From owner-freebsd-scsi  Tue Apr 21 10:50:10 1998
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From: dan@math.berkeley.edu (Dan Strick)
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Date: Tue, 21 Apr 1998 10:49:51 -0700 (PDT)
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To: hans@artcom.de, pantzer@ludd.luth.se
Subject: Re: SCSI-Disk hot-swappability?
Cc: freebsd-scsi@FreeBSD.ORG
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> Why not just type this in your configfile for the kernel?
> 
> disk    sd0 at scbus0 target 0 
> disk    sd1 at scbus0 target 1
	...
> > The sd driver seems to be prepared for this, but the necessary changes to
> > scsiconf.c do not seem to be there.  We'd also need a set of utilities to
> > make the kernel reprobe a given SCSI device.
> 
> The manpage for scsi tells me that it can do that.

There may be a problem.  I tried it once and it didn't work.
This was a while back, so perhaps it is old news.

I actually prefer static drive unit definitions over dynamic
definitions (at least for the first few drives) because then file
systems don't move around on you when a drive dies.

Some additional considerations:

1) It would be nice if the SCSI disk driver would react to
   an attention condition on a drive by reloading the disk
   labels.  It would be nice if this produced console/syslog
   messages.

2) I once turned an external drive off for a while a while
   because it was so terribly noisy.  After I turned it back
   on, it was so terribly slow.  Speculation: the synchronous
   transfer parameters were not renegotiated.

3) Since attention conditions might be missed, it would be
   nice if the drive was also "reinitialized" during each
   drive open().

Dan Strick
dan@math.berkeley.edu

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