Correct Answer: B
Explanation/Reference:
Explanation:
Tapes are storage devices that store and retrieve user data sequentially. Cisco MDS NX-OS provides both tape write and read acceleration.
Applications that access tape drives normally have only one SCSI WRITE or READ operation outstanding to it. This single command process limits the benefit of the tape acceleration feature when using an FCIP or FC tunnel over a long-distance WAN link. It impacts backup, restore, and restore
performance because each SCSI WRITE or READ operation does not complete until the host receives a good status response from the tape drive. The
SCSI tape acceleration feature helps solve this problem. It improves tape backup, archive, and restore operations by allowing faster data streaming
between the host and tape drive over the WAN link.
In an example of tape acceleration for write operations, the backup server in the following figure issues write operations to a drive in the tape library. Acting as a proxy for the remote tape drives, the local Cisco MDS switch proxies a transfer ready to signal the host to start sending data. After receiving all the data, the local Cisco MDS switch proxies the successful completion of the SCSI WRITE operation. This response allows the host to start the next SCSI WRITE operation. This proxy method results in more data being sent over the FCIP or Fibre Channel tunnel in the same time period compared to the time taken to send data without proxying. The proxy method improves the performance on WAN links.
Reference: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/mds9000/sw/5_0/configuration/guides/ioa/ioa/scsi_wa_ta.html
