I am trying to use an Integral 256Gb USB stick on a Vigor 2925 router for ad-hoc file backups. I am using firmware version 3.9.4 (I'm aware that there's a 3.9.5, I tried to install it this morning and it seemed to go through OK but the old version is still showing - now everyone's streaming stuff and I can't try it again! - but 3.9.5 release notes don't mention anything about USB).

I am aware of the requirement to format the stick as FAT32:

"Only support FAT16 and FAT32 format, FAT32 is recommended.... Only support to mount single partition, maximum capacity is 500GB. If there are more then one partition, only one of them will be mounted."

And I've also seen this: https://faq.draytek.com.au/2019/12/23/what-is-the-size-limit-of-the-usb-drive-on-a-draytek-router/

I used "guiformat.exe" to reformat the drive to FAT32 using 32K allocation units (came as exFAT). There's only one volume on it. The stick appears to be using an "MBR" partition table.

When I connect the USB stick I see this in "USB Device Status":

Connection Status: No Disk Connected
Disk Capacity: 237999 MB
Free Capacity: 0 MB

So it seems like the disk is recognised to some extent because it shows the total size of it. I am wondering if the allocation unit size is the problem and if the FAT drivers only support certain allocation units.

Just wondering if anyone has any insight into this before I wipe off what's already on the stick and start blindly trying different settings.

I've got a USB stick stuck in my 2925, somewhat smaller in capacity than yours though.

Connection Status: Disk Connected
Write Protect Status: No
Disk Capacity: 29510 MB
Free Capacity: 25783 MB Refresh

Had it in for a couple of years over various firmware versions, currently on the latest

Current Firmware Version: 3.9.5

You could try deleting all the partitions in diskmanager and creating a new one.

Thanks for the feedback mbames. I've tried a smaller stick (32Gb) and that works OK. I think I'll have to wipe the larger stick and keep trying progressively larger partitions until I find the cutoff point.

I finally succeeded in getting it to work. I am not quite sure what the key to it was, but what I did was:

• Removed all the volumes and partitions from the stick

• Created a partition in DiskPart that was slightly smaller than the capacity:

Code:

create partition primary size=230000

• An unformatted volume is created with a drive letter (E in my case)

• Formatted the volume using fat32format.exe, just using the defaults:

Code:

C:>fat32format.exe e: Warning ALL data on drive 'e' will be lost irretrievably, are you sure (y/n) :y Failed to allow extended DASD on deviceSize : 241GB 471040000 sectors 512 Bytes Per Sector, Cluster size 32768 bytes Volume ID is fe9:1b31 32 Reserved Sectors, 57486 Sectors per FAT, 2 fats 7358203 Total clusters 7358202 Free Clusters Formatting drive e:... Clearing out 115068 sectors for Reserved sectors, fats and root cluster... Wrote 58914816 bytes in 2.42 seconds, 23.20 Megabytes/sec Initialising reserved sectors and FATs... Done

I am not sure if it was the partition size or the mix of different software that clinched it.