• iSCSI can directly address remote (FC or iSCSI) block storage devices across a WAN
• Bandwidth and especially latency are key concerns
Remote backup may become a key application for iSCSI. iSCSI can be used to enable “remote tape vaulting” solutions in which backups are located at a distance from the primary data centre. iSCSI allows customers to move backups off-site for disaster protection. Remote backup solutions are complex solutions that require careful planning and performance tuning. Tape drives are streaming media devices—data is read and written sequentially at a constant speed. If the storage network cannot supply data as fast as the tape drive writes data, or if the data stream is interrupted, the tape drive must stop, rewind to the last written byte, and restart. High latency may be tolerable if it is consistent, but varying latency can be a problem. If bandwidth is too low or latency varies too high, backup performance will be severely degraded due to the constant tape drive reset operations. Proper IP network design is crucial for remote tape backup operations.