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DragonFly users List (threaded) for 2005-12
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Re: Waiting 15 seconds for SCSI devices to settle *groan*

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 1 Dec 2005 14:02:36 -0800 (PST)

:Hi Emiel.
:> antiquated SCSI peripherals that actually do need 15 seconds ;) ) If yes, 
:> I'll just shut up about this.
:Well an old SGI Octane2 each with several (2 or 3) SGI "Vaults" (external SCSI drives)
:need definitely more than 15 seconds. "Antiquated"? Maybe. But I know
:of several (about 50) of such configurations in a productive environment.
:On the other hand I think you can lower the time to 5 seconds with "modern" 
:equipment ...

    The big problem that we had in the 'early' days (circa 1995) was with
    SCSI tape drives.  I can well believe the SGI Vaults had a problem.  
    The problem isn't really device initialization time, its that old SCSI
    devices often wouldn't even 'appear' on the SCSI bus until after a
    lengthy initialization period.  Modern devices appear on the SCSI bus
    pretty much immediately and simply tell the host to hold on a minute
    if queried before they are finished initializing themselves (spinning
    up spindles, self-check, closing the CDROM tray, etc). 

					Matthew Dillon 

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