Seagate 5TB External USB - EXT4 - Mounting Read-Only

abbas_qamar · 06-01-2019, 08:11 AM

Hello there,

I just purchased a Seagate 5TB External USB hard drive. Using gdisk, I made partitions and formatted them as EXT4 file system. The partitions auto-mount, but are read-only.

Earlier, the same partitions would mount with read-write. However, the earlier partitions were created using parted and I was seeing alignment errors while formatting with mkfs.ext4 and also while looking at details in fdisk.

So, I deleted the partitions and created them again using gdisk. No alignment issues now. But partitions are mounting read-only.

mkfs.ext4 /dev/sdb1
mke2fs 1.42.13 (17-May-2015)
/dev/sdb1 alignment is offset by 512 bytes.
This may result in very poor performance, (re)-partitioning suggested.

fdisk output
Device Start End Sectors Size Type
/dev/sdb1 65535 976733639 976668105 465.7G Linux filesystem
/dev/sdb2 976733640 1953532814 976799175 465.8G Linux filesystem
/dev/sdb3 1953532815 2930266454 976733640 465.8G Linux filesystem
/dev/sdb4 2930266455 3907000094 976733640 465.8G Linux filesystem
/dev/sdb5 3907000095 4883799269 976799175 465.8G Linux filesystem
/dev/sdb6 4883799270 5860532909 976733640 465.8G Linux filesystem
/dev/sdb7 5860532910 6837266549 976733640 465.8G Linux filesystem
/dev/sdb8 6837266550 7814000189 976733640 465.8G Linux filesystem
/dev/sdb9 7814000190 8790799364 976799175 465.8G Linux filesystem
/dev/sdb10 8790799365 9767533004 976733640 465.8G Linux filesystem

Partition 1 does not start on physical sector boundary.
Partition 3 does not start on physical sector boundary.

ugjka · 06-01-2019, 08:19 AM

Probably nothing to do with how you format the drive but rather what is the ownership and permissions for the root folder of that drive

Post the output of ls -l /path/to/your/mountpoint/

abbas_qamar · 06-01-2019, 08:44 AM

xxx@xxx-laptop /media $ ls -lh
total 4.0K
drwxrwxrwx+ 12 root root 4.0K Jun 1 18:19 xxx
xxx@xxx-laptop /media $ ls -lh xxx/
total 40K
drwxr-xr-x 3 root root 4.0K Jun 1 11:54 0bfd2076-d34e-4b16-aa6a-8efd3e519402
drwxr-xr-x 3 root root 4.0K Jun 1 11:54 22c3076a-6109-49d2-8a94-4c82fb706f2c
drwxr-xr-x 3 root root 4.0K Jun 1 11:54 56670e2d-317e-46d7-93ec-0234237f8137
drwxr-xr-x 3 root root 4.0K Jun 1 11:54 69f8ac8c-1970-458e-8cab-a85ced3d7908
drwxr-xr-x 3 root root 4.0K Jun 1 11:53 7f9279aa-666d-4446-aa8b-8aefc43f0583
drwxr-xr-x 3 root root 4.0K Jun 1 11:53 924e7d6c-7e4f-4ef5-bab7-f3f89792974f
drwxr-xr-x 3 root root 4.0K Jun 1 11:53 9ad55055-d40e-4f37-8ef5-9d8ddc80cdd5
drwxr-xr-x 3 root root 4.0K Jun 1 12:41 9df7397c-ec18-4f77-9d2f-f833367f255d
drwxr-xr-x 3 root root 4.0K Jun 1 11:53 bf29f217-bcf8-4a71-aac1-fc549f2607f3
drwxr-xr-x 3 root root 4.0K Jun 1 11:53 d10d677f-3e19-4510-b532-4e2a85cc040a
xxx@xxx-laptop /media $

The partitions mount to /media/xxx/
I chmod /media/xxx/ giving 777 permissions thinking it would inherit to the folders underneath. However, the partitions that mount in this path, don't inherit the permission.

ugjka · 06-01-2019, 08:49 AM

It seems all files belong to both root user and root group

I suppose your user is xxx, so you could try changing the ownership:

Code:

chown -R xxx:xxx /media/xxx

You'll need root permission to perform that action

abbas_qamar · 06-01-2019, 09:06 AM

Many thanks for your help and guidance, ugjka!
I can mount the partitions with read/write.

hydrurga · 06-02-2019, 06:57 AM

Great to hear. If you want, you can mark the thread as "Solved" (see "Thread Tools" at the top of the thread).

Shadow_7 · 06-03-2019, 12:11 AM

$ mount

If it's actually read-only it'll show (ro,... ) to the side of where it was mounted. Otherwise it's a permissions issue as previously discovered. I didn't even know that you could change the root of an ext* partition. I always just created a sub-directory and chown'd that. But probably more of an effort to avoid lost+found in the usable path with the temptation to delete it. With a 2nd mount to bind the /mnt/ location with where I actually wanted it, like /home/username/.

# mount --rbind /mnt/p1/subdir /home/username

With systemd, you can boot with the / of your distro NOT specified in /etc/fstab. But it will mount read-only when that is the case. Which was my first thought when I read the thread title.

business_kid · 06-03-2019, 01:50 PM

I have this in my /etc/fstab for sdb1

Code:

/dev/sdb1	 /mnt/hd	  auto	      noauto,relatime,diratime,user,exec,dev,suid,nofail     0   0

A lot of those options are for usb keys, but 'user' 'noauto' and suid (I think) help with user writes as long as it's ext2/3/4. I can mount sdb1 if it's ext or vfat (until recently anyhow) but not ntfs-3g. With a user option in sr0, I can mount that too as a luser. But if I let it mount automatically, root mounts it and my luser is locked out. If I don't have it mount automatically, and it's in fstab, a luser can mount it.

If I wasn't so half-assed, I'd go to uuids and have each disk mounted on it's own location. I'm in Slackware, where you do your own thing. If you have a distro that makes up your mind for you, this could be a lot messier.

Shadow_7 · 06-03-2019, 08:12 PM

My stab has UUID=... / ext4 defaults 1 0 and all that jazz. But I set my UUID to something simple to remember / type.

UUID=20190603-1000-1111-1111-111111111111

Where that's the YYYYMMDD that I created it and the HHMM, although I always put 00 for minutes. I don't normally do more than one install in a day, much less per hour. And mostly UUID because I boot from USB and /dev/??? is an unknown depending on how many other devices, hubs, and whatnots are in play. And the rest is what partition it's on.