How to hot-swap SCSI drives

How to hot-swap SCSI drives

Post by Dan Smit » Thu, 29 Mar 2001 12:08:27



I have two SCSI adapters: Adaptec 2940, Tekram DC390U2W(sym53c8xx)..

If I do a hot-swap of a drive, how do I get the system/card to
recognize the change?

Thanks!

--Dan

 
 
 

How to hot-swap SCSI drives

Post by Kelledi » Thu, 29 Mar 2001 13:26:16


You can try the scsiadd utility at http://llg.cubic.org/misc/, within
certain limitations.  Heed well the caveats!

If you're trying to manage a JBOD, I don't know of anything better.  If
you're trying to manage a RAID array, I'd suggest you get a hardware RAID
controller.

Kelledin, the Dreaming Minstrel
http://kelledin.tripod.com/scovsms.jpg

 
 
 

How to hot-swap SCSI drives

Post by Dan Smit » Thu, 29 Mar 2001 13:59:48


Uhh, ok... What's is JBOD?

What caveats are there to consider?  Both adapters say they are
hot-swap compliant.

Thanks!

--Dan

 
 
 

How to hot-swap SCSI drives

Post by Frank Schaefe » Fri, 30 Mar 2001 00:45:53


"JBOD" is an acronym for "just a bunch of disks."  (Ya, they thought
pretty * that name ;) )  That's what I suspect you're trying to
manage.

The main caveats:

scsiadd doesn't always work if you have multiple SCSI buses (i.e.
multiple adapters or a dual channel adapter).  scsiadd can change the
device mappings (i.e. /dev/sda might not refer to the same SCSI hard
drive after you've run scsiadd), confusing apps which acess these device
files.  scsiadd should not be run if it might re-map a device file
that's currently open (i.e. /dev/sda0 is mounted on /, but running
scsiadd forces /dev/sda0 to point to a partition on some other SCSI hard
drive.  Such a radical change while the drive is mounted tends to make
the entire system crash)

Basically, you need to make sure that scsiadd won't cause any open
device files to map to different hardware than they currently map to.
This requires you to know the basic methodology the kernel uses to map
SCSI device files to hardware.

Kelledin, the Dreaming Minstrel
http://www.veryComputer.com/

 
 
 

How to hot-swap SCSI drives

Post by See signature for email addres » Fri, 30 Mar 2001 03:45:41



> I have two SCSI adapters: Adaptec 2940, Tekram DC390U2W(sym53c8xx)..
> If I do a hot-swap of a drive, how do I get the system/card to
> recognize the change?
> Thanks!
> --Dan

To add a device to a bus after you have connected it, try the following:

echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
        * with  "0 1 2 3" replaced by your "Host Channel Id Lun".

To remove a device, you do the following:

Usage: echo "scsi remove-single-device 0 1 2 3" >/proc/scsi/scsi
     * with  "0 1 2 3" replaced by your "Host Channel Id Lun".

These commands are considered BETA.

====================================================================
Khalid Aziz                             Linux Development Laboratory
(970)898-9214                                        Hewlett-Packard

 
 
 

1. Hot-Swap IDE drives

 I have been looking at purchasing an ORB drive for backup, but noticed
that
 some say the drive has poor reliability (www.computers.com). With the
low
 price/MByte of IDE drives I was starting to consider hot-swapable drive
kits
 (www.hival.com, www.promise.com).

 I am looking for a capability that is truely hot-swapable, like a zip
drive
 but with low-cost IDE drives. What I have seen so far requires a full
reboot
 of the system. Does anyone know the details on how this might work?

 I dont think it is as simple as unmount, then swap,
 then remount. From reading other posts, I assume that the bus needs to
be
 rescanned after swapping, with what commands? I have also seen
references
 that the hot swap frame needs must be designed to prevent electrical
damage
 to the hard disk being swapped.

 Any information on this subject is appreciated, even wrt to SCSI bus.

----------------------------------------
  David G. Bishop

----------------------------------------

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