Very, very, VERY weird event

[Graham Watkins]

On 27/09/14 15:03, Rashkae wrote:
> On 14-09-26 10:54 PM, Karl Auer wrote:
>> Here's a good one.
>>
>> I logged into my home server to start a backup. Ran "mount" to see if
>> the backup disk had mounted itself. It had - but two other USB HDDs
>> normally mounted on boot were apparently not mounted! Argh! Home
>> directories and a bunch of other stuff are on those drives, so this was
>> a big problem.
>>
>> Note: The "mount" command showed no drives mounted except the internal
>> HDD.
>>
>> I thought "darn, things will have been written to the mount points on
>> the internal HDD", and sure enough, lots of files were visible under the
>> mount points. So to see what sort of job I had ahead of me, I ran "du
>> -s" on one of the mount points - and it said there were 57GB of data
>> under it.
>>
>> Note: The internal HDD has one partition, of 10GB. "df -k" reported only
>> 3GB used.
>>
>> I placed a new file in the mount point directory, and rebooted. The
>> external HDDs mounted as normal - and the new file was visible on the
>> mounted drive! Everything seems back to normal as far as I can tell.
>>
>> So it looks to me as if the drives were mounted all along, but the
>> "mount" utility was not reporting them.
>>
>> Google is not much help because all the terms are so common (mount, USB
>> etc).
>>
>> Is this something anyone else has seen? Are there any reliable ways to
>> see what's mounted apart from the "mount" command? I stupidly didn't
>> check /proc/mounts...
>>
>> Regards, K.
>
> I found this paragraph in the mount man page:
>
> When the proc filesystem is mounted (say at /proc), the files
> /etc/mtab and /proc/mounts have very similar contents. The for‐
> mer has somewhat more information, such as the mount options
> used, but is not necessarily up-to-date (cf. the -n option
> below). It is possible to replace /etc/mtab by a symbolic link
> to /proc/mounts, and especially when you have very large numbers
> of mounts things will be much faster with that symlink, but some
> information is lost that way, and in particular using the "user"
> option will fail.
>
>
> If I understand the information correctly, the mtab file is not assured
> to be correct, and if you need a more 'canonical' listing of current
> mount points, /proc/mtab is what you need to check.
>
> However, I think the question of *why* your mtab wasn't up to date
> remains. The only reason I can think of is that for some reason, your
> root filesystem was read only at the time the usb discs were mounted.
>
>
>
>
It's very much a "newbie" solution and possibly not what you are looking 
for, but I have added disk mounter to my desktop panel. It shows what is 
and isn't mounted and permits disks to be mounted and unmounted with a 
left mouse click.

Cheers,

Graham