Events?

Events?

[Leslie Rhorer]

What does the "Events" field reported by -Dt signify, and why does the
number sometimes decrease?  I've seen the number change, but I don't see
anything in any of the system logs corresponding to something that would
seem to relate.

Re: Events?

[Neil Brown]

On Saturday May 30, lrhorer@satx.rr.com wrote:
> 
> What does the "Events" field reported by -Dt signify, and why does the
> number sometimes decrease?  I've seen the number change, but I don't see
> anything in any of the system logs corresponding to something that would
> seem to relate.

Changes just as device failure and adding or removing a device.
Also transitions from 'active' to 'clean' and back.
Sometimes the dirty->transition causes the event counter to retreat if
md is use the new 'clean' state is indistinguishable from the old
'clean' state.  This allows us not to always be waking up spare drives
just to tell them about clean->active->clean transitions.

NeilBrown

RE: Events?

[Leslie Rhorer]

> -----Original Message-----
> From: Neil Brown [mailto:neilb@suse.de]
> Sent: Saturday, May 30, 2009 4:47 PM
> To: lrhorer@satx.rr.com
> Cc: linux-raid@vger.kernel.org
> Subject: Re: Events?
> 
> On Saturday May 30, lrhorer@satx.rr.com wrote:
> >
> > What does the "Events" field reported by -Dt signify, and why does the
> > number sometimes decrease?  I've seen the number change, but I don't see
> > anything in any of the system logs corresponding to something that would
> > seem to relate.
> 
> Changes just as device failure and adding or removing a device.
> Also transitions from 'active' to 'clean' and back.

OK, but shouldn't these transitions at least be logged somewhere?

> Sometimes the dirty->transition causes the event counter to retreat if
> md is use the new 'clean' state is indistinguishable from the old
> 'clean' state.  This allows us not to always be waking up spare drives
> just to tell them about clean->active->clean transitions.

That makes sense, but I think the admin should be able to inspect the
details of the transactions.

Re: Events?

[SandeepKsinha]

On Sun, May 31, 2009 at 7:07 AM, Leslie Rhorer <lrhorer@satx.rr.com> wrote:
>> -----Original Message-----
>> From: Neil Brown [mailto:neilb@suse.de]
>> Sent: Saturday, May 30, 2009 4:47 PM
>> To: lrhorer@satx.rr.com
>> Cc: linux-raid@vger.kernel.org
>> Subject: Re: Events?
>>
>> On Saturday May 30, lrhorer@satx.rr.com wrote:
>> >
>> > What does the "Events" field reported by -Dt signify, and why does the
>> > number sometimes decrease?  I've seen the number change, but I don't see
>> > anything in any of the system logs corresponding to something that would
>> > seem to relate.
>>
>> Changes just as device failure and adding or removing a device.
>> Also transitions from 'active' to 'clean' and back.
>
> OK, but shouldn't these transitions at least be logged somewhere?
>
>> Sometimes the dirty->transition causes the event counter to retreat if
>> md is use the new 'clean' state is indistinguishable from the old
>> 'clean' state.  This allows us not to always be waking up spare drives
>> just to tell them about clean->active->clean transitions.
>
> That makes sense, but I think the admin should be able to inspect the
> details of the transactions.
>

Yes, this really can be very useful for any inspection, we should
surely log any state changes.


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-- 
Regards,
Sandeep.





 	
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