 'drbdsetup 1 secondary' terminated with exit code 11
My drbd resource config:
resource r0 {
syncer {
rate 1000M;
verify-alg sha1;
}
disk {
on-io-error detach;
}
handlers {
pri-lost-after-sb "/usr/lib/drbd/notify-split-brain.sh root";
}
net {
allow-two-primaries;
after-sb-0pri discard-younger-primary;
after-sb-1pri call-pri-lost-after-sb;
after-sb-2pri call-pri-lost-after-sb;
}
startup { become-primary-on both; }
on serving_4130{
device /dev/drbd1;
disk /dev/sdb1;
address 192.168.4.130:7789;
meta-disk internal;
}
on MT305-3182 {
device /dev/drbd1;
disk /dev/xvdb1;
address 192.168.3.182:7789;
meta-disk internal;
}
}
Status of ocfs2 status:
service ocfs2 status
Configured OCFS2 mountpoints: /data
lsof show that, there is one process relative with drbd.
lsof | grep drbd
COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
drbd1_wor 7782 root cwd DIR 253,0 4096 2 /
drbd1_wor 7782 root rtd DIR 253,0 4096 2 /
drbd1_wor 7782 root txt unknown /proc/7782/exe
And it's a dead symlink:
# ls -l /proc/7782/exe
ls: cannot read symbolic link /proc/7782/exe: No such file or directory
lrwxrwxrwx 1 root root 0 May 4 09:56 /proc/7782/exe
# ps -ef | awk '$2 == "7782" { print $0 }'
root 7782 1 0 Apr22 ? 00:00:20 [drbd1_worker]
Notice that this process is wrapped in square brackets:
man ps:
args COMMAND command with all its arguments as a string. Modifications to the arguments may be shown. The
output in this column may contain spaces. A process marked <defunct> is partly dead, waiting to
be fully destroyed by its parent. Sometimes the process args will be unavailable; when this
happens, ps will instead print the executable name in brackets.
So, the final question is: how can we manually recover DRBD in this case without rebooting?
Reply to @andreask:
My partition table:
# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
35G 6.9G 27G 21% /
/dev/xvda1 99M 20M 74M 22% /boot
tmpfs 1.0G 0 1.0G 0% /dev/shm
/dev/drbd1 100G 902M 100G 1% /data
The device names:
# dmsetup ls --tree -o inverted
(202:2)
├─VolGroup00-LogVol01 (253:1)
└─VolGroup00-LogVol00 (253:0)
Pay attention to the block device (253:0), it is the same as from the output of lsof:
# lvdisplay
--- Logical volume ---
LV Name /dev/VolGroup00/LogVol00
VG Name VolGroup00
LV UUID vCd152-amVZ-GaPo-H9Zs-TIS0-KI6j-ej8kYi
LV Write Access read/write
LV Status available
# open 1
LV Size 35.97 GB
Current LE 1151
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
Reply to @Doug:
# vgdisplay
--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 39.88 GB
PE Size 32.00 MB
Total PE 1276
Alloc PE / Size 1276 / 39.88 GB
Free PE / Size 0 / 0
VG UUID OTwzII-AP5H-nIbH-k2UA-H9nw-juBv-wcvmBq
UPDATE Fri May 17 16:08:16 ICT 2013
Here are some ideas from Lars Ellenberg:
if the filesystem is still mounted ... oh well. unmount it. not lazy, but really.
I'm sure, OCFS2 was already unmounted.
If nfs was involved, try
killall -9 nfsd killall -9 lockd echo 0 > /proc/fs/nfsd/threads
No, NFS was not involved.
if lvm/dmsetup/kpartx/multipath/udev is involved, try
dmsetup ls --tree -o invertedand check if there are dependencies from drbd.
As you can see from my above output, LVM doesn't related to DRBD:
pvdisplay -m
--- Physical volume ---
PV Name /dev/xvda2
VG Name VolGroup00
PV Size 39.90 GB / not usable 20.79 MB
Allocatable yes (but full)
PE Size (KByte) 32768
Total PE 1276
Free PE 0
Allocated PE 1276
PV UUID 1t4hkB-p43c-ABex-stfQ-XaRt-9H4i-51gSTD
--- Physical Segments ---
Physical extent 0 to 1148:
Logical volume /dev/VolGroup00/LogVol00
Logical extents 0 to 1148
Physical extent 1149 to 1275:
Logical volume /dev/VolGroup00/LogVol01
Logical extents 0 to 126
fdisk -l
Disk /dev/xvda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/xvda1 * 1 13 104391 83 Linux
/dev/xvda2 14 5221 41833260 8e Linux LVM
Disk /dev/xvdb: 107.3 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/xvdb1 1 13054 104856223+ 83 Linux
if loop/cryptoloop/etc is involved, check if one of those is still accessing them.
if some virtualization tecknique is in use, shut down/destroy all containers/VMs that may have been accessing that drbd during their life time.
No, it doesn't.
Sometimes it is just udev or equivalent doing a race.
I have disabled the multipath rule and even stop the udevd, and nothing change.
Sometimes it is a unix domain socket or similar still held open (won't necessary show up in lsof/fuser).
If so, how can we find out this unix socket?
