[Lustre-discuss] lctl deactivate questions

[Craig Prescott]

Brian J. Murrell wrote:
> On Tue, 2008-02-05 at 10:50 -0500, Craig Prescott wrote:
>> However, 'lfs df' on the clients does not show
>> that the OST is deactivated there, unless we *also*
>> run the lctl deactivate there.  Then the OST shows
>> up as 'inactive' on the client, and we get the same
>> message as above in the client's syslog.
> 
> Do you really want the OST deactivated on the clients?  I think your
> goal is to effectively remove the OST from further space allocation
> decisions, yes?  You still want the data on the OST available to clients
> to read or overwrite, correct?  Deactivating on the clients will make
> the OST completely unavailable to the clients, even for read operations.

Thanks for your answer - that was what I wanted to know.
Yes, we only want the OST removed from further space
allocation decisions.

>> So I have a question - if I want to deactivate an OST
>> (preventing new files from being written to it) while
>> I sort out what files to shuffle off of a full OST,
>> where should I run 'lctl deactivate'?
> 
> On the MDT.  Deactivation on the MDT prevents the MDT from further
> allocating objects on it, but does not prevent clients from reading or
> writing to existing objects.

Got it.  Thanks again.

Cheers,
Craig