LAN-free backup can improve performance because the backup
traffic can be routed over the SAN instead of the LAN. LAN-free data
movement can make LAN bandwidth available for other uses and decrease
the load on the Tivoli® Storage
Manager server,
allowing it to support a greater number of concurrent client connections.
Backing up data to tape or disk over the SAN, or restoring data
from tape or disk over the SAN, has the following advantages over
equivalent operations that are performed only over the LAN:
- Metadata is sent to the server over the LAN; sending metadata
over the LAN has negligible impact on LAN performance. Client data
bypasses the potentially busy and slower LAN and is sent over the
faster SAN. Backing up or restoring data over a SAN is generally faster
than the same operation over a LAN.
- Sending client data over the SAN frees the Tivoli Storage
Manager server from
the task of handling data, which leads to more efficient use of server
resources because the data goes directly to storage.
- Using a SAN is more efficient than a LAN when you are protecting
large files, or databases; Tivoli Data
Protection products generally benefit from SAN efficiencies.
When you configure
Tivoli Storage
Manager in a SAN
environment, consider the following points:
- Ensure that you provide a sufficient number of data paths to tape
drives.
- Backing up many small files directly to a real tape device can
be inefficient. For file systems that have many small files, consider
sending the files over the LAN to a disk storage pool, and migrate
the files to tape later.
- Optimize the transaction size for writing files to tape or disk;
for information, see Optimizing the transaction size.
- To improve backup and restore performance, include lanfreecommmethod
shardemem in the client options file if the storage agent
and client are on the same system. Setting this option allows the Tivoli Storage
Manager client and Tivoli Storage
Manager storage
agent to communicate by using RAM, instead of using TCP/IP.
- Set the tcpnodelay option to YES,
in the server or client options. This setting allows packets that
are smaller than the maximum transmission unit (MTU) to be sent immediately.
Do not use LAN-free backup and restore if you are using Tivoli Storage
Manager server-side
data deduplication. You cannot bypass the server if server-side data
deduplication is used to reduce redundant objects processing.