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Cisco MDS 9000 Family Fabric Manager Configuration Guide
OL-17256-03, Cisco MDS NX-OS Release 4.x
Chapter 48 Configuring FCIP
Using the FCIP Wizard
Figure 48-24 FCIP Tunnels (Advanced) Tab
Step 3 Check or uncheck the Write Accelerator check box.
Step 4 Choose the appropriate compression ratio from the IP Compression drop-down list.
Step 5 Click the Apply Changes icon to save these changes.
FCIP Tape Acceleration
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 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 FCIP 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 Figure 48-25 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 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.
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