yum update throws Could not create lock at /var/run/yum.pid on centos 6.5
<p>I have deployed a fresh CentOS 6.5 instance on my VMServer with developement-tools, X11 and few other packages installed. The first day, it seems everythings works fine. Later I couldn't use <strong>yum</strong> installer to update or install any packages and it throws error as follows :</p>

<pre><code>[root@localDev ~]# yum update
Loaded plugins: fastestmirror, refresh-packagekit, security
Cannot open logfile /var/log/yum.log
Could not create lock at /var/run/yum.pid: [Errno 30] Read-only file system: '/var/run/yum.pid'
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  20 M RSS (315 MB VSZ)
    Started: Wed Jul 20 22:01:54 2016 - 00:03 ago
    State  : Running, pid: 10750
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  20 M RSS (315 MB VSZ)
    Started: Wed Jul 20 22:01:54 2016 - 00:05 ago
    State  : Running, pid: 10750
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  20 M RSS (315 MB VSZ)
    Started: Wed Jul 20 22:01:54 2016 - 00:07 ago
    State  : Running, pid: 10750
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  20 M RSS (315 MB VSZ)
    Started: Wed Jul 20 22:01:54 2016 - 00:09 ago
    State  : Running, pid: 10750
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: yum
    Memory :  20 M RSS (315 MB VSZ)
    Started: Wed Jul 20 22:01:54 2016 - 00:11 ago
    State  : Running, pid: 10750
^C

Exiting on user cancel.
[root@localDev ~]#
</code></pre>

<p>Even no such process is running with the mentioned <strong>pid 10750</strong> in the result of ps command.</p>