UPDATE Wed May 22 22:10:41 ICT 2013
Here is the stacktrace of DRBD worker process when dumping via magic SysRq key:
kernel: drbd1_worker S ffff81007ae21820 0 7782 1 7795 7038 (L-TLB)
kernel: ffff810055d89e00 0000000000000046 000573a8befba2d6 ffffffff8008e82f
kernel: 00078d18577c6114 0000000000000009 ffff81007ae21820 ffff81007fcae040
kernel: 00078d18577ca893 00000000000002b1 ffff81007ae21a08 000000017a590180
kernel: Call Trace:
kernel: [<ffffffff8008e82f>] enqueue_task+0x41/0x56
kernel: [<ffffffff80063002>] thread_return+0x62/0xfe
kernel: [<ffffffff80064905>] __down_interruptible+0xbf/0x112
kernel: [<ffffffff8008ee84>] default_wake_function+0x0/0xe
kernel: [<ffffffff80064713>] __down_failed_interruptible+0x35/0x3a
kernel: [<ffffffff885d461a>] :drbd:.text.lock.drbd_worker+0x2d/0x43
kernel: [<ffffffff885eca37>] :drbd:drbd_thread_setup+0x127/0x1e1
kernel: [<ffffffff800bab82>] audit_syscall_exit+0x329/0x344
kernel: [<ffffffff8005dfb1>] child_rip+0xa/0x11
kernel: [<ffffffff885ec910>] :drbd:drbd_thread_setup+0x0/0x1e1
kernel: [<ffffffff8005dfa7>] child_rip+0x0/0x11
I'm not sure if this OCFS2 heartbeat region is preventing DRBD from switching to secondary:
kernel: o2hb-C3E41CA2 S ffff810002536420 0 9251 31 3690 (L-TLB)
kernel: ffff810004af7d20 0000000000000046 ffff810004af7d30 ffffffff80063002
kernel: 1400000004000000 000000000000000a ffff81007ec307a0 ffffffff80319b60
kernel: 000935c260ad6764 0000000000000fcd ffff81007ec30988 0000000000027e86
kernel: Call Trace:
kernel: [<ffffffff80063002>] thread_return+0x62/0xfe
kernel: [<ffffffff8006389f>] schedule_timeout+0x8a/0xad
kernel: [<ffffffff8009a41d>] process_timeout+0x0/0x5
kernel: [<ffffffff8009a97c>] msleep_interruptible+0x21/0x42
kernel: [<ffffffff884b3b0b>] :ocfs2_nodemanager:o2hb_thread+0xd2c/0x10d6
kernel: [<ffffffff80063002>] thread_return+0x62/0xfe
kernel: [<ffffffff800a329f>] keventd_create_kthread+0x0/0xc4
kernel: [<ffffffff884b2ddf>] :ocfs2_nodemanager:o2hb_thread+0x0/0x10d6
kernel: [<ffffffff800a329f>] keventd_create_kthread+0x0/0xc4
kernel: [<ffffffff80032632>] kthread+0xfe/0x132
kernel: [<ffffffff8005dfb1>] child_rip+0xa/0x11
kernel: [<ffffffff800a329f>] keventd_create_kthread+0x0/0xc4
kernel: [<ffffffff80032534>] kthread+0x0/0x132
kernel: [<ffffffff8005dfa7>] child_rip+0x0/0x11
Solution 1:
I'm not sure if this OCFS2 heartbeat region is preventing DRBD from switching to secondary:
Maybe. Have you tried to kill that region follow this guide?
# /etc/init.d/o2cb offline serving
Stopping O2CB cluster serving: Failed
Unable to stop cluster as heartbeat region still active
OK, firstly you should list the OCFS2 volumes along with their labels and uuids:
# mounted.ocfs2 -d
Device FS Stack UUID Label
/dev/sdb1 ocfs2 o2cb C3E41CA2BDE8477CA7FF2C796098633C data_ocfs2
/dev/drbd1 ocfs2 o2cb C3E41CA2BDE8477CA7FF2C796098633C data_ocfs2
Secondly, check to see if you have any reference to this device:
# ocfs2_hb_ctl -I -d /dev/sdb1
C3E41CA2BDE8477CA7FF2C796098633C: 1 refs
Try to kill it:
# ocfs2_hb_ctl -K -d /dev/sdb1 ocfs2
then stop the cluster stack:
# /etc/init.d/o2cb stop
Stopping O2CB cluster serving: OK
Unmounting ocfs2_dlmfs filesystem: OK
Unloading module "ocfs2_dlmfs": OK
Unmounting configfs filesystem: OK
Unloading module "configfs": OK
and bring the device back into secondary role:
# drbdadm secondary r0
# drbd-overview
1:r0 StandAlone Secondary/Unknown UpToDate/DUnknown r-----
Now you can recover split brain as usual:
# drbdadm -- --discard-my-data connect r0
# drbd-overview
1:r0 WFConnection Secondary/Unknown UpToDate/DUnknown C r-----
On the other node (the split brain survivor):
# drbdadm connect r0
# drbd-overview
1:r0 SyncSource Primary/Secondary UpToDate/Inconsistent C r---- /data ocfs2 100G 1.9G 99G 2%
[>....................] sync'ed: 3.2% (753892/775004)K delay_probe: 28
On the split brain victim:
# /etc/init.d/o2cb start
Loading filesystem "configfs": OK
Mounting configfs filesystem at /sys/kernel/config: OK
Loading filesystem "ocfs2_dlmfs": OK
Mounting ocfs2_dlmfs filesystem at /dlm: OK
Starting O2CB cluster serving: OK
# /etc/init.d/ocfs2 start
Starting Oracle Cluster File System (OCFS2) [ OK ]
Verify that this mount point is up and running:
# df -h /data/
Filesystem Size Used Avail Use% Mounted on
/dev/drbd1 100G 1.9G 99G 2% /data
Solution 2:
A common reason for DRBD being unable to demote a resource is an active device-mapper device ... like a volume group. You can check it e.g. with:
dmsetup ls --tree -o inverted