Cartridge ESD discharge during drive loading in a storage system
Original Publication Date: 2001-Aug-29
Included in the Prior Art Database: 2003-Jun-20
In a storage library system a cartridge can build up a charge of 8 to 12 KV while being unloaded from a storage bin, or when an operator moves a cartridge across a non anti-static room from a shelf to a drive for manual loading. Although the picker and/or the drive can be grounded, the build up charge cannot be bled to ground fast enough without affecting the electronic circuitry of other units in the system. Signal voltage spikes of up to 7 Volts on the ground system have been seen when the a charged cartridge contacts the drive loader tray whether manually or via the picker. These type of spikes although narrow can still affect other units in the system while writing or reading. The read/write circuitry, and channel circuitry can be affected and can cause non recoverable errors, which in turn can bring the system to a halt, and a reboot or IML of the entire system becomes necessary, this then becomes very annoying to users. The solution consist of mounting conductive roller/s directly grounded to the picker, and system frame, a picker could have 2 grippers, in this case 2 rollers are required one for the top and one for the bottom. In case of manual system mount the conductive roller on the drive opening of the loader tray directly grounded to the system frame via a braided wire for a faster bleeding response, see figure 1 and 2. When the cartridge is loaded into the drive, the roller will discharge the charged cartridge initially directly to system ground before it is loaded on the tray loader mechanism of the drive, and continue to dissipate the remaining charge if any during the cartridge insertion motion into the drive loader tray, thus avoiding any system noise due to ESD. The conductive roller design demonstrated less ware than a conductive brush, and no potential of debris contamination from the brushes. Adding a lightly loaded spring to the roller will make the design more effective, because it will ensure continuous cartridge contact during the cartridge insertion motion into the drive, since all optical and tape cartridges have non continuous smooth surfaces. The roller could also be used in a DASD RAID system environment, so that when an operator in a non antistatic room is required to swap drives, the other drives in the system are protected from ESD discharge that can interrupt and/or hang the system.