Performance tuning for LAN-free environments

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 IBM Spectrum Protect 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 IBM Spectrum Protect 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; IBM Spectrum Protect Data Protection products generally benefit from SAN efficiencies.
When you configure IBM Spectrum Protect 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 IBM Spectrum Protect client and IBM Spectrum Protect 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 IBM Spectrum Protect server-side data deduplication. You cannot bypass the server if server-side data deduplication is used to reduce redundant objects processing.