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Re: [Linux-cluster] fencing issue - with attach logs&conf


It's been my understanding that the kernel panic technique you are describing essentially is undesirable for the fact that the kernel is in an unknown state. Basically anything can happen. The OS doesn't have to do a sync for an hba do flush etc. Since RedHat isn't in the business of building there own hardware like HP(DEC), Sun, IBM, they take the next best route to ensure that nothing from that problematic machine can affect the storage and the only way to guarantee that is to remove power from the whole machine.

VMS and Tru64 use the panic method but the other nodes will issue a reservation on the scsi bus against that node to protect the storage. They can do that because they know exactly how there hardware and implementation of reservations work.


On Thu, Mar 4, 2010 at 5:32 AM, שלום קלמר <sklemer gmail com> wrote:
Thanks to all !!!!
Shalom klemer hp com

On Thu, Mar 4, 2010 at 12:00 AM, Lon Hohberger <lhh redhat com> wrote:
On Wed, 2010-03-03 at 13:10 +0200, שלום קלמר wrote:
> Hi.
> I got 2 power supplies. But if someone by mistake pull the power
> cables , is that mean
> That the services will not failover ??

The problem is:

no power = no ping + no DRAC access
no network = no ping, no DRAC access

If there's no power, then it is safe to fail over.

If there is no network (and power is OK), then it is not safe to fail
over.  Failover in this case is very likely to produce data corruption!

Because we can not tell which case happened, we do not fail over.

-- Lon

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