Permission issues with mounted new hard drive on Ubuntu machine

Question

I recently purchased a new hard drive, for the sole purpose of storing a database. I am running Ubuntu 10.0.4.

Since I had not done this sort of thing before, I decided to use the GUI (Disk Utility) to format and mount the disk (to avoid any snarfus caused by typos etc at the command line).

I correctly identified the new drive and proceeded as follows:

1. Elected to format the drive
2. Selected type: 'Ext4'
3. Selected the 'Take ownership of filesystem' checkbox
4. Unchecked the 'encrypt underlying device' checkbox
5. Provided a name for the new volume (mydata)

Once the device had been formatted, I then mounted the device as follows:

sudo mount /dev/sdb /mydata

I created the directory /mydata/pgdbdata

and changed ownership as follows

sudo chown -R postgres:postgres /mydata/pgdbdata

I check:

username@localhost:~$ ls -l /mydata/
total 20
drwx------ 2 root     root     16384 2012-06-19 23:05 lost+found
drwxr-xr-x 2 postgres postgres  4096 2012-06-20 19:04 pgdbdata

However when I change to postgres user:

username@localhost:~$ sudo su - postgres
postgres@localhost:~$ ls -l /mydata/
ls: cannot open directory /mydata/: Permission denied

Because of this permissions issue, I can start the postgresql service and I can't create the postgresql db cluster. I am stuck.

What am I doing wrong?

Solution

You have only changed permission of pgdbdata but not of mydata you should be able to do a ls -l /mydata/pgdbdata but if your postgresql user wants to see the content of mydata it has to have read access to that too.

Comments

[pl1nk]

From your question I suppose that /media/market_data/ is owned by user and group root. pgdbdata folder has been only chowned to user and group postgres. But you are checking a wrong folder?

[Homunculus Reticulli]

@pl1nk: Sorry. That was a typo. I have corrected the text in my question.

[pl1nk]

You should change the permissions of /mydata/

[Homunculus Reticulli]

Thanks. I don't know why or how I missed that ... Nothing like a second pair of eyes ... :)

[André Stannek]

You're welcome. Sometimes you're just blind. Happens to me all the time ;-)