Re: Anyone used Solaris Secure Shell, Sun's productized ssh for Solaris9?

From: Joerg Schilling (js@cs.tu-berlin.de)
Date: 02/08/02

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    From: js@cs.tu-berlin.de (Joerg Schilling)
    Date: 8 Feb 2002 09:49:38 GMT
    
    

    In article <a3von0$1555$2@agate.berkeley.edu>,
    Akop Pogosian <akopps+usenet@ocf.berkeley.edu> wrote:

    >>>>Except that rdist/ufsrestore/ufsdump etc will still want to use
    >>>>/usr/sbin/in.rshd and not ssh (they dont execute /usr/bin/rsh but use
    >>>>the rsh "protocol" directly)
    >>>
    >>>which is why you either use newer versions of rdist, or invoke
    >>>ssh more directly for ufsdump/ufsrestore, and use dd for the pipe, etc.
    >
    >> This makes you backup slow and wears out the tapes because of frequent
    >> tape repositioning -> unreliable backups.
    >
    >By the way, this problem exists even when doing backups over rsh when
    >doing incremental backups of file systems where only a small portion
    >of files has changed and data can't be sent fast enough to keep the
    >tape streaming. I wish ufsdump had a mechanism for buffering data on a
    >disk on the tape server and then writing it in large chunks to reduce
    >the tape drive wearing because of using ssh or slow incremental
    >backups.

    With star you can do this:

            star bs=256k fs=128m f=ntape@somehost:/dev/rmt/0cbn ....

    It will give you a tape buffer size of 256kB and a 128MB buffer local to
    the star side of the connection.

    128 MB of FIFO is no problem for a machine with 256+ MB of ram and
    gives you additional 10+ seconds for a DLT drive.

    As there is a major limitation for speed by the network connection,
    a buffer on the remote tape host will not help much more.

    >From my experiences, the tape usually streams for many minutes if you
    use star to create your backup.

    -- 
    EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
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