# Cannot remount /usr read-only [solved]

## at

I have /usr on a separate partition and would like to remount it read-only.

However, it fails:

```
# mount -v -o remount,ro /usr

mount: /usr is busy
```

There is nothing in the logs.

When I look at the processes using /usr in fuser, I see:

```

supervising syslog-ng

/usr/sbin/syslog-ng

/usr/sbin/sshd
```

and other daemons that are not writing anything in that filesystem and could be just as well run from a read-only filesystem.

Is there anywhere I should look?

Thank you!Last edited by at on Tue May 03, 2011 2:17 am; edited 1 time in total

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## Hu

Do you have any unlinked files on that filesystem?  If a file has been unlinked, but not reclaimed, then the filesystem cannot be remounted read-only.  Unlinked files in /usr are somewhat common if you upgrade a package and do not restart every process that held open a file from that package.

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## at

Thank you for your advice - I will try restarting all the services.

But is there a way to identify those files or processes holding those files?

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## at

Yes, that did it. Thank you!

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## Hu

Yes.  Use lsof to look for deleted files.

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