16–Using Cavium Teaming Services
Application Considerations
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Because there are four client servers, the backup server can simultaneously
stream four backup jobs (one per client) to a multidrive autoloader. Because of the
single link between the switch and the backup server, however, a 4-stream
backup can easily saturate the adapter and link. If the adapter on the backup
server operates at 1Gbps (125MBps), and each client is able to stream data at
20MBps during tape backup, the throughput between the backup server and
switch will be 80MBps (20MBps × 4), which is equivalent to 64 percent of the
network bandwidth. Although this is well within the network bandwidth range,
64 percent constitutes a high percentage, especially if other applications share
the same link.
Additional information for teaming and network backup is covered in these
sections:
Load Balancing and Failover
As the quantity of backup streams increases, the overall throughput increases.
Each data stream, however, may not be able to maintain the same performance
as a single backup stream of 25MBps. In other words, even though a backup
server can stream data from a single client at 25MBps, it is not expected that four
simultaneously-running backup jobs will stream at 100MBps (25MBps × 4
streams). Although overall throughput increases as the quantity of backup
streams increases, each backup stream can be impacted by tape software or
network stack limitations.
For a tape backup server to reliably use adapter performance and network
bandwidth when backing up clients, a network infrastructure must implement
teaming such as load balancing and fault tolerance. Data centers will incorporate
redundant switches, link aggregation, and trunking as part of their fault tolerant
solution. Although teaming device drivers will manipulate the way data flows
through teamed interfaces and failover paths, this is transparent to tape backup
applications and does not interrupt any tape backup process when backing up
remote systems over the network.
shows a network
topology that demonstrates tape backup in a Cavium teamed environment and
how smart load balancing can
load balance
tape backup data across teamed
adapters.
There are four paths that the client-server can use to send data to the backup
server, but only one of these paths will be designated during data transfer. One
possible path that Client-Server Red can use to send data to the backup server is:
Example Path: Client-Server Red sends data through Adapter A, Switch 1,
Backup Server Adapter A.
