How to remount filesystem in read write mode under Linux

Most of the time on newly created file systems of NFS filesystems we see error like below :

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root@kerneltalks # touch file1

touch: cannot touch ‘file1’: Read-only file system

This is because file system is mounted as read only. In such scenario you have to mount it in read-write mode. Before that we will see how to check if file system is mounted in read only mode and then we will get to how to re mount it as a read write filesystem.

How to check if file system is read only

To confirm file system is mounted in read only mode use below command –

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# cat /proc/mounts | grep datastore

/dev/xvdf /datastore ext3 ro,seclabel,relatime,data=ordered 0 0

Grep your mount point in cat /proc/mounts and observer third column which shows all options which are used in mounted file system. Here ro denotes file system is mounted read-only.

You can also get these details using mount -v command

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root@kerneltalks # mount -v |grep datastore

/dev/xvdf on /datastore type ext3 (ro,relatime,seclabel,data=ordered)

In this output. file system options are listed in braces at last column.

Re-mount file system in read-write mode

To remount file system in read-write mode use below command –

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root@kerneltalks # mount -o remount,rw /datastore

root@kerneltalks # mount -v |grep datastore

/dev/xvdf on /datastore type ext3 (rw,relatime,seclabel,data=ordered)

Observe after re-mounting option ro changed to rw. Now, file system is mounted as read write and now you can write files in it.

Note : It is recommended to fsck file system before re mounting it.

You can check file system by running fsck on its volume.

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root@kerneltalks # df -h /datastore

Filesystem      Size  Used Avail Use% Mounted on

/dev/xvda2       10G  881M  9.2G   9% /

root@kerneltalks # fsck /dev/xvdf

fsck from util-linux 2.23.2

e2fsck 1.42.9 (28-Dec-2013)

/dev/xvdf: clean, 12/655360 files, 79696/2621440 blocks

Sometimes there are some corrections needs to be made on file system which needs reboot to make sure there are no processes are accessing file system.