These instructions explain what to do with a newly inserted mSATA SSD disk or an USB drive which oddly is not partitioned yet.

When the new mSATA SSD has been hardware installed it has no partitions. It has to be done because making a new file system require a partition.

Login with SSH to the router with Putty or from the command line:

$ ssh root@192.168.1.1

A new disk is assigned with a letter and it has to be identified. Do this by communicating directly with the Linux-kernel in /proc directory with grep:

root@turris:~# grep -v ram /proc/partitions
major minor  #blocks  name

  31        0       1024 mtdblock0
  31        1       7168 mtdblock1
   8        0  234431064 sda
 179        0    7634944 mmcblk0
 179        1    7633920 mmcblk0p1
 179       24       4096 mmcblk0rpmb
 179       16       4096 mmcblk0boot1
 179        8       4096 mmcblk0boot0

Here we see a new disk called sda, and as there is no sda1 it has not been partitioned yet. The disk can also be seen in the /dev directory with the command ls -l /dev/sd?:

root@turris:~# ls -l /dev/sd?
brw-r--r--    1 root     root        8,   0 Nov 27 20:50 /dev/sda

A disk can be partitioned in 4 primary partitions or several extended partitions. Typically 1 partition with one file system is recommended for most use. To partition the disk use the fdisk program and make 1 partition with all the space available. Run the command fdisk /dev/sda. Press p to print the current partitions. Press n to make a new partition and p for a primary partition. You will be asked about First sector and Last sector with minimum and maximum as default so just press ENTER to those questions. Press w to write the new partition layout. Here is what you will see:

root@turris:~# fdisk /dev/sda

Welcome to fdisk (util-linux 2.29.2).                                                                                                                                                                           
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x7a924c4c.

Command (m for help): p
Disk /dev/sda: 223.6 GiB, 240057409536 bytes, 468862128 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x7a924c4c

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 
First sector (2048-468862127, default 2048): 
Last sector, +sectors or +size{K,M,G,T,P} (2048-468862127, default 468862127): 

Created a new partition 1 of type 'Linux' and of size 223.6 GiB.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

Now the disk has one unformatted partition which can be seen with ls and grep:

root@turris:~# ls -l /dev/sd*
brw-r--r--    1 root     root        8,   0 Nov 27 20:50 /dev/sda
brw-r--r--    1 root     root        8,   1 Nov 27 20:50 /dev/sda1
root@turris:~# grep sda /proc/partitions 
   8        0  234431064 sda
   8        1  234430040 sda1

Now you should make a file system on the new partition.

Alternative to fdisk you can use the more user-friendly full screen menu driven cfdisk: