After a system crash, my centOS server has been rebooted. Now I would like to copy several files but, whatever cp I try on those same files I could regularly copy before the crash, I keep getting an error message saying

cp: cannot create regular file `xxx': Read-only file system

How can I get rid of this error and be able again of creating copies of my files?

Thanks for your help

It looks like whatever you're trying to write to has been mounted as read-only. You'll need to umount it, and mount it again without readonly set. You may also want to run an fsck on your filesystem, check your /etc/stab, reboot, etc.

Try to umount and mount it again in read write. However, note that Linux mount filesystems in read only automatically in some cases, as in example after i/o errors while accessing to the disks.

Thanks for your suggestions. I'm ready to unmount and remount it but, being a real linux newbie, I need step-by-step instructions on how to do that. Would you be so kind to send me the exact sequence of commands that will allow me to unmount and remount my filesystem in read/write? Thanks in advance.

By default, local filesystems are mounted in rw mode, so you only have to umount and mount it with default options.

1. Find out the mountpoint. Let's think I receive the error in directory /data/dir1. I execute:

df /data/dir1

You'll find something like:

/dev/something 937372 494028 443344 53% /data

2. Check filesystem is in fstab file:

grep data /etc/fstab

There should be a line for /data, like:

/dev/something /data ext3 defaults

3. Umount it:

umount /data

If there are process running on the filesystem you may get a device busy message. If so, you have to stop the applications that are using ig.

4. Mount it again:

mount /data

and try to write on it again.

I followed (I hope) your instructions and here it is what I got. Unfortunately, I'm still unable to cp. I hope I did something wrong!

[root@host11-230-149-62 downloads]# df /home/admin7714990/downloads/
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 149128000 28188636 113241824 20% /

[root@host11-230-149-62 downloads]# grep / /etc/fstab
/dev/sda1 / ext3 defaults 1 1
devpts /dev/pts devpts gid=5,mode=620 0 0
tmpfs /dev/shm tmpfs defaults 0 0
proc /proc proc defaults 0 0
sysfs /sys sysfs defaults 0 0
/dev/sda2 swap swap defaults 0 0

[root@host11-230-149-62 downloads]# umount /
[root@host11-230-149-62 downloads]# mount /
mount: /dev/sda1 already mounted or / busy
mount: according to mtab, /dev/sda1 is already mounted on /

Thenn, when I tried to cp I get the usual error:

[root@host11-230-149-62 downloads]# cp linx-2.1.0.tar linx-2.1.0.1.tar
cp: cannot create regular file `linx-2.1.0.1.tar': Read-only file system

Unfortunately you are trying to write to the root filesystem (/) that can not be unmounted, I'm afraid you have to reboot your server. It's a bit strange to have / in read only, a lot of other process should be failing, have you notice more problems?, try to write something in /tmp or /var in example.

By the way, it's a good practise to create different partitions and not to use only one for /.

Regards,

Alfredo

I know this thread is old (1.5+ years) but I wanted to add a correction to this, as I found it on the first google result list searching for "error copying, read only filesystem". You can remount your filesystem without unmounting and mounting.