SUMMARY: Removing and reattaching a SCSI drive to a live system

Christopher L. Barnard cbar44 at
Fri Nov 10 15:10:13 EST 2006

I asked:

> I sometimes use external SCSI drives to move files to isolated servers.
> To do this I plug the SCSI cable of the external drive into an *unused*
> SCSI port of a running system.  I run devfsadm so that the system recognizes
> the new drive, I copy over the files, then unplug the drive.  The running
> server does not complain.  About 99% of the time it works fine:  the system
> reports that the removed drive is "unavailable" but it is still trivial
> to reuse that port.  Occasionally, however, the <drive not available> remains
> when a disk is re-attached, even if I do a new devfsadm.  I know that a
> reboot will clear the list of drives.  But when this happens I usually do
> not want (or cannot) do an immediate reboot.  Does anyone know of a way
> to clear "unavailable" drives without rebooting the system?
> Another way to put it:  Here is the output of a "format" from several
> systems.
>        0. c1t0d0 <SUN146G cyl 14087 alt 2 hd 24 sec 848>
>           /pci at 1c,600000/scsi at 2/sd at 0,0
>        1. c1t1d0 <SUN146G cyl 14087 alt 2 hd 24 sec 848>
>           /pci at 1c,600000/scsi at 2/sd at 1,0
>        2. c2t3d0 <drive not available>
>           /pci at 1c,600000/scsi at 2,1/sd at 3,0
> c1 is the internal controller and c2 is the external SCSI port.  c2t3 is the
> external SCSI disk I move around.  On some servers, if I plug something into
> c2t3, the new disk info will replace the "drive not available".  On others,
> the "drive not available" remains and the system will not recognize the new
> disk.  So on servers that do not recognize anything new in c2t3, I need to
> remove selection 2 from "format" without rebooting the system.

The answer:

I'll just have to wait for the next reboot.  Aside from the couple
of people who responded along the lines of "oh my God, don't do that"
(its safe. really. You just have to do it in the right order.  ;^), people
recommended the -C flag to devfsadm, adding -v as well so that I could see
what was happening, 'update_drv sd', manually deleting the offending
/dev/dsk and /dev/rdsk entries, and cfgadm.  None worked.

Thanks to

Stan.Pietkiewicz at
Susan.Thielen at
Anthony D'Atri <aad at>
Chris Ruhnke <ruhnke at>
Darren Dunham <ddunham at>
Chris Hoogendyk <hoogendyk at>
"Stevens, Adrian" <A.Stevens at>
"Hafiz, W (Waqar)" <Waqar.Hafiz at>
"Lineberger, Aaron" <alineberger at>

| Christopher L. Barnard         O     When I was a boy I was told that |
| cbarnard at         / \    anybody could become president.  |
| (312) 347-4901               O---O   Now I'm beginning to believe it. |
|                --Clarence Darrow |
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