Cisco ASA5500-HW - Hardware Accessory Kit Network Device Hardware Installation Manual page 14

Chapter 1 ASA Chassis Overview
External USB Support
For information about IPS functionality within ASA, see Cisco Intrusion Prevention System
documentation at the following URL:
http://www.cisco.com/en/US/docs/security/ips/7.1/roadmap/19889_01.html
External USB Support
The Cisco ASA 5500-X series chassis have internal and external USB drives that use FAT32 file system.
Internal USB Drives
Embedded USB (eUSB) devices are used as the internal flash (disk0).
External USB Drives
The ASA 5500-X series is the first ASA hardware platform to support external USB flash drives for data
storage. Previous ASA platforms allowed an external compact flash that supported Online Insertion and
Removal (OIR), where disk1: became the unique identifier. The ASA 5500-X series follows this model,
using disk1: as the external USB flash drive identifier. When the ASA is powered on, an inserted USB
flash drive is mounted to disk1: and available for you to use. Additionally, the file system commands that
are available to disk0: are also available to disk1, including copy, format, delete, mkdir, pwd, cd, and
so on. When you remove the USB flash drive, the system unmounts disk1:, and disk1: becomes an invalid
file system label that you can no longer access.
Because the disk allowance is restricted to 2 disks (labeled as disk0 and disk1), and disk0 is occupied by
the internal eUSB on the ASA, disk1 is the disk label for the external USB drive. In this way, the system
mounts only one partition. For example, if you insert a USB drive with more than one partition, only the
first partition is mounted.
OIR Support
While the ASA back panel has two USB slots, only one is supported for OIR, with priority given to the
USB drive that was inserted first. For example, based upon the time sequence, the first inserted USB
flash drive is mounted to disk1, regardless of the slot in which you insert it. When you insert a second
USB device, an error message displays on the console to notify you that an extra, unsupported USB flash
drive exists. Removing either one of the USB devices does not change the priority that you just
established. To change the priority you must safely remove the USB device and begin again to establish
the desired priority.
FAT File System
The ASA 5500-X series supports only FAT32 formatted file systems for the eUSB and external USB
drives. It is important that the first partition of the inserted USB drive is in the FAT format. If it is not,
the system mounting process fails, and you receive an error message. You can enter the format disk1:
command to format the partition to FAT 32 and mount the partition to disk1 again: however, data might
be lost.
Cisco ASA 5500-X Series Hardware Installation Guide
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