[geeks] WTB: FH 5.25" SCSI-1 enclosure

David Passmore geeks at sunhelp.org
Sun Nov 25 02:08:38 CST 2001


On Sun, Nov 25, 2001 at 01:29:58AM -0500, Joshua D Boyd wrote:

> A tekky on campus (employee in computer center, not student) said that 
> technically, external SCSI is meant to be hot swappable, and usually if there 
> are problems it is either from incorrect SCSI cards, or OSs that support it 
> proper.  I thought that sounded cool, but I've never heard it from anywhere 
> else.

The real problem with disconnecting SCSI devices on a chain is electrical
termination. When we were running lots of dual-initiator A3500s, we
developed an 'official' procedure to disconnect a host which involved
unplugging the cable from the A3500 and plugging a terminator in its
place as quickly as possible. If you lose termination on a SCSI chain you're
toast; you'll have SCSI packets spilling off the end of your cable and all
sorts of nasty things will happen.

Note that this is not a problem with fibre channel. :)

David



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