[CentOS] forcing device to USB HDD

Hi, I bought an USB external hdd (500GB) to make my
backups using dump... but, sometimes my sever
recognize the hdd device /dev/sdb or /dev/sdc... my
question is: How can I assign a fixed device for
example /dev/sdc to my hdd? remember I use some
scripts to do my backup and I am getting errors
because the device changes from sdb to sdc and 

thanks in advance
Israel



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