Unix questions - visited by the read-only demon

Author

visited by the read-only demon

Jim Showalter

2006-11-16, 7:20 pm

Greetings!

For about five days last week, every few times it tried to download
mail, my email client failed, reporting that the FAT32 file-system on
drive /e, was read-only. And sure enough, entering "touch /e/t" gave:
"touch: cannot touch `/e/t': Read-only file-system".

The first time this happened, I examined everything I thought relevant.
The contents of /etc/fstab, the output of mount and all the directory/
file permissions were unchanged!

Note: /e is mounted at boot by user 'jim', the mount point and every
file on the file-system belong to jim. This had worked flawlessly
for five months.

There are more details available in the thread "Thunderbird making
FAT32 readonly file-system" in the "netscape.public.mozilla.mail-news"
newsgroup where I was trying to get help with this problem last week.

The problem has now disappeared just as mysteriously as it began,
leaving me really curious, especially about the following.

During the time this was occurring I could replicate the problem when
the file-system was Ok, simply by issuing the following commands as a
normal user:

jim@atlas:~> touch /e/t
jim@atlas:~> chmod -w /e/t
jim@atlas:~> rm /e/t
rm: cannot remove `/e/t': Read-only file system
jim@atlas:~>

But since the problem has disappeared, the same sequence produces:

rm: remove write-protected regular empty file `/e/t'? y
jim@atlas:~>

as you would expect.

My question: How could making one file read-only cause the entire
file-system to become read-only?

droid
--
I know what I believe. I will continue to articulate what I believe and
what I believe - I believe what I believe is right. --George W. Bush
* Now that's articulate! *

Bill Marcum

2006-11-17, 1:25 am

On Thu, 16 Nov 2006 23:09:14 GMT, Jim Showalter
<jshowalter@spam.gmail.com> wrote:
> Greetings!
>
> For about five days last week, every few times it tried to download
> mail, my email client failed, reporting that the FAT32 file-system on
> drive /e, was read-only. And sure enough, entering "touch /e/t" gave:
> "touch: cannot touch `/e/t': Read-only file-system".
>
When a file system suddenly becomes read-only, it is usually a sign that the
drive is failing. Check the system logs and try "smartctl -a /dev/hd?"

>
> My question: How could making one file read-only cause the entire
> file-system to become read-only?
>
It can happen if there is an error reading or writing the sector where the
file's directory information is stored.

--
If you didn't have to work so hard, you'd have more time to be depressed.

Jim Showalter

2006-11-18, 1:29 am

Bill Marcum wrote:

> When a file system suddenly becomes read-only, it is usually a sign that the
> drive is failing. Check the system logs and try "smartctl -a /dev/hd?"

Good to know. This is the only thing that seems to make sense of what
I've been seeing.

But I found no smoking gun in /var/logs. What particular logs should I
pay attention to?

>
> It can happen if there is an error reading or writing the sector where the
> file's directory information is stored.

Partition Magic reported errors, so I moved all the data to another
drive. Everything is working fine! Thank you Bill!

Cheers!
droid
--
I know what I believe. I will continue to articulate what I believe and
what I believe - I believe what I believe is right. --George W. Bush
* Now that's articulate! *