<pre><code>[root@localDev ~]# ps -eaf
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 Jul19 ?        00:00:00 /sbin/init
root         2     0  0 Jul19 ?        00:00:00 [kthreadd]
root         3     2  0 Jul19 ?        00:00:00 [migration/0]
root         4     2  0 Jul19 ?        00:00:00 [ksoftirqd/0]
root         5     2  0 Jul19 ?        00:00:00 [migration/0]
root         6     2  0 Jul19 ?        00:00:00 [watchdog/0]
root         7     2  0 Jul19 ?        00:00:00 [migration/1]
root         8     2  0 Jul19 ?        00:00:00 [migration/1]
root         9     2  0 Jul19 ?        00:00:00 [ksoftirqd/1]
root        10     2  0 Jul19 ?        00:00:00 [watchdog/1]
root        11     2  0 Jul19 ?        00:00:02 [events/0]
root        12     2  0 Jul19 ?        00:01:03 [events/1]
root        13     2  0 Jul19 ?        00:00:00 [cgroup]
root        14     2  0 Jul19 ?        00:00:00 [khelper]
root        15     2  0 Jul19 ?        00:00:00 [netns]
root        16     2  0 Jul19 ?        00:00:00 [async/mgr]
root        17     2  0 Jul19 ?        00:00:00 [pm]
root        18     2  0 Jul19 ?        00:00:00 [sync_supers]
root        19     2  0 Jul19 ?        00:00:00 [bdi-default]
root        20     2  0 Jul19 ?        00:00:00 [kintegrityd/0]
root        21     2  0 Jul19 ?        00:00:00 [kintegrityd/1]
root        22     2  0 Jul19 ?        00:00:00 [kblockd/0]
root        23     2  0 Jul19 ?        00:00:00 [kblockd/1]
root        24     2  0 Jul19 ?        00:00:00 [kacpid]
root        25     2  0 Jul19 ?        00:00:00 [kacpi_notify]
root        26     2  0 Jul19 ?        00:00:00 [kacpi_hotplug]
root        27     2  0 Jul19 ?        00:00:00 [ata_aux]
root        28     2  0 Jul19 ?        00:00:00 [ata_sff/0]
root        29     2  0 Jul19 ?        00:00:00 [ata_sff/1]
root        30     2  0 Jul19 ?        00:00:00 [ksuspend_usbd]
root        31     2  0 Jul19 ?        00:00:00 [khubd]
root        32     2  0 Jul19 ?        00:00:00 [kseriod]
root        33     2  0 Jul19 ?        00:00:00 [md/0]
root        34     2  0 Jul19 ?        00:00:00 [md/1]
root        35     2  0 Jul19 ?        00:00:00 [md_misc/0]
root        36     2  0 Jul19 ?        00:00:00 [md_misc/1]
root        37     2  0 Jul19 ?        00:00:00 [linkwatch]
root        38     2  0 Jul19 ?        00:00:00 [khungtaskd]
root        39     2  0 Jul19 ?        00:00:00 [kswapd0]
root        40     2  0 Jul19 ?        00:00:00 [ksmd]
root        41     2  0 Jul19 ?        00:00:00 [khugepaged]
root        42     2  0 Jul19 ?        00:00:00 [aio/0]
root        43     2  0 Jul19 ?        00:00:00 [aio/1]
root        44     2  0 Jul19 ?        00:00:00 [crypto/0]
root        45     2  0 Jul19 ?        00:00:00 [crypto/1]
root        50     2  0 Jul19 ?        00:00:00 [kthrotld/0]
root        51     2  0 Jul19 ?        00:00:00 [kthrotld/1]
root        52     2  0 Jul19 ?        00:00:00 [pciehpd]
root        54     2  0 Jul19 ?        00:00:00 [kpsmoused]
root        55     2  0 Jul19 ?        00:00:00 [usbhid_resumer]
root        85     2  0 Jul19 ?        00:00:00 [kstriped]
root       162     2  0 Jul19 ?        00:00:00 [scsi_eh_0]
root       163     2  0 Jul19 ?        00:00:00 [scsi_eh_1]
root       169     2  0 Jul19 ?        00:00:02 [mpt_poll_0]
root       170     2  0 Jul19 ?        00:00:00 [mpt/0]
root       187     2  0 Jul19 ?        00:00:37 [scsi_eh_2]
root       291     2  0 Jul19 ?        00:00:00 [jbd2/sda2-8]
root       292     2  0 Jul19 ?        00:00:00 [ext4-dio-unwrit]
root       381     1  0 Jul19 ?        00:00:00 /sbin/udevd -d
root       564     2  0 Jul19 ?        00:00:02 [vmmemctl]
root       713     2  0 Jul19 ?        00:00:00 [jbd2/sda1-8]
root       714     2  0 Jul19 ?        00:00:00 [ext4-dio-unwrit]
root       715     2  0 Jul19 ?        00:00:00 [jbd2/sda3-8]
root       716     2  0 Jul19 ?        00:00:00 [ext4-dio-unwrit]
root       717     2  0 Jul19 ?        00:00:00 [jbd2/sda6-8]
root       718     2  0 Jul19 ?        00:00:00 [ext4-dio-unwrit]
root       761     2  0 Jul19 ?        00:00:00 [kauditd]
root       995     1  0 Jul19 ?        00:00:00 auditd
root      1020     1  0 Jul19 ?        00:00:01 /sbin/rsyslogd -i /var/run/syslogd.pid -c 5
root      1050     1  0 Jul19 ?        00:00:14 irqbalance --pid=/var/run/irqbalance.pid
rpc       1064     1  0 Jul19 ?        00:00:00 rpcbind
rpcuser   1082     1  0 Jul19 ?        00:00:00 rpc.statd
dbus      1192     1  0 Jul19 ?        00:00:00 dbus-daemon --system
root      1208     1  0 Jul19 ?        00:00:00 cupsd -C /etc/cups/cupsd.conf
root      1233     1  0 Jul19 ?        00:00:00 /usr/sbin/acpid
68        1242     1  0 Jul19 ?        00:00:00 hald
root      1243  1242  0 Jul19 ?        00:00:00 hald-runner
root      1282  1243  0 Jul19 ?        00:00:00 hald-addon-input: Listening on /dev/input/event0 /dev/input/event2
68        1290  1243  0 Jul19 ?        00:00:00 hald-addon-acpi: listening on acpid socket /var/run/acpid.socket
root      1310     1  0 Jul19 ?        00:00:00 automount --pid-file /var/run/autofs.pid
root      1343     1  0 Jul19 ?        00:00:00 /usr/sbin/sshd
postgres  1377     1  0 Jul19 ?        00:00:00 /usr/pgsql-9.2/bin/postmaster -p 5432 -D /var/lib/pgsql/9.2/data
postgres  1379  1377  0 Jul19 ?        00:00:00 postgres: logger process
postgres  1381  1377  0 Jul19 ?        00:00:00 postgres: checkpointer process
postgres  1382  1377  0 Jul19 ?        00:00:00 postgres: writer process
postgres  1383  1377  0 Jul19 ?        00:00:01 postgres: wal writer process
postgres  1384  1377  0 Jul19 ?        00:01:13 postgres: autovacuum launcher process
postgres  1385  1377  0 Jul19 ?        00:00:01 postgres: stats collector process
root      1463     1  0 Jul19 ?        00:00:00 /usr/libexec/postfix/master
postfix   1472  1463  0 Jul19 ?        00:00:00 qmgr -l -t fifo -u
root      1487     1  0 Jul19 ?        00:00:00 /usr/sbin/abrtd
root      1506     1  0 Jul19 ?        00:00:00 /usr/sbin/atd
root      1545     1  0 Jul19 ?        00:00:00 /usr/sbin/certmonger -S -p /var/run/certmonger.pid
root      1558     1  0 Jul19 tty1     00:00:00 /sbin/mingetty /dev/tty1
root      1560     1  0 Jul19 tty2     00:00:00 /sbin/mingetty /dev/tty2
root      1562     1  0 Jul19 tty3     00:00:00 /sbin/mingetty /dev/tty3
root      1564     1  0 Jul19 tty4     00:00:00 /sbin/mingetty /dev/tty4
root      1566     1  0 Jul19 tty5     00:00:00 /sbin/mingetty /dev/tty5
root      1568     1  0 Jul19 tty6     00:00:00 /sbin/mingetty /dev/tty6
root      1569   381  0 Jul19 ?        00:00:00 /sbin/udevd -d
root      1570   381  0 Jul19 ?        00:00:00 /sbin/udevd -d
root     10436  1343  0 19:28 ?        00:00:00 sshd: root@pts/0
root     10438  1343  0 19:28 ?        00:00:00 sshd: root@notty
root     10440 10438  0 19:28 ?        00:00:00 /usr/libexec/openssh/sftp-server
root     10449 10436  0 19:28 pts/0    00:00:00 -bash
postfix  10670  1463  0 21:15 ?        00:00:00 pickup -l -t fifo -u
root     10756     2  0 22:04 ?        00:00:00 [flush-8:0]
root     10765 10449  0 22:09 pts/0    00:00:00 ps -eaf
[root@localDev ~]#
</code></pre>

