These are mainly USB thumb drives. I don't know if there's a hard limit on the size of the usb storage device that's supported, but I have used up to 32gig-sized devices & on various ASR1K devices.
Cisco has finally got inline with other network hardware vendors, who have always allowed active FileSystem mounting ( e.g what the folks at Juniper, Arista, etc...... have done )
To mount the usb device, just stick it in the USB slot. ( yes, it's really that easy ! )
You don't have to worry about any un-mount options, but if you are in fear of FileSystem corruption, you can enable shell access, and use the linux unmount command
( enabling shell access YMMV use at YOUR OWN RISK , CISCO strongly suggest you don't enable shell access!)
You can use the following cisco commands to validate it's mount;
- dir usb0:
- show usb0:
- show usb-device
or by executions of a combination of show_cmds or linux commands ( df , mount, ls ,etc.....)
( IOS-XE show commands )
NOTE1: logging is NOT ALWAYS output under 15.1.x code to show that the device was removed, which really sucks btw
( sample log entry via syslog )
NOTE2: a stand-alone cdrom will typically draw too much current and will NOT mount. This will generate a log message btw
NOTE3: a stand-alone ext-USB-HDD will typically draw too much current and will NOT mount.
( using linux via a shell )
( 32gig device and our proc entry for usb device )
Mounting a device to the linux kernel, give you greater access for log collections, gather ios-xe files, backups, and host of other hacks.