Backup throughput dropping off dramatically

Posted on 2004-11-02
Last Modified: 2013-11-15
I have a server attached to an emc SAN  that is backed up to a Quantum, ATL library. This is attached w/2GB fibre.  I used to get 1500MB to 1700MB p/min throughput on my backup but lately it has dropped off to 65mb per minute and then that drops off to 45-35 mb after awhile. So far I have moved data off of luns that where filling up and i have defraged the drives on the server. Is there anything else I can do?  How can I tell if the HBA is going bad? Backup software used in Brightstor Enterprise 10.5
Question by:blee5
    LVL 22

    Expert Comment

    There is a utility called RawRead which measures the throughput of harddrives. This is to help find out if the problem is at the drive end.

    Another thing to do is enable logging on the switch during a backup. A lot of times this is an easy way to see on which side the problem is. For example  the port going to the server has little to know errors but the port going to the library has lots. At that point the problem has been cut in half.

    I have not used EMC stuff but it probably has it's own logging that can be enabled.

    To test to see if the bottleneck is at the tape drive end run the command "simulate -ca". This lets you create an imaginary tape device. So data is read from the source and is processed in the normal way up to the point of being written to tape where it is just dumped since there is not a physical drive. In this case it might be a pain to test. Any BEB Distributed servers will have to have BrightStor shut down and only the Primary running. Simulate will replace the current configuration so after removing the simulated device it will be necessary to run Device Confguration again to setup the library. That's why it is a bit of a pain.

    That brings up a good point, if there are Distributed servers check to see if they have the same problem.

    Does the BEB server have just one HBA?

    Author Comment

    Actually the Brightstor Server that is having the issue is a distributed server with one HBA that connects to the SAN and another HBA that connects to to the Library.
    LVL 22

    Accepted Solution

    That helps. Since the BEB Primary server does not have this problem you know it is somewhere between the switch and this system. Question is if it is the system or the SAN.

    To test the system Performance Monitor or Task Manager can be used to check system resources. Look for a steady decline in available resources.

    At the SAN end good old swapping might be the easiest way of testing. Since this server has two HBAs, how about swapping the cables. If LUN Masking is not setup then all there is to worry about is the zoning. If the zoning was setup via the port then it should not be a problem at all. If zoning is setup for the HBAs world wide name then it will have to be modified. Another test would be swapping ports at the switch. Between the two tests you will have tested the HBA, cable, GBIC, and port.


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