<p>After some googling and found that the <strong>root partition is mounted as ro</strong> in the setup. Attempted to remount the root partition "/" as rw using the command <code>mount -o remount,rw /</code> which results another error message :</p>

<pre><code>[root@localDev ~]# mount -o remount,rw /
mount: cannot remount block device /dev/sda2 read-write, is write-protected
</code></pre>

<p>Following is the output of command <code>cat /proc/mounts</code> :</p>

<pre><code>[root@localDev ~]# cat /proc/mounts
rootfs / rootfs rw 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,relatime 0 0
devtmpfs /dev devtmpfs rw,relatime,size=1952148k,nr_inodes=488037,mode=755 0 0
devpts /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /dev/shm tmpfs rw,relatime 0 0
/dev/sda2 / ext4 ro,relatime,barrier=1,data=ordered 0 0
/proc/bus/usb /proc/bus/usb usbfs rw,relatime 0 0
/dev/sda1 /boot ext4 rw,relatime,barrier=1,data=ordered 0 0
/dev/sda3 /home ext4 rw,relatime,barrier=1,data=ordered 0 0
/dev/sda6 /tmp ext4 rw,relatime,barrier=1,data=ordered 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0
/etc/auto.misc /misc autofs rw,relatime,fd=7,pgrp=1310,timeout=300,minproto=5,maxproto=5,indirect 0 0
-hosts /net autofs rw,relatime,fd=13,pgrp=1310,timeout=300,minproto=5,maxproto=5,indirect 0 0
cgroup /cgroup/cpuset cgroup rw,relatime,cpuset 0 0
cgroup /cgroup/cpu cgroup rw,relatime,cpu 0 0
cgroup /cgroup/cpuacct cgroup rw,relatime,cpuacct 0 0
cgroup /cgroup/memory cgroup rw,relatime,memory 0 0
cgroup /cgroup/devices cgroup rw,relatime,devices 0 0
cgroup /cgroup/freezer cgroup rw,relatime,freezer 0 0
cgroup /cgroup/net_cls cgroup rw,relatime,net_cls 0 0
cgroup /cgroup/blkio cgroup rw,relatime,blkio 0 0
</code></pre>

<p>What's wrong with this setup? With my little debugging knowledge, tried to modify the mount configuration during booting and results failure. Kindly suggest me a fix to resolve this issue.</p>

<p>Thanks in advance...</p>