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BirtyB's avatar
BirtyB
Level 4
10 years ago

Heavy disk usage on Media server when idle

Hi all,

Our NBU 7.6.3 deployment is still in pre-production and yesterday, for the first time we ran a couple of test VM backups.  The backup completed successfully however almost immediately after the backup completed, and still 24 hours later, I see heavy disk reads on the LUN that hosts the Dedupe store.  If I look at the Disk tab within Windows Resource Monitor I see the following (see attachement).

This storage is connected via iSCSI if that makes a difference...

Is this expected?

Thanks in advance,

Graham

7.6
Backup and Recovery
NetBackup
Windows Server (2003-2008)
  • BirtyB's avatar
    BirtyB
    10 years ago

    Hi all, sorry for the lack of updates.  As above the problem went away when we recreated the MSDP volume on a thick provisioned LUN.  Thanks for your help.

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  • BirtyB's avatar
    BirtyB
    Level 4
    10 years ago

    Another attachment showing NIC bandwidth history on the storage unit.

  • AAlmroth's avatar
    AAlmroth
    Level 6
    10 years ago

    I'd say it is the normal maintenance jobs in your MSDP disk pool.

    Have a look in the file Q:\dedupe\log\spoold\storaged.log

    It should give an idea of what it is currently doing.

    The spoold process should also be quite busy.

     

    /A

     

     

  • BirtyB's avatar
    BirtyB
    Level 4
    10 years ago

    Thanks for your help.  The log is ful of these:

    October 30 01:11:10 ERR [000000000A01AF40]: 25048: _storeGetCRCCheckCandidateFromJournal: can't fsync file Q:\Dedupe\databases\datacheck\crc_check_write: (invalid file descriptor)

  • AAlmroth's avatar
    AAlmroth
    Level 6
    10 years ago

    I have never really seen that error, but the fsync would indicate it is unable to flush data to disk. Perhaps you should open a support case with Symantec.

    In the meantime: Do you use antivirus scanner? Perhaps try disabling scan of Q drive, or relevant processes such as spoold.exe

     

    /A

     

  • Nicolai's avatar
    Nicolai
    Moderator
    10 years ago

    Likely - MSDP pool does a lot of housekeeping (space reclaim, integrity checking etc) when idle.

    http://www.symantec.com/docs/HOWTO89134

    http://www.symantec.com/docs/TECH124914

  • jim_dalton's avatar
    jim_dalton
    Level 6
    10 years ago

    I know nothing of this facet but if I were to see messages along the lines of "datacheck" and "crc " I'd be thinking: data corruption. Worrying...

    JIm

  • BirtyB's avatar
    BirtyB
    Level 4
    10 years ago

    I've opned a case with Support.  It seems to partly be down to the fact that the MSDP LUN was thin provisioned.  I've since recreated the LUN as think provisioned and am using nbperfchk to make sure the storage is up to the task.   I'll update this thread when I know more.

  • BirtyB's avatar
    BirtyB
    Level 4
    10 years ago

    Hi all, sorry for the lack of updates.  As above the problem went away when we recreated the MSDP volume on a thick provisioned LUN.  Thanks for your help.