Forum Discussion

MetalGirl's avatar
MetalGirl
Level 3
12 years ago

NetBackup 6.5.4 - Changing Buffer size - New Tape Drive

I am receiving the error “bptm(pid 3692) the tape device at index -1 has a maximum block size of 32768 bytes, a buffer size of 65536 cannot be used.” I have tried researching this error, but I am not finding anything that applies to my setup. The version we are using is Veritas NetBackup 6.5.4, and this is a new Overland tape drive. We have two other Overland tape drives that are working just fine. Did I miss a configuration step when we swapped out our third tape drive? From my research it sounds like I need to increase the buffer size, but I cannot find out HOW to increase the buffer size. Does anyone here know..? I appreciate any help.

 

Thank you!!

7.1.x and Earlier
Backing Up
Backup and Recovery
Configuring
Error messages
NetBackup
Windows Server (2003-2008)
  • mph999's avatar
    mph999
    12 years ago

    This is usually caused by a limitation of the HBA, nothing to do with NBU of the drive itself.

    The tape drive tuning is set in two files

     

    <install path>\veritas\netbackup\db\config\NUMBER_DATA_BUFFERS

    Eg, 16 32 64 128 256 and so on (128 or 256 seems to good performance, but it is try and see)

    <install path>\veritas\netbackup\db\config\SIZE_DATA_BUFFERS

    eg (32768 65536  131072  262144 )

    For modern drives, 262144 is a common value that gives good performance).

    Martin

  • Mark_Solutions's avatar
    Mark_Solutions
    Level 6
    12 years ago

    Not sure if you have more than one media server but every media server needs to have the buffer files to be able to use them - i doubt that is the issue if they are scsi attached

    Perhaps during the swapout the SCSI card has reset itself so do look at that first as this is where the limit is set.

    So take in the registry under HKLM\System\CurrentControlSet\Services\DeviceDriver\Parameters\Device\ looking for your SCSI device as the "devicename"

    Look for the value of MaximumSGList - this needs to be enough to allow the 64kb or more setting - here is an adaptec artice explaining it:

    http://ask.adaptec.com/app/answers/detail/a_id/17088/~/how-to-change-the-block-size-%2F-transfer-size-under-windows%3F

    A driver upgrade may also help, if it is an adaptec card DO NOT use Windows drivers - they are very, very slow!

    Hope this helps

  • MetalGirl's avatar
    MetalGirl
    Level 3
    12 years ago

    Alrighty, I have updated the firmware on one of the tape drives (but not the one that wasn’t working). The one that wasn’t working was already at version 5.10. These are fairly old tape drives (Overland ArcVaults 24)  and it looks like this firmware update (from 2008) is the last one that was released. If I’m wrong please let me know! So, now all three of them are at version 5.10.

     

    The file type for the NUMBER_DATA_BUFFERS and SIZE_DATA_BUFFERS is just “file” not .txt.

     

    It looks like we are using the Microsoft drivers (for the Medium Changers) which I will be looking in to replacing, but all three tape drives are using the same version driver. The only difference I can really see is with the drivers for the Tape Drives. The two working ones are Hewlett Packard LTO Ultrium-3 version 1.0.5.2, and the one that isn’t working has a newer version Hewlett Packard LTO Ultrium-3 1.0.7.0.

     

    Another good tid bit about our set up is that the one that is not working is plugged into a media server and the two working ones are plugged into the master server.

     

    I’m going to try updating the drivers for the medium changer, but I don’t think that is the cause of this particular problem. However, they may help with our speed issue.

     

    Mark_Solutions, I will also be looking into the SCSCI settings you mentioned, but if anybody else has more suggestions I would very much appreciate it! Even though this is a very annoying problem I am learning a lot!

  • StefanosM's avatar
    StefanosM
    Level 6
    12 years ago

    Try to move the non working drive to the master server for test.

    If will work, then the scsi card on the media server is the problem (card itself, firmware,drivers) .

  • MetalGirl's avatar
    MetalGirl
    Level 3
    12 years ago

     I apologize for the delay, but it is a never ending stream of things that need to be done. Luckily I was able to get the tape drive to start cooperating by doing this:

    1. Deleted the device and the robot from NBU on the master server
    2. Shut down all three tape drives
    3. Shut down both the master sever and the media server
    4. Turned on all three tape drives
    5. After all three tape drives were completely up I turned on the servers
    6. Then once everything was up I re-added the device and robot into NBU

    And it has been working just fine ever since (the past week and a half). Thank you again for all the help! I learned a lot from all the troubleshooting!

  • Marianne's avatar
    Marianne
    Level 6
    12 years ago

    Are you saying that the buffer size error disappeared by just shutting down and restarting everything?

    No buffer size file was modified on the media server and no registry setting changed?

    Weird.......... 

  • Ankit_Maheshwar's avatar
    Ankit_Maheshwar
    Level 5
    12 years ago

     

     

     

    Marianne!! Not sure but i think after making changing the value of size_data_buffer and number_data_buffer we need to restart the services.

    MetaGreil created the number_data_buffer file but didn't restarted services.

     

    So after restarting the services its working fine..

     

     

     

    Ankit 

  • mph999's avatar
    mph999
    Level 6
    12 years ago

    No, no retstart required.

    These values are read by bptm, so the only thing that needs to happenn, is bptm has to start a new process.  It will do this when a new backup starts.

  • mph999's avatar
    mph999
    Level 6
    12 years ago

    Agree with Marianne, strtange solution, didn't expect that.

    Sometimes, a restart / reconfig  / reboot fixes things, even though there is no real reason it should.

    With drive/ library issues, it is quite often worth doing this at the beginning of the problem, it might fix things, and even if not, you have eliminated the restart/ reconfig as a possible cause.

    I've only even seen HBA issues cause this fault in the past, so that was a anew one to me ..