Data Protector A6.10 and LTO 6

I have a Quantum Scaler i40 library with an Ultrium LTO 6 drive. It is connected to a Windows Server 2003 R2 with a SAS connection and if I try and backup a local drive in the server the max speed I can acheive is 8MB/s which it slower than a Windows copy/paste.

I have mad sure that the driver, library and SAS HBA are all using the latest drivers and firmware and that the drive and library are healthy. However I am unable to get a faster write time.

 

Can anyone suggest anything.

  • First, according to the Device support matrix

     

    http://support.openview.hp.com/selfsolve/document/KM718727/5049eb547ecf6173e77df9e0/Device_Support_Matrix_6.1x.pdf

     

    this is an unsupported configuration, DP 6.10 only supports up to LTO-4.  I am not even sure if LTO-6 is supported on the latest version of DP

     

    Having said that, I would look at concurrency as being a posible cause for this.  Concurrency is the number of data streams that can be written to a media at the same time

     

    Modern tape drives are capable of writing much faster than most data gets sent to them, so, as a result, there is sometimes a point where the tape drive stops, and waits for the Tape buffer to fill.  When it is sufficiently filled, teh tpe has to re-position to the last file mark with some buffer characters, and starts writing to the tape again until, again, the tape buffer empties

     

    To avoid this, you increase the concurrency to 10 -> 15, or even more.  This is done in the Propertis of teh tape drive in the Backup specification -> Destination tab

     

    Of course, you have to have enough data stremas to make use of the concurrency.  A data stream is an Object (mounted File System), so, if you are only backing up 3 objects, you will never meet the concurrency value, and your backup will continue to be slow

     

    I am going to try and attempt to attach a powerpoint presentation that illustrates this

  • Thanks Bob,

     

    I'm suprised to hear of possible library/drive compatibility issues as I was assured by the supplier that is was fully compatible:

     

    http://h10032.www1.hp.com/ctg/Manual/c01631143.pdf

     

    Thanks for the advice on conccurancy, I will try that this morning and will also go through the ppt you attached.

     

    Thanks again,

     

    Matt

  • Hi Matt,

     

    LTO6 is a hell of a data sink and needs powerful hardware to be driven to expected throughput (it got better rate matching than LTO5, though). Servers from the age of Win2003R2 may actually be on the brink of not being adequate, depending on the block size in use. For LTO6, I would recommend 512KiB or more, with 256KiB as the absolute minimum in case it is unavoidable for compatibility reasons. Everything smaller and a BMA may overload a CPU core before reaching a streaming rate, let alone LTO6 full blast. That's orthogonal to the need for multiplexing (or staging) as communicated by Bob, given it is hard to find sources that can conjur up data that fast, specifically from the age in question.

     

    HTH,

    Andre.