Some questions about ctdb availability when some node is crashed

[ronnie sahlberg]

Is it really a persistent database you are using ?

What does   'ctdb getdbmap' show ?



On Sat, Nov 17, 2012 at 8:50 PM, Christopher R. Hertel <crh at samba.org> wrote:
> Az,
>
> The command you are executing is:
>
>   ctdb pstore test.tdb /tmp/test /tmp/test
>
> So are you using the file pathname ("/tmp/test") as the key?  I think that
> makes sense, but it is a little confusing to read.
>
> I find it interesting that the pstore subcommand is not listed in the man
> page for ctdb.  It was added in 2010, I believe.
>
> Chris -)-----
>
> On 11/16/2012 10:02 AM, XW Huang wrote:
>> Dear martin,
>>
>> Thanks for your reply!
>>
>> In my tests, the IPs hosted by the failed node was moved to other nodes
>> correctly.
>> But all records in test.tdb can not be fetched on all nodes, i.e. {node-0,
>> node-1, node-2, node-3}.
>> It seems hanging when doing ctdb_fetch_lock:force_migration
>> when node-0, node-2, node-3 tries to fetch the record from test.tdb.
>> Is there any mechanism to revoke __transaction_lock__?
>>
>> Thanks again. I really appreciate receiving any input from smart people
>> like you guys.
>>
>> az
>>
>> 2012/11/16 Martin Schwenke <martin at meltin.net>
>>
>>> On Sun, 11 Nov 2012 15:23:02 +0800, XW Huang <xwhuang123 at gmail.com>
>>> wrote:
>>>
>>>> A record (/tmp/test) is stored in a persistent tdb (test.tdb) by this
>>>> command.
>>>>
>>>> $sudo ctdb pstore test.tdb /tmp/test /tmp/test
>>>>
>>>> This record is fetched again and again on node-1.
>>>> Then, node-1's network interface was turned down to simulate it is
>>> crashed
>>>> by this command.
>>>>
>>>> $sudo ifconfig eth0 down
>>>> [...]
>>>
>>>> [...]
>>>> However, the records in test.tdb can not be fetched anymore.
>>>> But "ctdb getdbstatus" says test.tdb is healthy
>>>> and "ctdb catdb" can dump its content:
>>>> [...]
>>>
>>> It sounds like you are still trying to fetch the record on node 1.
>>> That won't work.  CTDB isn't available on that node.
>>>
>>> If you are providing a CIFS service using Samba/CTDB then when a node
>>> fails, the IPs hosted by the failed node will be moved to other nodes
>>> so that they can continue to provide the CIFS service. Then any data
>>> that Samba needs from CTDB can be fetched on those other nodes.
>>>
>>> Does that help?  :-)
>>>
>>> peace & happiness,
>>> martin
>>>
>
> --
> "Implementing CIFS - the Common Internet FileSystem" ISBN: 013047116X
> Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
> jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
> ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
> OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org