How to Format USB Flash Drive for Cisco Catalyst 9300 and Other Cisco Switches

Properly formatting a USB flash drive is critical for Cisco Catalyst switches and other Cisco hardware. It ensures your devices recognize the USB during IOS upgrades, config backups, software recovery, and diagnostics. This guide explains what format your USB needs to be for Cisco switches, how to format on Windows, macOS, and Linux, and how to verify recognition using Cisco CLI.

What Format Does a USB Need to Be for a Cisco Switch?

Cisco Catalyst switches (9300, 9200, 3850, 3650) require USB flash drives to be formatted in FAT32 for maximum compatibility during IOS upgrades and configuration transfers. FAT16 is also supported (mainly for older devices). exFAT is not reliably recognized for IOS upgrades.

For Cisco USB 3.0 SSD (e.g., SSD-240G) used on Catalyst 9300, the required file system is EXT4 (EXT3, EXT2 also supported), while NTFS, exFAT, VFAT are not supported.

Cisco USB File System Compatibility Table

What Size USB Drive for Cisco 9300?

Cisco Catalyst 9300 switches support USB drives up to 32 GB reliably for IOS upgrades. Larger drives may work but can face compatibility issues depending on the file system and IOS version. For Cisco USB 3.0 SSD, the supported size is 240 GB (SSD-240G).

How to Format a USB Flash Drive for Cisco Switches on Windows

1. Insert the USB drive into your Windows PC.
2. Open File Explorer > This PC, right-click your USB drive, select Format.
3. Choose:
   • File System: FAT32
   • Allocation unit size: Default or 4096 bytes for many small files
   • Volume label: (e.g., CISCO_USB)
   • Check Quick Format
4. Click Start and confirm.

How to Format a USB Flash Drive for Cisco Switches on macOS

1. Insert the USB drive and open Disk Utility.
2. Select the USB drive (entire drive).
3. Click Erase:
   • Format: "MS-DOS (FAT)" (FAT32)
   • Scheme: "Master Boot Record (MBR)"
   • Volume label as needed
4. Click Erase to complete.

How to Format a USB Flash Drive on Linux for Cisco Switches

Using GParted (GUI):

1. Insert the USB drive.
2. Open GParted, select your USB device.
3. Unmount, delete existing partitions, apply.
4. Create a new partition with fat32, apply.

Using Command Line:

sudo fdisk -l              # Identify device (e.g., /dev/sdb1)
sudo umount /dev/sdb1      # Unmount
sudo mkfs.fat -F 32 /dev/sdb1   # Format as FAT32

How to Format Cisco USB 3.0 SSD on Catalyst 9300 (EXT4)

To format a Cisco USB 3.0 SSD for the Catalyst 9300:

Device# format usbflash1: ext4

For stack members:

Device# format usbflash1-2: ext4

How to Verify USB Recognition on Cisco Switches

After formatting and inserting your USB:

• Check if detected:

  Switch# show file systems

• List contents:

  Switch# dir usbflash0:

• Check media:

  Switch# show media

• Copy IOS image:

  Switch# copy usbflash0:cat9k_iosxe.17.09.04.SPA.bin flash:

Frequently Asked Questions (FAQs)

What format does a USB need to be for a Cisco switch?

FAT32 is the recommended and most compatible format for USB flash drives on Cisco Catalyst switches for IOS upgrades and config transfers.

How to format a USB flash drive on Linux?

Use GParted or the mkfs.fat -F 32 command to format your USB drive to FAT32, ensuring compatibility with Cisco switches.

What size USB drive for Cisco 9300?

A 16 GB to 32 GB USB flash drive is ideal for Catalyst 9300 switches for IOS upgrades, minimizing recognition issues.

Does Cisco support FAT32?

Yes, FAT32 is fully supported on Cisco Catalyst 9300 and other IOS/IOS XE switches for image transfers and configuration backups.

Troubleshooting USB Flash Drive Not Recognized

• Reformat to FAT32 (or EXT4 for Cisco USB 3.0 SSD).
• Use a different USB drive if compatibility issues persist.
• Reinsert the USB drive to retry detection.
• Use show usb device to check support.
• For Cisco USB 3.0 SSD:
  • Check security status:

    Device# show hw-module usbflash1 security status

  • Unlock if locked:

    Device# hw-module switch 1 usbflash1 security unlock password 

  • Unmount before removal:

    Device# hw-module switch 1 usbflash1 unmount

• Review console logs for specific errors if unrecognized.

Best Practices

• Always back up important data before formatting.
• Use FAT32 for general Cisco switch operations.
• Use EXT4 for Cisco USB 3.0 SSD on Catalyst 9300.
• Unmount Cisco USB 3.0 SSD before removal.
• Use a 16–32 GB drive for upgrades for higher reliability.
• Label USB drives for tracking during large-scale deployments.

By following these steps, network engineers can efficiently format USB drives for Cisco switches and ensure consistent, reliable IOS upgrades and maintenance workflows.