backup running slow for 1 client

[Venu_S1]

We have 850 Client machines , all are transfering datas in good speed but one client machine is taking too long to transfer a datas ..... that is ...backup should complete within 2 hours ..but after 12 hours and more ...the data transfer is still happening.... 

Could you please suggest what we need to check to resolve this problem

[Topher-lab]

I would suggest the following:

Review the path the data is traversing from he client to the end storage unit to identify any possible bottlenecks, that is to say, any points where there may be congestion of traffic.

If the bottlneck is more likely on the client, review the BPBKAR log at "verbose 5" and "general 2" to get an idea of speed per file backed up (this is not intuitive in the logs, but possible).  There is also a test that can be run on the client to test reading speeds of the client's data.  Pages 101-102 of the NetBackup 7.0/7.1 Backup Planning and Performance Tuning Guide describes how to use 'bpbkar -nocont' to do this (this still applies to 7.5).

Next, look at differences between this client's performance and the client most similiar with better performance and then review the more subtle differences to help identify if it may be affected by the software on the client (AntiVirus, for example) or by configuration differences (TCP Offloads/TCP Fusion, for example).

[RonCaplinger]

Topher's suggestions are great, they are some of the first things to look at.  Assuming you have other backups that are going through the same media server to the same backup location (disk/tape), then it is likely not a NetBackup issue.

A few other things to check on the client:

• Are the client's TCP settings correct?  If the NIC is set to 10Mbps, but is capable of 1Gbps, or if the NIC is set to half-duplex, you will see much slower speeds.
• Is the client busy with heavy I/O applications or databases?  This will limit the speed at which the disk drive may transfer data. I have seen some older clients that meet the application owner's expectations, but running a backup of that client is just enough to cause swapping of data to/from disk, again slowing down the backup which will typically occur when users are not using the system so it goes unnoticed.
• Make sure the clients Windows Event logs or Unix syslogs are clear and don't indicate performance issues.
• Check the NIC for high TCP retransmits.  If so, you might want to try replacing the ethernet cable(s) from the client to the switch.  Weak cables can cause a high number of retransmits.
• If all else fails, open a support case with Symantec and they can instruct you on how to run a "sequencer" application between the client and media server to determine if there is a switch or other point in the path that is causing the slowness.