Re: filer to SCSI-attached tape drive performance

From: A Darren Dunham (ddunham@taos.com)
Date: Thu Oct 18 2007 - 13:14:11 EDT

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    On Thu, Oct 18, 2007 at 11:06:00AM -0500, John Foley wrote:
    >
    > - is there a way to tell what the data rate to the tape drive is
    > from the filer, over the SCSI bus ? I'm looking for more of an
    > instantaneous measurement, rather than the overall average of
    > (amount of data moved / time it took).

    Are you looking at sysstat? It has a tape performance column.

    > - anyone else played around with this (ie, attempting to measure the
    > data throughput from filer to SCSI attached tape drive) ? If so,
    > what did you try, and what conclusions did you reach ?

    What is the rate you're getting?

    Is this with 'dump' or some commercial backup package? I might want
    to compare the speed between the backup package, just running a 'dump'
    on the same filesystem (will eliminate the production of catalog
    history data), and running a dump to the 'null' device. If the filer
    is under load, the tape drive may not be your bottleneck.

    -- 
    Darren Dunham                                           ddunham@taos.com
    Senior Technical Consultant         TAOS            http://www.taos.com/
    Got some Dr Pepper?                           San Francisco, CA bay area
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