IBM E16RMLL-I Implementation Guide - Page 538
Diskbuffsize, Tcpbuffsize
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If you set the RESOURCEUTILIZATION option to enable multiple client/server sessions and are backing up direct to tape, you must also update the server option MAXNUMP for client node maximum mount points allowed. The following factors can affect the throughput of multiple sessions: The server's ability to handle multiple client sessions. Is there sufficient memory, multiple storage volumes, and CPU cycles to increase backup throughput? The client's ability to drive multiple sessions (sufficient CPU, memory, and so on). The configuration of the client storage subsystem. File systems that are striped across multiple disks, using either software striping or RAID-5, can better handle an increase in random read requests than a single drive file system. A file system on a single drive may not see performance improvement if it attempts to handle many random concurrent read requests. Sufficient bandwidth in the network to support the increased traffic. These are some potentially undesirable aspects of running multiple sessions: The client could produce multiple accounting records. The server may not start enough concurrent sessions. To avoid this, the server MAXSESSIONS parameter must be reviewed and possibly changed. A query node command may not summarize client activity. 15.4.2 Communication This section covers client options to influence the performance and behavior of communication protocols between client and server. DISKBUFFSIZE The DISKBUFFSIZE option specifies the maximum disk I/O buffer size (in kilobytes) that the client may use when reading files. Optimal backup, archive, or HSM migration client performance may be achieved if the value for this option is equal to or smaller than the amount of file read ahead provided by the client file system. A larger buffer will require more memory and may not improve performance. This option replaces the formerly available LARGECOMMBUFFERS option. We recommend keeping the default value unless otherwise advised by IBM support. TCPBUFFSIZE The TCPBUFFSIZE option specifies the size of the internal TCP communication buffer that is used to transfer data between the client node and the server. A 508 IBM Tivoli Storage Manager Implementation Guide
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