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Uninstalling and reinstalling external hard drive causes network connection loss

Posted on 2008-06-12
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Hi all,

This question is a follow-up to one I previously posted, in which my SBS 2003 R2 machine would lose internet connectivity seemingly at random.  I've since determined that it's not (completely) at random, but happens (sometimes) when I remove and install a device.

Here's the situation.  I've got an on-board Broadcom NetXtreme dual-port GbE adapter, which is the external-facing adapter for the server.  Also on this machine is a Rosewill RC-216 eSATA RAID adapter, which is connected to an external 2-bay hot-swap enclosure.  I've got several sets of hot-swap disks, configured in JBOD, which I use as backup media.  Each morning, after the nightly backup is complete, I swap out the pair that's in the enclosure with another pair.  The arrays are named BACKUP A, BACKUP B, etc.

The backup drives don't show up as removable devices on the system (instead, the array shows up as "BACKUP A SCSI Disk Device," which is strange because they're not SCSI).  In order to safely remove them, I created a simple batch file:

@ECHO OFF
DEVCON REMOVE *BACKUP*
ECHO Press any key when the drives have been switched ...
PAUSE
DEVCON RESCAN

which uninstalls (exactly as would happen if you uninstalled from Device Manager) any device whose description contains "BACKUP", and then scans for new devices after a keystroke.  This seems to work fine.  Often when this script runs, however, the machine loses internet connectivity.  No errors pop up, and the Broadcom still shows as installed and connected, but I can't ping external IPs.  If I go into the Broadcom control suite and run a Cable Analysis test (which seems to force a restart of the NIC), connectivity is restored.

I've noticed that both the Broadcom adapter and the Rosewill adapter share IRQ 16, but I didn't think this was an issue in modern incarnations of Windows.

Any suggestions?
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Question by:jhodgesiv
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by:plug1
ID: 21770243
What happens if you simply remove the disk and re add the new ones without running your re-scan. Do you think the rescan is discovering your network adaptors incorrectly?
After all if they are hot swap drives then the rescan isnt needed is it?
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by:jhodgesiv
ID: 21770500
It's a hot-swap enclosure, but the drives aren't showing up as AHCI hot-swap drives.  I'm wary of removing them without letting the OS know about it, because I want to make sure that they aren't being written to when I remove them (to avoid data corruption).

The network adapter is never removed, and it doesn't show as discovered in the rescan.  If I just do the rescan without removing the drives, the problem doesn't happen.  I'm thinking the issue has to do with the OS allocating resources to the "new" drive that are used by the Broadcom NIC, but I'm not sure where to look to try to dig deeper into this.
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by:plug1
ID: 21770553
I'd take the plunge and remove and re-add without the rescan, it should be tottaly external to the OS and handled by the backplane itself.
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Author Comment

by:jhodgesiv
ID: 21779010
After looking around a bit more on this issue, it appears the command I should have been using was "devcon disable" rather than "devcon remove"; I found a nice GUI utility that does just this at http://mysite.verizon.net/kaakoon/hotswap/index_enu.htm.  I'll see after a few days whether the problem recurs (though I'm still baffled as to why what I did would create those symptoms).
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by:plug1
ID: 21779024
Have you tried it without the script yet, I think its totally unneccesary
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jhodgesiv earned 0 total points
ID: 21823895
plug1:

You're right that, if I were guranteed there was no activity on the drive at the time of removal, just removing the drives would be fine.  However, SATA hotswap support doesn't protect against data loss from hotswapping if there's read/write activity; rather, it protects against data loss due to electrical issues from the sudden disconnection.  For example, if the OS isn't accessing the disk at the time of removal, the drive and its contents will be fine; if, however, the OS is writing a segment, or editing the filesystem tables, serious corruption could result from the tasks being unable to complete (it's the same as the system losing power in the middle of an operation).  Since this is a backup solution, I need to be as sure as possible that the data is safe -- it won't do to have a backup that can't be read in an emergency.

That said, there is an additional problem with simply removing the drives without doing *something* in the OS.  If the drives are removed without OS notification, the OS doesn't remove the device or reassign the drive letter to the new drive.  This is a problem because a) my backup system is designed to write to a single drive letter, and b) if any programs (such as virus scanners or indexers) try to access the drive, my logs will fill up with errors.

The Hotswap! utility I linked to above has done the trick, though.  Since I started using it, the problem has not recurred.  I did get a couple of atapi device errors the first day, but they haven't shown up again.

Thanks for your help.
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