Partition/formatting/labeling issues with new external HD

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routerguy

Occasional Visitor
Hi everyone,

I recently bought a 8TB to replace my 4TB backup/media drive which is attached to my RT-AC56U router running Asuswrt-Merlin.

Disk was probably formatted NTFS out of the box, so (as recommended by many) I SSHed to my router and formatted it to ext4 (using mke2fs -t ext4).

Everything seems to be good, except that the drive now shows up mounted as sda2 and not as sda1 like my old drive used to (not tragic, but somewhat inconvenient because it means I'd have to relink/rescan links and databases referring to content on the drive, including Kodi).

So I started looking into ways to change the disk level (which seems easist). Here's where I ran into problems...

Code:
# fdisk -l

Disk /dev/mtdblock0: 0 MB, 524288 bytes
255 heads, 63 sectors/track, 0 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/mtdblock0 doesn't contain a valid partition table

Disk /dev/mtdblock1: 1 MB, 1572864 bytes
255 heads, 63 sectors/track, 0 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/mtdblock1 doesn't contain a valid partition table

Disk /dev/mtdblock2: 65 MB, 65011712 bytes
255 heads, 63 sectors/track, 7 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/mtdblock2 doesn't contain a valid partition table

Disk /dev/mtdblock3: 63 MB, 63316992 bytes
255 heads, 63 sectors/track, 7 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/mtdblock3 doesn't contain a valid partition table

Disk /dev/mtdblock4: 65 MB, 65798144 bytes
255 heads, 63 sectors/track, 7 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/mtdblock4 doesn't contain a valid partition table

Disk /dev/mtdblock5: 1 MB, 1310720 bytes
255 heads, 63 sectors/track, 0 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/mtdblock5 doesn't contain a valid partition table
fdisk: device has more than 2^32 sectors, can't use all of them
Found valid GPT with protective MBR; using GPT

Disk /dev/sda: 4294967295 sectors, 2047G
Logical sector size: 512
Disk identifier (GUID): 9240905d-56d0-4428-971f-1cc8f15f94c0
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 15628053133

Number  Start (sector)    End (sector)  Size       Code  Name
   1              34          262177        128M   0700  Microsoft reserved partition
   2          264192     15628052479       7451G   0700  Basic data partition

So I missed that Microsoft reserved partition - meh.

Seems like I'm having some problems here which I need to fix. Not sure, however, if I fully understand what's going on. Does anyone have more insight?

I guess I can get this ironed out by hooking up the machine to my windows computer and formating it from scratch with Partition Manager (get rid of the MS partition, use GPT instead of MBR for the partition table and relabel it), but I'm not exactly looking forward to moving over 4TB of data to the disk yet again, so if there's an easier path, I'd really be happy.

Thanks a bunch!
 

bbunge

Very Senior Member
Go backto the 4 TB as that is the max size for your router.
Or split the 8 TB into two partitions. And with a drive that big you should have a swap on a thumb drive.
Better yet invest in a NAS.
 
Last edited:

Yota

Regular Contributor
For disks larger than 2TB, you must use GPT format. If you create GPT under Windows, Microsoft reserved partitions will always be created by default.

My suggestion is to use the command-line tool diskpart under Windows to create GPT disks without Microsoft reserved partition, so you may have to reformat.
 

routerguy

Occasional Visitor
Thanks, Yota. As it turns out, the disk was already using GPT format, and fdisk output was just the consequence of fdisk not understanding that format.

I then used MiniTool Partition wizard to at least remove the Microsoft partition, but for some reason, Asuswrt didn't want to mount it anymore after that. So instead of spending hours figuring out why, I've decided to reformat the disk anyway. Oh well.
 

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