Is there a way to specify the number of sessions when using LiteSpeed with TSM?
There is no Litespeed parameter to control how many sessions a TSM client uses.
On the client side this is controlled by the “resourceutilization” parameter. Your “maxsessions” parameter is a TSM server side setting.
Additional Information:
Here's some information which may help. More details can be found via the IBM support site.
RESOURCEUTILIZATION
Resourceutilization is a client option used to regulate the level of resources (i.e. number of concurrent sessions) the TSM client and server can use during processing. Multiple sessions are created automatically through a single invocation of a TSM backup/restore or archive/retrieve command.
Even though the multi-session function is transparent to the end user and is started automatically, there are some parameters which enable the user to customize the function.
There is a way to influence the multi-session function with the option RESOURCEUTILIZATION. This option increases or decreases the ability of the Tivoli Storage Manager client to create multiple sessions. For Backup or Archive the value of RESOURCEUTILIZATION does not directly specify the number of sessions created by the client. However, this setting specifies the level of resources the Tivoli StorageManager server and client can use during backup or archive processing. The higher the value, the more sessions the client can start if it deems necessary. The range for the parameter is from 1 to 10. When the option is not set, which is the default, then only two sessions are created to the server.
Default resourceutilization level allows up to two sessions with the server, one for querying the server and one for sending file data. Resourceutilization=5 permits up to four sessions (two for queries and two for sending data), while resourceutilization=10 permits up to eight sessions (four for queries and four for sending data) with the server. The relationship between Resourseutilization and the maximum number of sessions created is part of an internalized algorithm and, as such, is subject to change. This table lists the relationships between Resourceutilization values and the maximum sessions created. Producer sessions scan the client system for eligible files. The remaining sessions are consumer sessions and are used for data transfer. The threshold value affects how quickly new sessions are created.
Table 2. Resource Utilization Settings
|
RU Value |
Max # of Sessions |
Unique # of Producer Sessions |
Threshold (secs) |
|
1 |
1 |
0 |
45 |
|
2 |
2 |
1 |
45 |
|
3 |
3 |
1 |
45 |
|
4 |
3 |
1 |
30 |
|
5 |
4 |
2 |
30 |
|
6 |
4 |
2 |
20 |
|
7 |
5 |
2 |
20 |
|
8 |
6 |
2 |
20 |
|
9 |
7 |
3 |
20 |
|
10 |
8 |
4 |
10 |
|
default (0) |
2 |
1 |
30 |
Backup throughput improvements that can be achieved by increasing the Resourceutilization level will vary from client node to client node. Factors that affect throughputs of multiple sessions include the configuration of the client storage subsystem (i.e. layout of file systems on physical disks), the client's ability to drive multiple sessions (sufficient CPU, memory), the server's ability to handle multiple client sessions (CPU, memory, number of storage pool volumes), and sufficient bandwidth in the network to handle the increased traffic.
The MAXSESSIONS parameter controls the maximum number of simultaneous client sessions with the Tivoli Storage Manager server. The total number of parallel sessions for a client is counted for the maximum number of sessions allowed with the server. For this reason, you need to consider whether to increase the value of the MAXSESSIONS parameter in the server option file.
When using the Resourceutilization option to enable multiple client/server sessions for backup direct to tape, the client node maximum mount points allowed parameter, MAXNUMMP, must also be updated at the server (using the Update Node command).
If the TSM client has a filesystem spread across multiple disks (RAID 0 or RAID 5), or multiple large filesystems, we recommend setting the TSM client option Resourceutilization to a value of 5 or 10. This will enable multiple sessions with the server during backup or archive, and can result in substantial throughput improvements in some cases. It is not likely to improve incremental backup of a single large filesystem with a small percentage of changed data. If backup is direct to tape, then the client node maximum mount points allowed parameter, MAXNUMMP, must also be updated at the server using the update node command.
When a restore is requested, the default is to use a maximum of two sessions, based on how many tapes the requested data is stored on, how many tape drives are available, and the maximum number of mount points allowed for the node.
The default value for the RESOURceutilization parameter is one (1) and the maximum value is ten (10).
For example, if the data to be restored are on five different tape volumes, and the maximum number of mount points is five for the node requesting the restore, and RESOURceutilization is set to three, then three sessions will be used for the restore. If the RESOURceutilization setting is increased to five, then five sessions will be used for the restore. There is a one-to-one (1:1) relationship to the number of restore sessions allowed and the RESOURceutilization setting.
