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On Apr 15, 2004, at 2:05 PM, Manuel Bouyer wrote:

>> You'd also have to teach our HBA drivers to not rudely abort other 
>> HBA's
>> queued requests on the whole bus with a SCSI bus reset.
>
> The others HBA drivers should be able to handle this

I think you missed his point.

Consider the following topology:

      Server A -----+----- Server B
                    |
                    |
            Shared Disk Pool

Server A and Server B are coordinating access to Shared Disk Pool, both 
have outstanding commands with the Shared Disk Pool.

Now, Server A reboots (due to a crash or whatever).  NOTE: Server B is 
still using Shared Disk Pool and has outstanding commands!

Right now, when Server A comes back up, it issues a SCSI Bus Reset, 
which KILLS any commands that Server B has running on the Shared Disk 
Pool.  All of those commands error out, and you see a major drop in 
performance as Server B has to recover.

This is not a good thing.  And there is no good reason for Server A to 
issue that SCSI Bus Reset in the first place.

Basically, we should fix our HBA drivers to be good citizens.

         -- Jason R. Thorpe <thorpej@wasabisystems.com>


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